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I
VAN NO-STRAND'S
ECLECTIC
MAlii
VOLUME V.
JTJLY-DECEMBEB,
1871.
NEW YORK: D . VAN NOSTEAND, PUBLISHER
23 Murray Stkket and 27 Wabeen Steeet (up staies).
1872.
I
4$
CONTENTS.
■V^OI-.. 'V-
Page
Abutments, Iron 34
Accidents on Indian Railways. 102
To Railway Structures... 251
Action of water on iron 548
Aerial flight 530
Alloy, Useful Ill
Alloys of iron and manganese . 95
Alsace, public works of 289
Amber 559
American fire-arms in Europe . 105 Institute of Mining Engi- neers 335
American pig 659
Railways, increasing loads
on Ill
Railway statistics 441
Street cars abroad 551
Telescopes 222
Views of patent laws 658
Ammoniacal gas as a motive
power 290
Ancient time-keepers 491
Animal mechanics 174
Apparatus, aeronautic 7
Bischofs 36
Application of steam to canals. 84
Appointment, naval 443
Architecture, pointed, dome in 522
Starting point for 57
Style in 428
Arkansas as an iron producer. . 326
Artillery, mode of discharging. 556
Astronomical observation 14
Atchinson bridge. 332
Aurora, spectrum of 50
B illoon compass 305
Belgian iron trade 312
Bessemer steel works 438
Big gun of Woolwich 99
Bischofs apparatus 36
Blast furnaces in the German
furnaces 438
At South St. Louis 98
Blasting timber wih dynamite 666
Boiler company, Weston 16
Deposits 112
Explosions 344,347, 390
Explosions, steam 469
Inspection 380
Boilers, light 45
Bonetta gunboat 105
Book Notices : *
Anstruther, P. Theory of
gunnery '.108, 334
Armour, J. Power in mo- tion ;. 334
Bridges, T. W. Gunner's
pocket-book 334, 446
Burgh, N. B. Condensa- tion of steam 445
Burt. Key to the solar compass and surveyor's
companion 222
Cooke, M. C. Hand-book
of British Fungi. 557
Davidson. M'»del drawing 444 Deschanel, A P. Elemen- tary treatise on natural
philosophy 557
Diedrichs, J. H. Theory
of strains 557
Donaldson, W. Switches
and crossings 445
Page Book Notices :
Fishbourne, G. E. Current fallacies on naval archi- tecture 108
Fyfe, J H. Triumphs of invention and discovery in art and science 335
Gillespie, W. M. Manual of the principles and practice of road mak- ing 109
Gillett, R. H. Federal gov- ernment, its officers and their duties 333
Gillmore, L. A. Practical treatise on Coignet Beton 445
Greener, W. W. Modern breech-loaders 445
Grindy, C. C. Gas con- sumer's guide ; few words about gases 334
Hann, J. Rudimentary treatise on analytical ge- ometry 558
Harvey, S. Keport on the bridges across the Ohio river ; instructions for the management of Har- vey's sea torpedo 109
Heather, J. F. Mathemati- cal instruments 558
Huntington, W. S. Road- master's assistant and sectionmaster's guide. . . 333
Joynson, F. H. Metals used in construction .... 334
Laughton. Physical ge- ography in its relation to the prevailing winds and cuirents 222
Leeds, L. W. Treatise on ventilation 445
Maxton, J. Workman's manual of engineering drawings 557
Morgans, W. Manual of mining tools 557
Peirce, J. N. Logarithmic and trigonometric func- tions 664
Plattner. A manual of blowpipe analysis .... 663
Poor Manual of the rail- roads of the United States for 1871-72 222
Procor. Light science for leisure hours 222
Rice, E. C. Tables of cir- culating excavation and embankment . 109
Secchi, Padre. Le Soleil. . 664
Seymour, Silas. Narrow gauges 664
Smith, F. H. Gymnastic and technical education. 445
Spon's Dictionary of engi- neering 445
Spooner, E. C. Narrow gauge railways 663
Stuart; C. B. Military en- gineers of America 110
Tred^old, T. Elementary principles of carpentry. . 10S
Page Book Notices :
Tate, R. Physical geology 557 Tyndall, J. Fragments of science for unscientific
people 108
Wood, Prof. Devolson. A treatise on the resistance
of materials 663
Borneo commerce 336
Brazilian railways 441
Telegraphs 444
Breech-loading ordnance of the
middle ages 556
Bridge building, military 435
Construction 254
Council Bluffs 554
East River 381
International 444
Keokuk and Hamilton 374
Poughkeepsie suspension. . 554
Rock Island..... 332
St. Charles 178
Bright colors, production of. . . 335
Brighton railway 509
British iron-clads, building 555
Naval bull-dog 554
Broken cable of the Shetlands. 67
Building arts of Russia 410
Bull-dog, British naval 554
Burnt iron and burnt steel 51
Cable, Chinese 64, 112
Caissons, Ransome's stone for. . 434
Stone 408
Calcutta, cost of drainage works 210
California railways 16
Tea 538
Camel's hair 289
Canal between the North Sea
and the Baltic 554
Illinois and Michigan 330
Canals, Application of steam to 84
Of Canada 147
Steam on 220
Car coupling. 330
Shops of the Housatonic
railroad 329
Wheel, new 102
Carriages, railway 216
Cartridge cases, metallic 164
Henry's dummy 332
Casks, manufacture of 598
Casting gas and water pipes,
new process of. 665
Castings, large 592
Cast iron, durability of 316
Railroads ." 551
Cathedral of Cologne 486
Cause of low barometer in the polar regions and in the cen- tral part of cyclones 525
Cement, Chinese 112
Notes on 204
Ceylon, railways in 489
Chains, hoop iron 101
Channel service, improvement of 37
Tunnel 574
Chassepot 380
ChatwoodandCrompton's steam
trap 5
Chicago river 332
China, mineral resources of 65
Chinese and Japanese art 539
Chinese cable 64, 112
CONTENTS.
Page
Chinese cement 112
Circulation of strains in trasses •'*•'*
Cleveland iron works 326
Clocks and chronographs 228
Coal cutting; improvements in. 627
Fields, English, duration of 492
Fields ofthe world 495
In Nizam 560
In the Rocky Mountains.. •!!']
Coasting steamers, iron 218
Coining of gold 893
Cold galvanization of iron 54
Cologne, cathedral of 486
Column, Place Vendome . . . 156 Commercial economy of mer- chant steamers 52
Computation of effects of gradi- ents '..... 126
Compressed gun-cotton l'-H
Concrete '275
Condensation in steam cylinders 198 Condition of carbon and silicon
in iron and steel 70
Construction of traction engines 631 Copper mines of Lake Superior 518 Cost of track material in Ne- braska GG1
Cost of drainage works of Cal- cutta 210
Of the siege of Paris 175
Of making Missouri iron. . 438
Council Blutl's bridge 554
Critical examination of theideas
of inertia and gravitation. 496, 605
Cumberland ore 493
Curious calculation concerning the war indemnity to be paid
to Prussia by France 224
Curves upon railways 399
Darien survey 219
Dome in pointed arcitecture. . . 522
Dynamite, nitro-glycerine.. . . 172
Deep water 369
Denver aud Rio Grande narrow
gauge 552
Detroit tunnel 107, 444
Delivery of water under great
pressures on the 544
Devastation 443
Dictionaries, technical 5 2
Direct Indus Valley railway.. . 215
Discharge gauge, automatic. 543
Disinfectants 510
Distribution of temperature in
the Norih Atlantic 362
Durability and deterioration of
iron 101
Durability of cast and wrought
iron 316
Duration of the English coal
fields 492
Dutch industry 258
Day Dream, launch of 218
Earth a magnet 229
Internal temperature of. . . 627
East River Bridge 381
Earthquakes, usefulness of 121
Earthwork tables 221, 594
Economy, locomotive 483
Elasticity and tensile strength
of wrought iron 82
Electricity, practical 432
Electric railwajr signals 215
Spark, experiments with. . 300
Electro-magnetic engines 142
Elementary aeronautic appara- tus 7
Elevated railway 300
Embankment, Thames 368
Engineering matters in Turkey 161
Page
Engineering schools in Italy. . . 6i;."i
Work in New ¥ork harbor. 552
Englues, King's valveless. ... 219
England!, iron trade in 100
English railway traffic 69
Tramway 536
Euphrates valley 859
Valley railway scheme. . . . 328 European and North American
railway 661
Europe, tire-arms in 105
Examples of the performance of
the electro-magnetic engines 142
Expansion of steam . 128
Expedition, aerial, Mr.Jansen's 532 Experiments at Snoeburynessl03,506
Willi the electro-spark 300
Experiment with water 312
Exploration on the Tiber 514
Explosions 469
Boiler 347, 390
Explosive compounds — espe- cially- dynamite nitro-glycer- ine.. ..... 172
Explosives, transport of 261
Fallacies, mechanical 616
Of seasoning lumber 336
Fastest time in the world 217
Fibrous iron, fusion of. 43
Finishing sleel Gbti
Flight, aerial 530
Flight, recent researches on . . 654
Flying machine 335
Forge lamp for laboratories. . . . Ill
French soldier's kit 104
Furnace, patent heating 438
Puddling and heating 549
Siemens' regenerative 48
Furnaces, blast 438
Fusion of wrought or fibrous
iron in reverberator}' furnaces 43
Galvanic battery, some forms of 189
Gas fountain at Delf 358
Furnace, heat restoring. . . 341
Gauges, railway 618
Gautreau'a dynametrical gov- ernor 537
General oceanic circulation 211
German naval invention 556
Navy 443
Torpedoes 333
Trade 175
Giant chimney 662
Girders, strength of, tested by
models 654
Gold, coining of 393
Governors, dynametrical, Gau-
treau's 537
Gradients, computation of ef- fects of 126
Graphite, origin of 27
Gravitation, examination of... 496
Examination of the ideas
of 605
Great bridge at St. Charles 105
Britain, iron trade of 325
New York city railway de- pot ... . 220
Railroad lease 102
S teel rail mill in Bethle- hem (Pa.) 331
Sun spot of 1843 315
Greenock harbor 443
Gunboat, Bouetta 105
Gunpowder 333
Guns vs. targets t 501
Half-and-half stylea of modern
architecture 370
Hannibal bridge 306
Harbor, Greenock 443 '
Pa ire
Harbors, Indian 443
Harvey torpedo 555
Heat restoring gas furnace 341
Solar 8, 269
Hematite ore and iron of Cum- berland 493
Ore of Cumberland 463
Henry's dummy cartridge 332
Historical sketch of the canals
of Canada 147
History of military breech- loaders 560
Holmes' storm and danger sig- nal light 105
Hoop iron chains 101
Hoosae tunnel 554
Horse power of steam engines. 128
Housatonic railroad, car shops of 329
Hydraulic train lifts 80
Icel ierg alarm 468
Illinois and Michigan canal... . 330 Central railway locomo- tive report for March 329
Waters of. 336
Impermeable street surfaces, ad- vantages of 586
Importance of modern kart in- dustry 539
Improvement of the Channel service between Folkestone
and Boulogne 37
Improvements in coal cutting. 527 Increasing loads on American
railways Ill
Indian harbors 443
Ship canal 106
India-rubber vs. iron tires 402
Industries of Foreign countries. 234
Industry, Dutch 258
Inertia, examination of ' 496
Examination of the ideas of 605 Influence of certain metals on
the quality of steel 503
Institution of civil engineers. . 224
International bridge 444
Invention of the steam hammer 331
Iron abutments 34
Alloy of 536
And manganese, alloys of. 95
And steel ' 609
And steel industries in for- eign countries 234
And steel, progress of 133
At low temperatures 325
Burnt 51
Carbon and silicon in 70
Character of 100
Clads, British., 555
Clads in Turkey 104
Coasting steamers 218
Durability, deterioration of 101
Galvanization of 54
Making in Wisconsin 658
Manufacture, Scotch 437
Of Cumberland 493
Paper 213
Phosphorus in 437
Pig, prices of since 1860. . 659
Screw steamer. 104
Slag for street pavements. Ill
Telegraph posts 54
Trade in England 100
Trade, German 175
Trade of Great Britain and on the continent of Eu- rope 325
Tubes, strength of 481
Italian mercantile marine 103
Janssen's aerial expedition. . . . 532
Japanese art 539
CONTENTS.
Page
Japanese Printing 69
Students in the United
States 127
Japan, surveying instruments
for....* 200
Telegraph to 54
Kansas, marble in 112
Keokuk and Hamilton bridge. 374
King's valveless engine 249
Laboratories, forge lamps for..' Ill Lake Superior and the copper
mines 518
Large-planing mill 560
Largest rope in the world 98
Laws for navigation of the
Thames 315
Launch of the steam yacht Day
Dream 218
Launching of ships 25
Life of American ships 144
Light boilers 45
Lighthouse, Sha-wei-shan .... 552
Lime, notes on 204
Line to the Pacific 102
Liquid and gaseous state of
matter 344
Lithofracteur 18
Locomotive, double bogie 661
Locomotive economy 483
Report -. 329
Narrow gauge 442
Locomotive, old 660
Lorraine, public works of . 289 Low barometer, cause of, in the
polar regions 525
Machine, puddling 547
Mackie's steam perforator 6-i4
Madras telegraph line 64
Making and repairing of roads. 28
Manufacture of casks 508
Manufacture of steel 95
Of Russian sheet iron 361
Manufactures, porcelain 521
Marble in Kansas 112
Trade of the Apuan Alps. . 223 Matter, gaseous and liquid states
of. 344
Mechanical fallacies 616
Tests 201
Mechanics, animal 174
Mercantile marine, Italian 103
Metallic cartridge cases 164
Meteorology of the spring
months 110
Metric system 163, 449, 661
Microscopic character of iron
and steel 100
Mine ventilation, system of. . 301
Mineral resources of China. ... 65
Wealth lost to France 31
Mining engineers, institute of, . 335
in Japan 559
Milan, steam engines at 210
Military railway and bridge
building 435
Milk, preservation of 617
Missouri iron, cost of making. . 438
Mitrailleuse 555
Mode of discharging artillery. . 556
Modern architectnre 370
Monitor turret ships for coast
defence 613
Monster observatory 222
Mont Cenis, railway over 550
Tunnel 113, 225, 337, 465
Monuments, public 356
Mortar, notes on 204
Selenitic 278
M. Janssen's balloon compass . 305
Nails, wjoden 110
P;,ge
Narrow gauge 562
Gauge locomotives 442
Gauge roads 216
Gauge railways 349
Gauge railroads 406
Natural history of paving stones 280
Naval appointment- 443
Naval armaments, German .... 663
Invention, German 556
Navigable water 16
Waters of Illinois 336
Navy 443
Of England 555
German 4t3
Nesquehoning tunnel 107, 650
New alloy of zinc and iron 536
Atlantic steamer 24
Car wheel 102
Mitrailleuse 555
Ohio and Mississippi 327
Pier system of New York . . 106 Puddling and heating fur- nace 549
Star chart 480
Steamers 67
Storm and danger signal
light 203
Test paper 416
New Jersey steel and iron com- pany 658
New petroleum car 661
New York harbor, engineering
work in 552
Pier system of 106
Railroads 330
Nickel plating 200
Nitro-glycerine test 367
Non-conducting steam cjdin-
ders 187
North American Pacific coast. . 256 North America, zinc production
of 177
Northern Pacific surveys 551
Notes, earthwork 17
On lime, mortar, and ce- ment 204
Novel surface condenser, 560
Observation, astronomical. .... 14
Oceanic circulation, general... 211
Old locomotive 660
Omnibuses in Paris 256
On an automatic discharge
gauge ... . . 543
On the architectural treatment
of Portland cement 166
Some forms of galvanic
batten' 189
The delivery of water un- der great pressures 544
« )rdnance, breech-loading 556
Ore, titanic 32
Origin of the graphite 27
Oxygen, preparation of. 401
Pacilic coast 256
Line to 102
Railway, traffic of 480
Painsville and Youngs town rail- way 552
Paper, iron 213
Paris, cost of the siege of 175
Patent heating furnace 438
Paving stones, history of 280
Peculiar boiler deposits 112
Pennsylvania railroad company 441
Performance of steam boilers.. 662
Petroleum car 661
Philadelphia, railways of 172
Phosphorus in iron and steel. . . 430
In steel 214
Picking tools 448
Page
Pins, production of 16
Place Vendome column 156
Restoration of 257
Plaster of Paris manufacture. . 423
Plating, nickel 200
Pneumatic tubes, transmission
through 509
Pollution of rivers 131
Porcelain manufactures 521
Portland cement, strength of. . 62 Portland cement, architectural
treatment of 166
Poughkeepsie suspension bridge 554
Practical electricity 432
Preparation of oxj'gen 401
Preservation of sheet iron ves- sels 262
Printing, Japanese 69
Problem in bridge construction 254
Process, Sherman 36
Production of bright colors on
metals 335
Production of pins 16
Progress of iron and steel in- dustries of foreign countries. 133 Proposed canal between the
North Sea and the Baltic 554
Proposed tunnel under the
Clyde 553
Public monuments 356
Public works of Alsace and
Lorraine 2»9
Puddling machine 547
Rail manufacture, s' eel 100
Railroading underground 551
Railroad company, Pennsylva- nia 441
Lease 102
Southern, Utah 400
Underground 443
Railroads, cast iron 551
Developing onr resources. . 101
Narrow gauge . . ..349, 406, 618
New York 330
Railway, Brighton 509
Across the Andes ... 662
Building, military 435
Carriages 216
Companies, responsibility
of. 420
Consolidation 661
Depot, New Yorfc 220
Elevated 300
European and North Ameri- can 661
Iron in Russia. 660
North Missouri 661
Utah Southern 662
Railway, Indus Valley 215
Iron in British America . . . 548
Over Mount Cenis 550
Painsville and Youngs- town 552
Rigi 313, 442
Scheme, Euphrates Valley. 328
Signals, electric 215
S ructures, accidents to. . . 251
Gauges 618
Development, English and
Foreign 577
Railways, Brazilian 441
California 16
Curves upon 399
Indian, accidents on 102
Ceylon 489
Iu time of war 216
In Turkey 216
Narrow gauge 349, 406, 618
Russian 196, 520
Ransome's stone for caissons. . . 434
CONTENTS.
Recent researches on flight 6o4
Bocording earthwork notes. ... 27 Bettering apparatus tor steam
MUges.." 448
Relative value of different
kinds of fuel 21
Gold and silver 448
Remedying the want of fuel in
private houses 223
Responsibility of railway com- panies 420
Restoration of the Place Yen- dome Column 257
Review of the telegraphic sit- uation 59
Rhvsimeter 521
Rigi railway 313, 442
River, Chicago 332
Rivers, pollution of 131
Road steamers in Brazil 868
Traction of 368
Roads, making and repairing
of 28
Narrow gauge 216
Rock Island bridge 332
Rock surveying, submarine. . 355
Rocky Mountains, coal in 491
Rolling of gunboats 665
Rope, largest in the world 98
Russia, building arts of 410
Russian railways 196, 520
Russia sheet iron, manufacture
of. 361
Sandwich Islands, telegraph to 54 Sanitary advantages of smooth and impermeable street sur- faces 586
Scale works at St. Johnsbvuy . . 213
Science in plain English . . . . 584
Scotch iron manufacture 437
Scotland, manufacturing indus- try of 55
Selection and use of stone 263
Selenitic mortar 278
Self-acting rudder 560
Sha-Wei-Shau lighthouse 552
Sheet iron stacks 659
Sheet iron, thin 405
Sheet iron vessels, preservation
of 262
Sherman process 36
Shetland, broken cable of 67
Shifting stuff 388
Ship canal, Indian 106
New Era 218
Building in Belfast 443
Ships, launching of 25
Life-boats 333
Life of 144
Shoeburvaess. experiments
at ...* 103, 253, 506
Siemens' regenerative furnace. 48
Slag cement 664
Slag, iron Ill
"" Utilization of 214
Small steam engine 480
Smooth street surfaces, advan- tages of 586
Solar heat 8
Solar heat, influence on the
earth's rotary velocity. . 269
Specific gravity of oils 446
Spectrum of the aurora 50
Spring months, meteorology of. 110
Submarine rock surveying.... 355
Sun spot of 1843 315
Surface movements of the earth 666
Survey, Darien 219
Surveys, Northern Pacific 551
Surveying instruments for
Japan 200
New 629
Page
St. Charles bridge K>5, 17*
St. Johnsbmy, scale works at, 218
Star chart, new 480
Stair df Arkansas as an imn
pit ilucer 326
Starting point for a modem
style of architecture 57
Statistics, American railway.. Ill
Steam '. . . 145
Cylinders, condensation in 198
Cylinders, non-conducting 1x7
Steam boiler experiments 662
Engines at Milan 210
Engines, horse power of. . . 128
Engines, small 480
Expansion of 128
Hammer, invention of 331
On common roads 425
On the canals 220
Steam perforator, Mackie's. . . 664 Trap, Chatwood and
Crompton's 5
Yacht, launch of. 218
Steamer, Iron Screw 104
Steamers, new 67
Steamer, New Atlantic 24
Steamers, road 360
Steel 395
As applied to ship-building 68
Burnt .-, 51
Carbon and silicon in. 70
Character of. .' 100
Steel, finishing 658
Influence of certain metals
on the quality of. 503
Manufacture of 95
Phosphorus in 214, 437
Rail manufacture 100
Stevens Institute of Techno- logy 324, 533, 581
Steel Works, Bessemer 438
Stone caissons 408
Cement 448
Selection and use of. 263
Storm and danger signal light,
Holmes' ' 105
Strains in trusses 479
Street cars, American 551
Locomotion 298
Railways in Melbourne. . . 373
Strength of iron tubes 481
Of girders tested by models 654
Street railways of Philadelphia 102
Strength of building material. . 447
Of Portland cement 62
Stuff, shifting 388
Style in architecture 428
Suez canal, influence of. 664
Sun, temperature of. 599
System, metric 163
S}rstem of mine ventilation 301
Tables, earthwork 594
For earthwork 221
Tank filter 224
Targets vs. guns 501
Tea in California 538
Technical dictionaries 512
Technology, Stevens Institute
of 324,533
Telegraph, Brazilian 444
Line, Madras 64
Posts, iron 54
To Sandwich Islands and
Japan 54
To the Western Hebrides. 24
Telegraphic situation, review of 59 Telegraph}', pneumatic tube
system 417
Telescopes on guns 112
Temperature in the North At- lantic 362
Of the sun 599
Page
Test paper 416
Tests, mechanical 2ol
Testing boilers 417
Thames embankment 368
The thirty-live ton gun 668
Thin sheet iron 405
Through die Euphrates Valley 359
Tiber, exploration on 514
Timbering of trenches and tun- nels applicable to railway and
sewerage works 376
Time, fastest in the world 217
Timekeepers, ancient ». . 491
Titanic ore 32
Torpedo, Harvey 555
Torpedoes, German 333
Turkish 443
Working 467
Track material, cost of in Ne- braska 061
Traction wheels, bite of 192
Of road steamers 368
Engines, construction of. . . 631
Tramways 400
English 5.16
Trans-continental trip 438
Transmission of power by wire
ropes 421
Through pneumatic tubes. 509
Transport of explosives 261
Traffic, English railway 69
Of the ^Pacific railway .... 480
Trenches, timbering of 376
Trip, trans- con tinental 4£8
Trusses, strains in 33, 479
Tube system, pneumatic 417
Tunnel, Channel 574
Detroit 107, 444
Hoosac 554
Mount Cenis. .113, 225, 337. 465
Nesqnehoning 107, 650
Tunnels, timbering of 376
Under the Clyde 553
Turbine fluid meter 401
Turkey, engineering matters., lt-1
Iron-clads in ) 04
Railways in 216
Turkish torpedoes 443
Turret ships 613
Underground railroad 443
Railroading 551
Temperature 447
Useful alloy Ill
Usefulness of earthquakes 121
Utah southern railroad 400
Utilization of slag 214
Of waste material in mining 560
Utilizing sewage, novel mode of 665
Washing of canal banks 665
Water, action of, on iron 548
Experiment with 312
Navigable 16
Wealth, mineral, lost to
France 81
Western Hebrides, telegraph to. 24
Wet steam 145
Weston Boiler Company.. . 16
What is steel 395
Wire rope manufacture 658
Wire ropes 421
Wood made incombustible.... 112
Wooden nails 110
Woolwich, big gun of. 99
Working torpedoes 467
Wrought iron, durability of. . . 316 Elasticity and tensile
strength of 82
Fusion of 43
Zinc, alloy of 536
Production of North Ameri- ca 177
d^t* ./vUtCC
VAN NO ST RAND'S
ECLECTIC
ENGINEERING MAGAZINE.
NO. XXXI.-JULY, 1871 -VOL. Y.
BIOGEAPHICAL SKETCH OF BENJAMIN H. LATROBE.
Benjamin H. Latrobe was born on the 19th of December, 1806, in the city of Philadelphia. He was the fifth child and youngest son of Benjamin H. Latrobe, well known as an eminent civil engineer and architect, in the early part of the present century, and especially in connec- tion with the Capitol of the United States, the best features of which were designed and executed by him, although he did not live to complete the building. Mr. Latrobe, senior, was descended from a French Protestant family, which had emigrated to Ireland. His father was an English clergyman, but his mother was a Pennsylvania lady of the Antes family, well known in Montgomery county of that State. He emigrated to America in 1798, and being a widower, married, in 1800, the eldest daughter of Isaac Hazle- hurst, a Philadelphia merchant, and also an Englishman by birth.
The subject of the present memoir was not educated for the profession he after- wards pursued, and to which he might have been so well trained in his father's office. He was intended for the law; and, although his father died when his son was but 14, his purpose in regard to him was adhered to, and having graduated at the Roman Catholic College of St. Mary's, in Baltimore, at the age of 17, he entered a law office, as a student, and was admit- ted to the Baltimore bar before he had completed his twentieth year. He went Vol. V.— No. 1.— I
soon after to New Jersey, and commenced the practice of law in Salem county ; but the climate not agreeing with his health, he returned to Baltimore in 1829. Having meanwhile discovered that the legal pro- fession was not to his taste, he left it the following year and entered the service of the Baltimore and Ohio Railroad Com- pany, as an assistant of Jonathan Knight, then Chief Engineer of that Company.
The brother of the subject of our sketch, J. H. B. Latrobe, Esq., the dis- tinguished legal counsellor of the Balti- more and Ohio Railroad Company, was educated as an engineer ; but maturity brought to him a taste for metaphysics and law, and they have each chosen the path for which nature intended them, and are leading men in their respective professions.
Benjamin H. Latrobe, being already an accomplished draughtsman, and a fine mathematician, soon rose through several subordinate positions, to the rank of principal assistant to Mr. Knight, and in 1832, began the location of the Washing- ton Branch Railroad, under his direc- tions. This service occupied him until the close of 1833. In the following year, he located that portion of the Baltimore and Ohio Railroad, between the Point of Rocks and Harper's Ferry, which had not been previously established by Mr. Knight, conjointly with the Engineer of the Chesa- peake and Ohio Canal Company.
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In the same year he reconnoitred and reported upon a railroad route from Har- per's Ferry to Chambersburg, through Hagerstown, Maryland.
In 1835, Mr. Latrobe was appointed Chief Engineer of the Baltimore and Port Deposit Railroad, which was located and built under his direction from Balti- more to Havre-de-Grace, 31 miles. The features which distinguished this road were, 3 bridges of considerable length, 2 of them with draws, over rivers of mode- rate depth of water, but almost unfathom- able mud. They were supported upon piles, and were the first long railroad bridges of this description erected in the United States. The ferry at Havre-de- Grace was also peculiar, the cars, with freight and baggage, being transported across the river, | of a mile wide, upon tracks laid upon the upper deck of a steamboat, so as to avoid breaking bulk ; a plan since adopted successfully upon other railroads in this countiy. Mr. La- trobe left the service of the Baltimore and Ohio Railroad, when he entered the other, in 1835, but was recalled in 1836, and ap- pointed " Engineer of Location and Con- struction," by that Company.
In this capacity, he executed all the surveys, planned and superintended all the works of construction, with the ad- vice of Jonathan Knight, the Chief Engi- neer. He remained in the service of the Baltimore and Port Deposit Railroad Company until the opening of that work in July, 1837, and thenceforward devoted his exclusive attention to the Baltimore and Ohio Railroad surveys, which were prosecuted during that year to Wheeling and Pittsburg, on the Ohio. In 183S Mr. Latrobe made an elaborate report upon these surveys, which extended over a section of a mountainous country upwards of 300 miles in length and 50 or 60 miles in breadth, in a manner to give much professional credit to himself. It was through this able report that Mr. Latrobe became well known to the profession throughout the country, and he gained soon after a high reputation by a report upon the principal railroads of the East- ern and Middle States, in which he was associated with Mr. Knight.
In this year, also, the four inclined planes over Parr's Ridge were replaced by a railroad, with grades of 80 ft. per mile, as located by Mr. Latrobe and con-
structed under his supervision, and the general direction of the Chief Engineer. Some important changes were also made in the bed of the road, by which a part of its most objectionable curves were dis- pensed with.
In 1839 the Baltimore and Ohio Rail- road from Harper's Ferry to Cumber- land, 98 miles, was finally located, and its construction, upon the plans prepared by Mr. Latrobe and approved by Mr. Knight, commenced. The work of chief interest upon that part of the road were 3 tunnels — the longest 1,200 ft. — and several bridges of considerable magnitude built of timber, upon a plan approved by Mr. Latrobe, and in which arch braces were adopted, with counterbraces and tie-rods between them. The plan of these structures is fully described in Haupt's work on bridges.
This important division of the road was open for travel in November, 1812, Mr. Latrobe having previously been appointed Chief Engineer, upon the retirement of Jonathan Knight in April *of that year.
After the completion of the road to Cumberland, Mr. Latrobe was occupied during the succeeding years, up to 1817, in a variety of duties, all of which, how- ever, related to the extension of the rail- road beyond Cumberland to the Ohio river. He reconnoitred the country through Virginia, in 1813 and 1811, and in the latter year pursued his examina- tions into Ohio, to the leading centres of trade of that State. He also visited Rich- mond during each winter of these years, in aid of the efforts the Company were making to obtain an acceptable right of way through Virginia, and was deputed by President McLean, then on the eve of his departure as Minister to England, to make the annual report to the stockhold- ers, in July, 1815, and on his recommen- dation they rejected the Virginia law of that year.
The transportation department of the railroad from Baltimore to Cumberland, was also under his general direction dur- ing that time, and in 1816 the old plate rail track was replaced by T rail, and many additional changes were made in the road bed, and its most objectionable curves.
In 1817 the surveys west of Cumber- land were resumed, and in that and the two succeeding years, the line to Wheel-
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ing, 200 miles in length, was located, and most of it placed under contract. In the location, plans, and construction of this part of the Baltimore and Ohio Railroad, Mr. Latrobe performed a most difficult task. The country presented unusually bold features, even for a mountainous re- gion. Two main summits, one of 2,600, and one of 2,000 ft. above tide water, had to be passed, with a valley between them less than 1,400 feet above the ocean. Lines of better grade might have been had, but with shorter curves and a greater expenditure of distance and cost of con- struction. Mr. Latrobe selected the most direct, and easiest to build, although it involved an inclination unprecedented in leading railroad routes.
The principal summit of 2,600 ft. above tide water, between the Potomac and Youghiogheny, was passed by a grade averaging 116 ft. to the mile, for 15 con- tinuous miles. The same grade was used for 8| miles in descending to the valley of Cheat river; and in crossing the second summit of 2,000 ft., between this river and Tygart's Valley, about 6 miles of 105 ft. grade was used on either side.
Mr. Latrobe had adopted this location on his own responsibility, as the Com- pany's Chief Engineer; but as it presented novel and important questions, a consult- ing boai'd, composed of Jonathan Knight, Capt. John Childe, and himself, was ap- pointed to consider the subject. Under the direction of this board, new surveys were made in 1848, which resulted, how- ever, in showing that the best ground had already been selected; and in an elabo- rate report, made soon after, the location of Mr. Latrobe was approved by his col- leagues, and finally adopted by the Com- pany.
The road was accordingly constructed upon that line, and its natural features, and the works connected with them, have become well known throughout the coun- try. Upon the 200 miles between Cum- berland and Wheeling, there are 12 tunnels of various lengths, — the longest, the "Kingwood," 4,100 ft. — through a compact slate rock, overlaid in part by a good limestone roof, and for the rest of its length supported by brick arching. There is a long deep cut at each end of the tunnel. It was worked from both ends, and from 3 shafts 15 by 20 ft. sq., and 180 ft. deep. The greatest height of
the riclge over the tunnel is 220 ft. The time employed on the work was about 2 years and 8 months, and the number of cubic yards removed in the tunnel, was about 90,000, together with about 110,000 yards of earth and rock outside, for the approaches.*
The next most important work was the "Doe G-ully" tunnel, 1,200 ft. in length, where a bend in the Potomac river is crossed, and a distance of nearly 4 miles saved. The approaches to this work are imposing ; for several miles on each side of the tunnel, the road occupies a high level on the steep hill sides, affording an extensive view of grand mountain scenery. The tunnel is through a com- pact slate rock, which is arched with brick to preserve it from future disintegration by atmospheric action. The fronts or facades of the arch, are of fine white sand- stone, procured from the summit of the neighboring mountain. The height of the hill above the tunnel, is 110 ft. The excavations and embankments adjacent, are very. heavy, through slate rock. The bridges are also numerous, and the " tres- tling," across the gorges, on the ascent of the Cheat River Hill, are structures of novel character, being viaducts supported by slender pillars of cast iron, very light in appearauce, yet strong and durable. One of these viaducts is 46, and the other 58 ft. high ; the former resting on a solid wall of masonry, whose foundation is 120 ft. below the base of the columns ; the latter on a similar wall, with foundations 74 ft. below base of columns. The pillars lean inwards to give stability, and are thoroughly tied and braced, and carry 2 tracks of rails at the grade of the road.
In the design and erection of the bridges and viaducts, Mr. Latrobe was assisted by Albert Fink, a talented Ger- man engineer, who was associated with Mr. Latrobe as an assistant for several years, and is now earning a high reputa- tion as an engineer and bridge architect, in the South-West.
The cost of the Baltimore and Ohio Railroad from Baltimore to Wheeling, 379 miles, completed June 1, 1853, was
* At the crossing of tbe mountain over this tunnel, previ- ous to its completion in 1853, the grade was upwards of 500 ft. per mile, over which a locomotive engine propelled a single car at a time, weighing, with its load, 13 tons, at a speed of upwards of 10 miles per hour. When the track was wet or frosty, the engine and its load occasionally slipped backwards, and often ran with locked wheels, down to the' bottom of the grade w.thout injury.
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$15,629,000, including nearly $1,000,000 for reconstruction east of Cumberland, after the road was opened to that point in November, 1842.
The working of the Baltimore and Ohio Railroad, between Cumberland and Wheeling, has abundantly manifested the judiciousness of its location and manner of construction. The high grades have been operated with great economy and entire safety, by means of a class of loco- motives, using the extremely cheap mineral fuel which abounds in that region. In addition to the work already described, and upon which Mr. Latrobe has been engaged as Chief Engineer, he acted, from 1850 to '54, as Consulting Engineer of the Cincinnati, Hillsboro and Parkersburg Railroad, and in 1855, the Fredericksburgh and Gordonsville Rail- road Company employed him in the same capacity.
In 1854 he visited South Carolina to examine the location of the Blue Ridge Railroad of that State, upon which he made an able report of some length, which was published by that Company. He again visited the road in 1857 to give his professional testimony upon questions connected with the object of his previous visit.
In 1851 Mr. Latrobe was appointed Chief Engineer of the North- Western and Yirgina Railroad Company, extend- ing from Grafton, a point on the Balti- more and Ohio Railroad, to Parkersburg on the Ohio river, 92 miles below Wheel- ing. In the contest for the right of way through Virgina for the Baltimore and Ohio Railroad, Mr. Latrobe always favor- ed the most direct line to Cincinnati, and opposed the Wheeling terminus. He, therefore, entered con amove into the con- struction of the Parkersburg Railroad, under the charter which the citizens of that place had succeeded in obtaining.
The country between Grafton and Parkersburg was very much broken, and required patient examination to secure the best line, which was only obtained by a free resort to tunnelling through the numerous high and sharp ridges dividing the many watercourses. No less than 23 tunnels, in 104 miles, had to be driven, the longest 2,700 ft. These tun- nels are the most striking features of the road. There are many bridges, but none of great magnitude, and several embank-
ments, but none of extraordinary altitude or length. The depot arrangements upon the Ohio river at Parkersburg are worthy of attention, for their excellent facilities for handling freight by means of ma- chinery used for raising and lowering it from steamboats.
In 1856, Mr. Latrobe was appointed President of the Pittsburg and Connells- ville Railroad Company, and also of the Northern Virginia Railroad Company. From this last position he retired in the latter part of 1857, and devoted his whole attention to the direction of the Pittsburg and Conn ells ville Rail- road, performing, from early in 1858, the duties of Chief Engineer of the same Company. In 1864 he retired from the Presidency of this Company, retaining, however, the Chief Engineership, which he still holds.
In 1863 he became Consulting Engineer of the Philadelphia, Wilmington and Baltimore Railroad Company, in connec- tion with the bridge then about to be built across the Susquehanna river at Havre-de-Grace. In 1865, he was ap- pointed Consulting Engineer of the Mis- souri Railroad Company, more especially in reference to the bridge about being erected over the Missouri river at St. Charles, which position he held for about two years.
In 1866 he was appointed Consulting Engineer to the Governor and Council of Massachusetts, in connection with the Troy and Greenfield Railroad, and Hoosac Tunnel, and held the office until January, 1869, when he resigned.
Early in 1869, on the invitation of the late John A. Roebling, he became one of a Consulting Board of Engineers upon the plans of the " East River Suspension Bridge," and continued to act with the Board until its services were terminated, and report made in the autumn of the same year.
Such is a brief summary of 40 years of the professional life of this distinguished Civil Engineer. In looking through the numerous reports from his able pen, the author is at a loss to select from among them such as might be considered most worthy of notice and deserving of pre- servation as part of the professional his- tory of his time.
In 1846, when the Baltimore and Ohio Railroad Company was hesitating whether
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it would extend its road west of Cumber- land to Pittsburg through Pennsylvania, or to some Point below on the Ohio, in Virginia, the Pittsburg and Connellsville Kailroad Company, having located a part of its road, offered its charter to the Baltimore and Ohio Railroad Company (to whom Pennsylvania had refused to renew its former right of way on terms that would be accepted).
The Company decided, however, to go through Virginia rather than through Pennsylvania, even if they were compelled to make their terminus on the Ohio as far down as Wheeling. This decision was an unfortunate one for the Company ; for if the road had been first made to Pitts- burg, the State of Virginia would have finally accorded the right to Parkersburg (as has since been proved), and the 100 miles to Wheeling would have been saved, and could well have been spared, for in the final arrangement it has become mainly a local road.
Mr. Latrobe is now engaged in endeav- oring to accomplish that which he desired to have seen effected at first, and should he be so favored, may live to fill up the measure of his professional ambition — the completion, under his direction, of two great lines of railroad which are equally necessary to Baltimore.
He has been invited to take charge of other lines of railroad, but the interest he has always felt in the city of Baltimore, and the completion of her connections with the West, has always led him to de- cline engagements incompatible with that paramount object of his career as a Civil Engineer.
Mr. Latrobe is as distinguished for his modesty, urbanity, and gentlemanly d&> portinent, as for his eminence as an engi- neer. When complimented on the opening of the Baltimore and Ohio Railroad, at the Fairmount banquet, he characteristically replied, in part as follows:
" The merit which has caused my name to be mentioned in this connection, would doubtless have been exhibited to the same extent by any other professional man, who had the Fame opportunity of constructing a similar road over such a country. The general maps indicated the courses of the streams that were to facilitate the work; but where the mountains were to be crossed and tunnelled, and the rivers to be spanned, was a matter of careful exam- ination, in which I was aided by the talent and perseverance of skilful assist- ants, whose valuable services I shall always take pleasure in acknowledging."
In another place he says : " In crossing or tunnelling the mountains, and span- ning the rivers, sometimes one plan had to be adopted and sometimes another, and I have been constantly surrounded by able and accomplished assistants, to whom I take pleasure in according their share of whatever merit there may be found in the task I have accomplished."
A less sanguine temperament than that possessed by Mr. Latrobe would have recoiled from the task he saw before him, but its very difficulties seemed to give the work new attractions.
These works, from the Chesapeake to the Ohio, are a noble monument to his professional skill and indomitable per- severance. "
CHATWOOD AND CEOMPTON'S STEAM TRAP.
From 'c Engineering.1
We subjoin an engraving of a form of self-acting escape valve for drawing off water from steam pipes, etc., which has been designed and patented by Mr. Samuel Chatwood and Mr. James Crompton, of Bolton. The apparatus consists of a short vertical pipe open at the top, which should be at a lower level than the cylinder or other steam vessel to be drained. Around the upper part of the pipe is formed a valve face, the face being downwards. The upper part of the pipe with the valve
face above-mentioned is enclosed within a srnall vessel closed at the top, and having at its lower end a neck, which fits on a parallel part of the pipe below the valve face, and carries a corresponding valve seating set with its face upwards, so that when the vessel is lifted up the valve and seating are in close and steam-tight con- tact; and when the vessel drops, the seat- ings separate and allow any fluid con- tained in the vessel to escape through grooves or openings left in the neck.
6
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The action of this apparatus is as fol- lows: When steam only is in the pipes the vessel is pressed upwards owing to the internal area of the vessel being greater at the top than at the bottom by the amount of the area of the valve face, and thereby the valve and face are closed together so as to prevent the escape of steam. "When water is formed in the pipe by the condensation of the steam, it gradually accumulates in the closed ves- sel, until by its weight it overcomes the upward pressure of the steam, and causes the vessel to drop, thereby opening the
valve and allowing the water to flow out through the openings in the neck un- til the weight of the vessel and its con- tents falls below the upward pressure of the steam, which then lifts the vessel upwards again, thereby closing the valve and preventing the escape of any steam. There is placed above the mouth of the vertical pipe above-mentioned a guard, against which, when the valve opens, the condensed fluids are driven by the pres- sure in the steam vessel, so that by their downward reaction they tend to keep the vessel down and the valve open until the
vessel is empty or nearly so. The de- signers also apply a weighted lever to the closed vessel, by which the valve may be weighted more or less by moving the weight along the lever so as to regulate it to suit the pressure of steam in the en- gine or other steam vessel to which the apparatus is applied. The same end may also be effected by applying weights di- rectly to the valve without the interven- tion of a lever, or spring might be em- ployed in place of a weight.
The annexed figure shows one arrange- ment of the apparatus above described. In this figure, a is the short vertical pipe
having the valve face, b, at its upper part; c is the vessel closed at the top, and having at its lower part the neck, d, which carries the valve seating, e, corresponding to the valve face, b; f,f, are the grooves through which the condensed liquid is to escape; g is the guard carried above the upper end of the vertical pipe, a. The steam enters at k, and the condensed liquid is conducted off through the out- let /. The shape of the casting forming the lower part of the apparatus may be considerably varied. The weighted lever shown at Fig. 1 for drawing downwards the vessel, c, is marked h.
VAN NOSTRAND'S ENGINEERING MAGAZINE.
AN ELEMENTARY AERONAUTIC APPARATUS.
Translated from " Les Mondes.
M. Foselli, during the progress of the siege, has being very seriously studying the problem of navigable aeronautic ap- paratus. We shall not presume to say that he has solved the problem, but his attempt certainly presents some new and ingenious peculiarities. His aerostat is a simple cylinder terminated by a cone intended to cleave the air, and surmounted by cones called compensateurs, which, by means of a very simple apparatus, may be made salient or re-entrant, so as to equili- brate all the variations in pressure of the gas ; so that it is not necessary to throw out ballast, or to let off gas, in order to rise or descend. The cylinder is firmly fixed to a metallic chamber or cylinder with inflexible walls, of the same length as the machine. The chamber carries at its extremities propellers or helices which are intended to drive and guide the vessel. It is divided into compartments, each having its special use. One is hermeti- cally sealed and is to hold atmosphere to be breathed when at a very great height. M. Foselli does not think it possible to steer in the disturbed atmosphere of the region of snows; but intends to reach that great elevation in which there is absolute calm. He estimates that in the region of perpetual calms atmospheric tension is reduced to one-hrlf of what it is at the surface of the earth. Hence it was neces- sary to assure himself by rigorous calcula- tions that it would be possible at so great an elevation to introduce sufficient air into the living chamber to maintain an atmos- pheric pressure of 750 millim., which is necessary for the normal action of the essential organs of life. M. Foselli was much surprised at finding that the arm of a single man acting upon a small air-pump will maintain, at ordinary tension, an amount of air sufficient for the respiration of several hundred persons.
In a very rarefied and calm atmosphere a very slight motive force, or a very small screw, is sufficient to make the machine move, even when loaded. The experi- ments leave nothing to desire; the results are decisive.
A difficult problem remains for solution; that of the orientation of the machine. M. Foselli attempted only to discover some
practical way of determining the point above which the aeronaut is floating. He succeeded in his attempt on the i!6th of December; and on that day he communi- cated his method to M. Dumas, Secretary of the Academy of Sciences, and to my- self; but it was at that time absolutely necessary that it should remain a secret.
The method consists in drawing diago- nals corresponding to the 4 cardinal points upon the 4 faces of a sufficient number of towers or upon the roofs of churches, with large conspicuous letters, so that they may not escape the notice of the aeronaut provided with a field glass. Besides this, should be printed the name of the place.
By this means the aeronaut will know his place and the direction in which he is going ; again, knowing the time and dis- tance between two places, he can approxi- mately determine the velocity of his balloon. This method is ingenious and the only one sure to indicate to him his course through the sky. In presenting his project and plan to the Academy of Sciences, M. Foselli had but one end in view; that of paying to France, the coun- try of his adoption, the debt of gratitude for the immense service rendered his native land, Venetia, in delivering it from a foreign yoke. " I would buy," said he, " with my blood, the honor and good fortune to aid in the deliverance of Paris and France. Let my efforts be taken as tokens of my devotion."
He had constructed a model of his ma- chine of sufficient scale to resolve a great number of problems relative to progres- sion in the air; and he is certain that in a very calm atmosphere, a motive force re- latively feeble, like that of the hand of a man acting upon a screw of small diameter, could move a load of several hundred kilograms supported by the aerostat. Besides, he has discovered an unexpected fact which may lead to the means of navigating against the wind, or force the wind itself to give the machine a motion different from its own. He had suspended his model and had fixed to it two screws of like form and dimension, but mounted so as to act in opposite directions. These were set in motion by the descent of a weight. Who would not have supposed
VAN NOSTRAND'S ENGINEERING MAGAZINE.
that under the action of these two screws, opposite in direction, equal and of con- trary signs, the apparatus would have re-
mained at rest ? Yet it moved with a velocity greater than that due to the action of a single screw. These curious
results suggested to M. Foselli the happy I above) by means of which one can illustrate thought of converting his model into an j a great number of phenomena relative to instrument (of which a figure is given I the motion of bodies in fluids and gases.
-SOLAR HEAT
ITS INFLUENCE ON THE EAETH'S EOTARY VELOCITY.
By CAPTAIN JOHN ERICSSON. (Continued from page 565.)
Illustrations and descriptions have been prepared explanatory of important modifications of the dynamic register de- scribed in the preceding article adopted in order to control the irregular resistance of the atmospheric air against the rotating sphere, unavoidable in employing gas- flames for heating the equatorial belt ; ut the subject having already occupied
ore space than intended, I now propose state only the result of the experiments
hich have been made with the modified instrument, the dimensions of which, it should be observed, have been considera- bly increased ; the motive power, how- ever, remaining unchanged. It is scarcely necessary to remark, that a complete de- monstration and record of an investigation of this complicated nature would present an array of figures inadmissible in these columns. The accompanying diagram has, therefore, been devised to dispense with figures ; the relations of time, veloci-
ty, and resistance, being presented in such a manner that, among other facts, the amount of mechanical energy which dis- appears during the experiment, may be ascertained by mere inspection. For the purpose of saving space and facilitating direct comparison, this diagram has moreover been so arranged that the record of the experiments in which heat and refrigeration have been employed, is placed on the same base line with the record of the experiments in which differ- ence of temperature was prevented. The divisions on the base line, a b, mark the time of rotation, the large spaces indica- ting minutes and the smaller divisions 10 sec. each. The length of the ordinates of the curve, c b, resting on the base line, represents the number of turns performed in a given time when the rotating sphere is not subjected to the action of heat and refrigeration ; while the length of the ordinates of the curve, d e, represents the
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number of turns when heat and cold are being applied. It will be readily perceiv- ed that, lor instance, the ordinate between I and the curve, c b, represents the num- ber of turns per minute at the commence- ment of the second minute, while the ordinate 2 represents the number of turns per minute at the commencement of the third minute, and so on for all the other ordinates.
The permanent friction of the instru- ment, i. e.,the friction of the pivot on which the sphere turns, being practically inappreciable, it will be evident that the resistance opposing the rotation will vary in the ratio of the square of the velocities. Hence, as the respective ordinates be- tween the curves, c b, and d e, and the base line, represent the velocities, it will only be necessary to square these ordi-
11191 JiiSl -
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SMvJ:3!E!ISKSi;Si:JiSJDejlril8;;i;i-;r:--;'SlE£B^
nates in order to determine the exact amount of resistance to the periods indi- cated by the divisions on the base. Ac- cordingly, the ordinates mentioned have been prolonged in the ratio of their squares, the curves,/ b and g e, being the result of this prolongation. Obviously, the lengths of the ordinates of these curves resting on the line, a b, represent accurate- ly the amount of resistance opposed to the rotation of the sphere at the times indica- ed by their intersection with that line. The rate of velocity, i. e., the number of turns per minute, performed by the sphere at the commencement and at the termina- tion of each minute, will be found by re- ferring to the figures marked on the ver- tical lines,/ a and I b. Thus, for instance the rate of velocity at the termination of the seco d minute is 75.4 turns, when re- frigeration is not applied; while the rate is 68.0 when the cooling medium is ap- plied at the pole. As might be expected from the irregular nature of the external resistance opposed to the rotating mass,
the curves,/ b and g e, do not correspond with any of the conic sections. The avail- able motive power of 2,540 foot-grains expended during the experiment, is repre- sented by the superficies, fab; the energy developed being represented by the superficies, g a e. Assuming the former to be 1.000 the latter as shown by our diagram will be 0.763, difference=0.237; hence the amount of lost energy is 0.237 X2540=601.98 foot-grains. Now if the weight of water which is condensed at the pole and returned to the equator, multi- plied by the height necessary to generate the rotary velocity acquired during the transit,should amount to 601-98 foot-grains, the fact will be established that the cur- rent of vapor has not, during its passage from the equator to the pole, restored any of the energy abstracted from the sphere by the current of water flowing in the con- trary direction. The quantity of water condensed and returned to the equatorial belt being readily ascertained by observing 1 the increment of temperature of the con-
10
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tents of the polar cistern, it is easy to show that the energy abstracted from the rotating mass by the water thus trans- ferred from the pole to the equator, cor- responds so nearly with the differential me- chanical energy represented by the super- ficies,/^ eb, that the compensation result- ing from the tangential force exerted by the particles of the currents of vapor against the surface of the sphere of the dynamic register, is practically inappre- ciable; precisely as we find that the com- pensating tangential force of the currents of vapor which sweep over the basin of the Mississippi from west to east (neu- tralized by the currents which pass from east to west) is an inappreciable fraction of the retarding energy of 19,336,000,000 foot-pounds per second, exerted by the water which the Mississippi carries in the direction of the equator.
Having thus analyzed the opposing energies called forth by the waters flow- ing towards the equator, and of the re- turning vapors, the condensation of which reiDlenishes the river basins, we may now enter on a computation of the aggregate amount of the retarding energy, and the consequent diminution of the rotary velo- city of the earth, caused by the rivers enumerated in the Table accompanying a previous article. The total of the retard- ing force entered in the last column of that Table, it will be found, amounts to 53,857,788,300 foot-pounds, per sec, which sum multiplied by 8G,400 sec, shows that the earth has to overcome a resistance of 4,653,313X10& foot-pounds during each revolution. Multiplying this resistance by 36,524 days, we ascertain that the re- tarding energy of the water transferred in the direction of the equator by the en- tire Southern river systems of both hemis- pheres, amounts to 16,995,760,069X1010 foot-pounds in a century. Now, in order to determine the diminution of rotai-y velocity consequent on this counteracting energy, it will be indispensable to compute the earth's rotary vis viva. The elements necessary in this computation are, volume, time of revolution, specific gravity, and the position of the centre of gyration of the rotating mass. The two first-named elements are known with desirable ac- curacy; the third element, specific gravity, has been ascertained with tolerable ac- curacy; but the position of the centre of gyration, which depends on the internal
temperature of the globe and the disposi- tion of its constituent parts, has not yet been determined. Physicists assume that the density of the globe increases towards the centre in arithmetical progression; but this assumption is not sustained by sound reasoning. Our space not ad- mitting of discussing this complicated question at length, let us merely consider the leading fact, that, at a distance of only Jg- of the earth's radius=l, 044,400 ft. from the surface, the weight of a super- incumbent mass of fused granite, will ex- ceed 900,000 lbs. to the sq. in.=60,000 at- mospheres. Under this pressure the weight of air will be 70 times that of water, and 3.5 times that of the heaviest metals. Gold, at the point of fusion, is 7 times heavier than fused granite, while neither of these solids loses more than -j^-jj of specific gravity at melting heat; a fact which proves conclusively that high temperature of metals and minerals is not incompatible with great density. Hence, fused granite, in the earth's interior, may be many times heavier than the cold, mineral at the surface. Unless, therefore, we are prepared to dispute the assump- tion that fused granite under a pressure of 900,000 lbs. to the sq. in. will have its specific gravity doubled — involving a den- sity less than one-third of fused gold not subjected to compression — we must ad- mit that the specific gravity of the earth at the depth of ■£$ of the radius, is so great that, if the density, as physicists have assumed, increases in arithmetical pro- gression towards the centre, our planet would be many times heavier than it is. We are compelled, therefore, to reject the accepted theory; more especially as the stated enormous pressure consequent on superincumbent weight, takes place at only -gV of the earth's radius below the surface.
In accordance with the foregoing rea- soning, our computation of the earth's rotary vis viva will be based on the as- sumption that the mass is homogeneous. It is true that the specific gravity at the surface is somewhat less than one-half that of the entire mass; but we have shown that at a depth of ■£$ of the radius from the surface, the density is so great that if it continued to augment in arith- metical progression, the specific gravity of the globe would far exceed that which has been determined by careful investigation.
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Nor should we lose sight of the important fact, that the temperature corresponding with the compression produced by the superincumbent weight, is so great that the component parts of the central mass may be as light as pumice, notwithstanding the enormous external pressure. Conse- quently, it may be satisfactorily demon- strated that the earth's circle of gyration extends considerably beyond, in place of being within that of a homogeneous sphere, agreeably to the accepted theory of aug- mented density towards the centre. In our' computations, however, we will as- sume that the circle of gyration is that corresponding with homogeneity, which, in accordance with the property of spheres, is 0.6326 of the great circle. Sir John Herschel's determination shows that the mean diameter of the earth consider- ed as a perfect sphere is 7912.41 statute miles, or 41,777,524 ft. ; hence if we as- sume the specific gravity to be 5.5 we can readily calculate that the weight is 1,308,- 608X10 19 lbs. Multiplying the equa- torial velocity, 1519.07 ft. per second, by 0.6325, we ascertain that the mean ro- tary velocity of the entire mass of the earth is 960.81 ft. per second ; a rate ac- quired by a fall of 14,424 ft. The earth's rotary vis viva will accordingly amount to 14,424X1,308,608X1019=18,875,361X1022 foot-pounds. The mind being utterly in- capable of conceiving this stupendous energy without comparison with mechani- cal energies of less magnitude, let us ascertain to what extent it will be dimin- ished by the retardation exhibited in the Tables previously presented, namely, lO^S^O^OXJO1 ° foot-pounds,exerted in the course of a century by the south- ern river systems of both hemispheres. Dividing the stated retarding energy in the
,,, ■ • ,, 18,875,361xl022
earths vis viva, thus : rB>9},5>760>06t>xl()1o,
we find that notwithstanding the enor- mous amount of retardation exerted in a century only jrorAnnnnr of the rotary energy of the earth will be destroyed in that time. And if we multiply the fraction thus presented, by 10,000, we learn that at the end of 1,000,000 years, the rotary energy of the earth will be only tttV 6ir ^ess than at present ! By no other comparison, probably, than the one we have instituted, could we clearly compre- hend the magnitude of 18,875, 361X1022 foot-pounds of mechanical energy.
Let us now calculate the effect of the tabulated resistance, on the earth's rotary velocity, with reference to lime. The re- tardation observed by astronomers being as before stated, about 12 sec. in a cen- tury, our object will be to ascertain how far this retardation may be attributed to the counteracting energy under consid- eration. Multiplying, then, the number of seconds in a century, 3,155,673,600 by the retardirg energy of 53,857,780;300 foot-pounds per second, entered in the Table, we establish the fact before advert- ed to, that the total retardation is 16,995,- 760,069X1010 foot-pounds in one centu- ry. Dividing this retardation in the vis viva, it will be seen that the earth loses frnrfcjnir of its rotary energy in the course of 100 years ; but in calculating the time corresponding with this loss, we have to consider that the velocities are as the square root of the forces, and that, conse- quently, the rotary velocity will not be reduced as rapidly as the rotary energy. Evidently, if the diminution of energy and velocity corresponded exactly, the retar- dation of the earth's rotary motion during
., , 3,155,673,600 _ one century would be , 11A .,,„ ..,,, = -a.- J 1,110,01)2,343
8414 sec. But in accordance with the laws of motion referred to, the diminution of velocity during the century, will be in the ratio of the square roots of the earth's vis viva at the beginning and at the termination of that period. Now this ratio being readily computed, as wre know the amount of energy lost in one century while the time in seconds is also known, we are enabled to show by an easy calcu- lation that the earth suffers a retardation of 1.42071 sec. Adding the retardation occasioned by the tabulated sedimentary matter=0. 00105 sec. ascertained in the manner explained, the total retardation of the earth's rotary velocity in a century, at the present epoch, will be 1.42176 sec. The vastness of the rotary vis viva of the earth having already been discussed, it will not be necessary to offer any explana- tions with reference to the insignificance of the stated retardation, in comparison with the magnitude of the counteracting energy exerted by the water and sediment of the entire river system presented in our Tables.
We have now to consider the influence on the earth's rotary energy exercised by rivers, the course of which is in the direc-
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tion of the poles. Evidently river water running- from the equator, will have its motion round the axis of rotation, con- tinually diminished as it reaches the northern parallels ; hence rotary energy will be imparted to the earth by all rivers flowing towards the poles. At first sight, it will be imagined that the energy thus imparted will neutralize the retarding force exerted by the waters transferred towards the equator. Certain physical causes, however, prevent the imparted energy from restoring any of the earth's lost vis viva. The subject will be most readily comprehended by an examination of the nature of the neutralizing force ex- erted by the following great rivers, namely, the Lena, Yenesei, Obi, and Mackenzie, which furnish the principal amount of water discharged into the Arctic Ocean. These rivers drain an area of t3,S40,000 sq. miles, the latitude of the centre of their basins, and their outlets, being very nearly in the same parallel. The mean of the former is 59 deg. 30 ruin., that of the latter 69 deg. 56 min. Accord- ingly the mean circumferential velocity of outlet is 421.18 ft. per second, while that of the centre of basin is 770.95 ft. per second. It will be seen, therefore, that a diminution of rotary velocity of 770.95 — 521.18=249.77, say 250 ft. per second, takes place during the transfer of the water from the centre of the basins of these rivers to their outlets. Now a ve- locity of 250 ft. per second is produced by a fall of 976. 5 ft., hence each pound of water discharged into the Arctic Ocean by the before-named rivers, will impart a mechanical energy of 976.5 foot-pounds. Apart from this powerful neutralizing force of a given weight, the quantity of water transferred is so great owing to the vast extent of the basins, that, notwith- standing the moderate precipitation in high latitudes, the rotary energy imparted to the earth will balance the retardation of the 136 rivers entered in our tables. It scarcely requires explanation that the stated enormous force exerted by the water transferred by the great northern rivers, is owing to the rapid diminution of rotary velocity in approaching the pole ; a single degree of latitude at the point where, for instance, the river Lena dis- charges into the Arctic sea, having a great- er fall than ten degrees have within the tropics. It would be waste of time, how-
ever, to compute the exact amount of energy imparted to the earth by the Arctic rivers, as will be seen by the following examination of the subject. Unquestionably, if the supposed pound of water on entering the Arctic Ocean at once evaporates and ascends into the atmosphere, we must admit that an impulse of 976.5 foot-pounds has been imparted to the earth by its transfer from the centre of the river basin; but, if it should be found that in place of evapora- ting on entering the cold polar sea, the pound of water commences a retrograde motion towards the equator through Beh- ring's Straits or through the wide chan- nel between Norway and Greenland; and if we should find also that when it crosses the 59 deg. 30 min. parallel (the same as that of the centre of the river basin) it has not yet been converted into vapor, we must then admit that the whole of the energy imparted to the earth by the approach to- wards the axis of rotation, during the original transfer to the polar sea, has been completely neutralized by the retardation consequent on the retreat from the axis of rotation, during the southerly course to the last-mentioned latitude. Following our pound of water during the continu- ation of the motion towards the equator, we^may discover that it has not changed its form into vapor even when reaching lati- tude 47 deg. 45 min., at which point the cir- cumferential velocity is exactly 250 ft. per second greater than that of the centre of the basin from whence the motion pro- ceeded. In that case, not only has the imparted energy been neutralized, but a retardation of 976.5 foot-pounds has been called forth by the pound of water, the course of which may possibly continue until it mixes with the warm water within the tropics. Let us guard against con- founding the movement of the water dis- charged into the Arctic sea by the north- ern rivers, with the currents produced by the combined influence of lunar attrac- tion, winds, differential oceanic tempera- ture, and solar attraction. It has long been recognized that the water poured into the Arctic sea by the great Asi- atic rivers, is the result of condensation of vapors raised by the sun within, or near, the tropics. A corresponding amount of water must, therefore, be re- turned from the polar sea, or its surface would be elevated, and that of the tropic-
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al seas suffer a proportionate depression. The reader cannot fail to perceive the im- portant bearing of these facts on the question of retardation of the earth's ro- tary velocity.
The result of the experiments with the dynamic register proves that the rotary motion possessed by the vapors on leav- ing the equatorial seas, may be almost entirely destroyed by being converted into heat during their course towards the basins of the northern rivers ; hence im- parting no perceptible tangential force to the earth. Accordingly, the return to the ti'opical seas of the water which is con- tinually being discharged by the northern rivers into the polar seas, will, on account of the increased velocity round the axis of rotation imparted during the southern course, subject the earth to an amount of retardation far exceeding that produced by rivers flowing towards the equator. It may be asked under these circumstan- ces, why the latter rivers have been tabu- lated, and their inferior retarding energy calculated. The rivers flowing in the di- rection of the poles have been examined, tabulated, and their counteracting energy calculated ; but the question of attendant retardation of rotary velocity cannot properly be entertained until certain other counteracting influences shall have been examined. The publication of the Table containing the southern rivers has been deemed necessary as a point d'appui facilitating demonstrations intended to establish the fact that, independently of the counteracting force of the tidal wave (hitherto greatly overestimated), the re- tarding energy called forth by the evapo- ration within the tropics, and the conse- quent condensation and precipitation in the temperate zones, fully account for the retardation of the earth's rotary velocity — 12 seconds in a century — inferred from the apparent acceleration of the moon's mean motion.
P. S. — Referring to the solar pyrome- ter, some misapprehension appears to ex- ist concerning the indication of the focal thermometer. It is asserted that the loss of heat and consequent reduction of the temperature indicated by the focal ther- mometer, cannot, as assumed in our de- monstrations, lead to an overestimation of solar intensity. A moment's reflection, however, will show that, agreeable to the adopted mode of computing solar inten-
sity, increase of the temperature which is imparted to the focal thermometer by a radiator of given intensity will cause cor- responding reduction of the deduced solar intensity. It was demonstrated in the article relating to the concave spherical radiator, that the sun, notwithstanding its size, is not capable, owing to the vast distance, of transmitting to the earth more than -jgVo °f the temperature which the incandescent radiator transmits to its focus, equal intensity of radiant heat being assumed. Hence, it was inferred that the temperature of the sun must be 3,019 times higher than that of the ra- diator in order to transmit to the boundary of the earth's atmosphere as high a temperature as that transmitted by the radiator to the focal thermometer, viz., 117.2 deg. But the temperature pro- duced by the sun's radiant heat at the said boundary being only 84.84 deg., it was shown that the radiant power need not
be more than yrnr — = 2619.76 times
greater than that of the incandescent radiator, in order to produce a tempera- ture of 84.84 at the atmospheric boun- dary. The temperaturej of the radiator during the trial of February 4, 1871, was 1099.39° ; consequently 2619.76X1699.- 37°.=i,45 1,941° is the solar intensity deduced from a differential focal tempera- ture of 117.2 deg. Fahr. The actual tem- perature, however, transmitted to the thermometer placed in the focus of the incandescent radiator, during the trial re- ferred to, was, it will be seen by reference to the Table, 157.83 deg. Now, compari- sons with experiments conducted in vacuo, have shown that when the heat trans- mitted by radiation reaches 160 deg., in an atmosphere of 40 deg., the loss oc- casioned by exposing the thermometer to the surrounding air will be fully 0.06 or 11 deg. This great reduction of tempera- ture is caused by the feeble energy of radiant heat compared with the powerful refrigeration produced by currents of air. We have accordingly to substitute 117.2° -j-ll°=128.2°, for 117.2° focal differen- tial temperature. Agreeable to the asser- tion the correctness of which we are going to disprove, the increase of focal temperature ought to show an increase of solar intensity. That the converse will result from increased focal heat will be in- disputably established by simply repeating
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the foregoing calculation, substituting the focal temperature 128.2 for that of 117.2°.
Thus
3G10 X 84.84 138.2°
= 2394.97 times greater
temperature of the sun than that of the radiator— 1699.37° Fahr.— will be requir- ed to cause an elevation of temperature of 84.84 on the Fahrenheit scale, at the boundary of the atmosphere. Basing our computation on the stated high focal temperature, we accordingly reduce the sun's temperature from 4,451,941°, to
1099.37° X 2394.97 = 4,069,940o. The fallacy of the assertion that diminution of focal heat cannot lead to an over-estima- tion of solar intensity, has thus been fully proved. At the same time we have shown that when due allowance is made for loss of focal heat, the solar temperature de- duced from the indication of the incan- descent radiator, corresponds very nearly with the temperature deduced from the indications of the solar pyrometer, viz., 4,063,984° Fahr.
ASTRONOMICAL OBSERVATION.
From " Nature.
The statistics of modern astronomical observation would, we suspect, be very curious, if it were possible to get at them. A report showing the gradual increase in the number of telescopes manufactured during the last fifty years would be very interesting; and so would be a table com- prising at once the advance in their di- mensions and the diminution in their cost. The result would, we believe, be such as at first sight to cause great surprise among those unacquainted with the sub- ject, or those whose recollection does not go back to days when five inches was as extraordinary an aperture for an object- glass, as double that size is now. But the value of these, as of other tabular statis- tics, would suffer material abatement, if they were applied to establish any other conclusions than those to which they directly lead. For instance they would probably be fallacious, if considered as inferring a proportionate increase in the number of important observations. In order to bring out such a result, we re- quire, so to speak, another factor, and a very essential one — a corresponding in- crease in the number of competent ob- servers. This, we fear, may not have been commensurate with the advance of optical means; at least, except upon the supposi- tion of some such deficiency, it is difficult to understand what becomes of the multi- tude of really good object-glasses which are annually produced, not only in Eng- land, but in Germany and America. A large proportion of these, we are led to think, must be purchased to be looked at, and not looked through, or handled as mere toys for the amusement of people
who do not know what to do with them- selves in an idle evening. This was not so much the case in the early days of telescope manufacture. The greatest master of figuring specula in his own time was also the greatest proficient in using them; it is needless to add the name of Sir William Herschel. And so the fine reflectors in Germany were placed at the same period in the hands of the leader of all accurate selenographical investiga- tions, J. H. Schroter. These were " the right men in the right place." Even then, it may be said, many noble reflectors went, no one knows where, the greater part of them long before this time useless from tarnish, or, still more mortifying to think upon, ruined by unskilful repolishing. Still, admitting this, the disappearance of powerful instruments does not seem to have been so remarkable in those days as it is now, and the quantity of really valua- ble observations appears to have been greater in the end of the last and the early part of the present century, in proportion to the means of observing.
This is not a very encouraging view of the present state of this branch of astronomy. Bnt, if well founded, as we believe it to be, we might expect that there would be some assignable reasons for it; and, in fact, several are sufficiently obvious. One certainly iSj that the pro- cess of discovery is not, generally speak- ing, renewable. What has been once de- tected is usually placed on record, in bar of all future claims. So it has been in the science of music; a man might arise among us with the fervid genius of Handel, but he could not write the Halle-
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lujah Chorus over again; and doubtless the spirit of Mendelssohn must have been cramped by the impossibility of employing many of the noblest and most impressive subjects which had been anticipated by his predecessors. And so it has been in the researches of geography. The enter- prising explorer has now to go much farther in pursuit of "fresh woods and pastures new," and every Alpine season is so rapidly narrowing the number of summits untrodden by the foot of man, that the excitement of a first ascent will soon have to be sought in remoter regions. Thus in astronomy, though it cannot be said that there are no worlds left to conquer, yet all the larger and more conspicuous features of the heavenly bodies have been long ago so fully noted and recorded, that what remains for exploration is chiefly of that delicate character which, without being the less interesting from its minuteness, is less accessible, for that reason, to the posses- sors of ordinary instruments. And on this account many a student who might well have risen from the ranks in the earlier days of scientific campaigning, is now compelled to remain in comparative obscurity — a mere spectator, when he might well have taken his place among the discoverers of fifty years ago.
Another reason why tools have multi- plied without a corresponding increase of good work, may be this, that looking upon the observer and his instrument as a com- plex apparatus, the improvement of the intelligent has not kept pace with that of the material part. In fact, it is impossi- ble that it should. The eye is but what it was when David learned humility from considering God's heavens, the work of His fingers, the moon and the stars, which He hath ordained; the intellect, though more developed and cultivated, is not more strong and piercing than it was in the days of Hipparchus; man does much more with his brain, but he has no more brain to do it with, than his uncivilized ancestors; and observers may, and will, be collectively multiplied without being individually improved. Every man that has eyes does not know how to use them; or, not failing in this respect, he may lack other requisites: he may not know what to look for, or where to find it; or he may be deficient in his handling of the faithful pencil or the expressive pen. And so it
comes to pass that the capacities of in- struments may be much in advance of the abilities of those who use them.
Besides all this, there is a physical ob- stacle of an entirely different character, which must not be forgotten, — the unim- provable constitution of our own atmos- phere. This will ever be a sore subject for the zealous observer, especially among ourselves. If even Secchi finds fault with the glorious Roman heavens, what have we not to regret in our own murky, and fuzzy, and restless skies ? Who that has read the most graphic as well as instruc- tive writings of Sir J. Herschel is likely to forget his complaints of " twitching, twirl- ing, wrinkling, and horrible moulding V and who that has had much actual ex- perience of observatory work will not en- dorse all this with a very lively fellow- feeling? The nights may easily be num- bered, during a long season, in which the defects of the atmosphere do not overlie those of the instrument, and when the observer has not rather to wish that he could see all that his telescope could show him, than to long for greater power or light, to be expended in making atmospheric disturbances yet more con- spicuous and prejudicial. The only way to obviate this grievous hindrance is to get above it; and no man has yet done this except Professor Piazzi Smyth in his most successful "Experiment;" it was said, in- deed, that the French observers were about to follow his example and to plant their instruments on the Pic du Midi de Bigorre; but we have never heard whether the idea has been carried into execution. And, however striking may be the ad- vantage of such a plan, it must ever be confined to a favored few.
We have dwelt at some length On a view of the present state of astronomical observation, which, though rather un- favorable, we believe to be substantially true. But it is not to be inferred that this is its sole aspect. There are, as usual, two sides to the shield; and much is to be said that is of an opposite tendency. If, for instance, we have asserted that for some time past observers have not multi- plied in proportion to the means of obser- vation, this is but a relative statement; the absolute fact is that at no former period has there been so numerous, or so zealous, or on the whole so competent a band of astronomical students. And of
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this we have a very pleasing evidence in the recent formation of an astronomical society expressly devoted to physical ob- servation, to which we cordially wish suc- cess. If, again, it is probable that not many of the great discoveries are left within the reach of ordinary instruments, it should not be forgotten that many telescopes of very superior character are now housed in private observatories; and that for them investigations are still reserved, whose delicacy is no bar to their importance, and which may be undertaken with a hope of success no longer chargeable with ex- travagance. Great cabinets may be un- locked by little keys. Minute researches may give the clue to discoveries of the broadest extent and deepest interest. The changes of the lunar surface; the internal motion of starry clusters; the parallax and fixity of nebulre; the planetary at- tendants on the brightest stars, these are mere specimens of the magnificent arcana, whose solution may not be denied to hu- man energy and perseverance. We may, remember, too, that if the telescope and the micromoter should be found unequal to the task, we have yet a new and most powerful method of investigation, the re- sults of which are equally important and surprising — spectrum-analysis. The reve- lations of this beautiful invention may be said to be only beginning, and no man can foresee their end. What has already been done would have appeared as im- probable as the reveries of Kepler, had it been predicted 50 years ago; and who shall say what may be the result of 50 years more of patient and energetic application ? And what might not Kepler have said and done, had such an instrument of research been placed in his hands ? We may sup- pose how his fervid imagination would have exulted in the pi'ospects, and with what confident joy he would have repeated the memorable words which characterize one of his lofty aspirations, " Plus ultra est."
The Weston Patent Smoke and Gas Con- suming Boiler Company. — This is the name of a new corporation formed to introduce the above-named boiler to the attention of railroad and steamship man- agers, engineers, master mechanics, and, in fact, to all using steam power. It is claimed for this invention that it will save
-^ the fuel used in the generation of steam, besides completely consuming all smoke and gas — facts which are vouched for by the South Side Railway Company of L. I. ; the Grant Locomotive Works, Pater- son, N. J.; by H. Anderson, late General Master Mechanic of the Chicago and North- Western R.R. Company; the Super- intendent of the Vulcan Iron Works, Buffalo, and several other prominent establishments where this boiler has been thoroughly tested and in successful opera- tion during a year past.
The annual product of pins in the United States is 2,000,000 packs, each pack containing 3,300 pins, or a total of 6,720,- 000,000 of pins. This terrible quantity is the yield of 8 pin factories. One manu- facturer's agent in Boston, according to the " Bulletin," sells every 6 months 1,000 cases of pins, each case containing 672,000 pins. The factory represented turns out 8 tons of pins per week. Hair pins are jobbed by the cask, and but one factory makes them, but that at the rate of 50 tons per month. The machine which cuts and bends the wire, makes 360 hair pins per min., ready for japanning. The pro- duction and consumption of pins increases 10 per cent, annually. A great part of the hair pins used are imported. After these figures, we can safely ask, What be- comes of all the pins ? — Iron Age.
¥hat is Navigable Water? — A recent important decision of the United States Supreme Court establishes that a river is a navigable water of the United States when by itself or in connection with other waters it forms a continuous highway, over which commerce is or may be carried on with other States, or with foreign countries, in the customary modes in which such commerce is conducted by water. If a river is not of itself a high- way by its connections with other water, and is only navigable between different places within the State, then the Court holds it is not a navigable river of the United States, but only a navigable water of the State. This is clear enough, and is worth making a note of.
California has 2,307 miles of railway, and is far above some of the older States.
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ON RECORDING EARTHWORK NOTES.
By H. KOCH, C. E.
Every railway engineer knows how im- portant it is to have earthwork recorded in such a manner as to show, without calculation, what quantities either of embankment or excavation, whether of borrow or waste, lie between any two sta-
tions. We offer here a simple device to accomplish this end.
Represent the stations on an absciss line, the earthwork quantities by ordi- nates, commencing with 0 at station 0, and representing the quantity of earth-
Explanation
Total work to be done represented by outside curve. From station 0 to 1, 1200 yds. cut. 0 to 2, 2340 0 to 3, 3000
0 to 3 + 20, 3030 yds. cut. At 3 + 20, beginning of filL From station 0 to 4, 2800 cb. yds. cut. 0 to 5, 1420 " " 0 to 5 + 90, 0" Between 0 and 5 + 90 cut and fill are equal. Between 0 and 6 or 5+90 and 6, 200 cb. yds. fill. 5+90 and 7, 1180 " " 7+40, 1300" " At 7+40 fill changes into cut. Between 5+90 and 8, 1060 cb. yds. fill.
8 + 60,0" " " Between 5 + 90 and 8 + 60 cut and fill balance each other. Between 8+60 and 9, 480 cb. yds. cut.
10. 650 " " " This cut to be wasted on account of obstruc- tion. Between 11 and 12, 320 cb. yds. cut.
work between this and the next station by an ordinate at the latter. Excavation is to be represented by measurements upwards, or by an increase of ordinate, and embankment in the opposite direc- tion.
Vol. V— No. 1.— 2
of Engraving.
Between 11 and 12 -f 95, 0 cb. yds. cut.
Betwen 12 + 95 and 14, 320 cb. yds. fill.
Between 11 and 12, 600 yds. side cut and 280 side filL
Between 12 and 12 + 95, 600 yds. side fill and 280 side cut.
The work of two different months is represented by the proper curves.
"On first month, between 1 + 35 and 4 + 90, 1100 cb. yds. cut, worked in to fill ; 350 cb. yds. left to be done yet.
Between 5+90 and 8 + 60, 420 yds. cut, worked in to fill ; 780 left undone.
Between 8 + 60 and 10, 450 cub. yds. cut wast- ed; 200 yds. left.
On second month 1000 cb. yds. are taken from cut between 0 and 1 + 35 to fill between 4 + 90 and 5 + 90; work between 1 + 35 and 4 +90 completed; 600 cb. yds. cut and fill left un- done between 0 and 5 + 90.
Between 5 + 90 and 8 + 60, 220 yds. are moved from cut to fill and 600 left undone..
Between 8 + 60 and 10 work completed with 200 yds. cut, wasted.
If the extremities of the ordinates to a series of stations be connected by a curve line, the points where cut and fill balance will be shown by the intersection of the curve and the abscissa. The maximum points will show where cut changes to
18
VAN NOSTRAND'S ENGINEERING MAGAZINE.
fill, and the minimum where fill changes to cut. A break in the curve either above or below the absciss line, indicates the necessity of wasting or borrowing respec- tively at that point.
The scale for the whole may be made convenient to the amount of work.
The work of different months over the
same line may be represented by curves of different colors or shades.
The labor of drawing the above is very slight ; the curve may be drawn on the same sheet as the length profile.
The accompanying sketch of a record of an imaginary earthwork will serve to explain the plan more fully.
LITHOFRACTEUK.
From " Engineering."
Those of our readers who have followed us in our series of articles upon the sub- ject of explosive compounds will be aware that we have many which possess great power for work, but which are unsafe to manipulate. They will also remember that the aim has been for some years past to tone down the violence of these com- pounds either by effecting new combina- tions of old materials, or by introducing new oues, so as to combine perfect safety in handling, transit and storage, with thor- ough efficiency in action. The principal practical results which have accrued have been the production of gun-cotton and dynamite, the use of the latter being con- fined to the Continent, chiefly on account of the existence in England of the Nitro- glycerine Act, which virtually prohibits the transport and storage of compounds into the composition of which nitro-glycerine enters. Within the last week, however, we have had to add another to our list of safe yet violent explosives tried in Eng- land, and which bears the name at the head of the present article. Lithofracteur — literally stone-breaker — is the patented invention of Professor Engels, of Cologne, and is composed of nitro-glycerine as a base, gun-cotton, the constituents of gun- powder, some chlorates, and an infusorial earth. These substances are prepared in a special way, and blended together by special means, the details of these opera- tions being known only to the inventor and the manufacturers, Messrs. Gerbruder, Krebs & Co., of Cologne. The result of this combination is a black compound of the consistence of soft putty, which is made up into paper cartridges 4| in. long by £ths of an inch in diameter, and weigh- ing If oz. each. "When lighted in the air by ordinary means it simply burns out, leaving a light white powder as a resi-
duum; but when it is ignited either in the air or in a closed chamber with a capped fuse, its full violence is developed. It is safe under all ordinary and even extra- ordinary circumstances of storage and transit, as recent experiments in England and lengthened use on the Continent have proved. And here we may mention that, although this is almost the first time we in England have heard of this substance, it has been made and extensively used throughout Germany for more than two years past. It was used by the Prussians against the French during the recent war, Herr Engels being the operator. After Fort Issy was taken the Prussians destroy- ed a number of French heavy siege guns by blowing off their muzzles with litho- fracteur.
A notice of this material having appear- ed in the German papers, the attention of the mining world in England was attracted to it, and a correspondence ensued be- tween the manufacturer and Mr. R. S. France, the lessee of some extensive quar- ries in England. The result was that ar- rangements were made for testing the new material, Mr. France offering the use of his quarries, and Messrs. Krebs carry- ing out the experiments. In order that full publicity might be given to the trials Messrs. Krebs invited the attendance of a number of scientific gentlemen, who met at Paddington on Monday morning last, and proceeded to Shrewsbury, near which town Mr. France's quarries are situated. The party consisted of Captain Harvey, R.N., the inventor of the torpedo bearing his name, Captain McEvoy, of the London Ordnance "Works, Mr. Brown, of the chemical department at "Woolwich Ar- senal, who represented the Government upon the occasion, Mr. Cargill, C.E., and Messrs. Houlder, Hockin, Comyn,
VAN NOSTRAND'S ENGINEERING MAGAZINE.
19
and Farrell, gentlemen connected with mines at home and abroad. The experi- ments were conducted by Herr Engels, assisted by Mr. Perry, F. Nursey, C.E., who is the engineer, in England, to Messrs. Krebs & Co., the arrangements of the trip being excellently carried out by Mr. Kirk- mann, of Cologne, on behalf of Messrs. Krebs. The experiments were com- menced on Tuesday morning at the Nant Mawr quarries, which are about 23 miles from Shrewsbury. These quarries are being worked in a range of carboniferous lime- stone mountains extending from 20 miles to the west of Shrewsbury northwards to the coast. The workings are approached from the railway by a double tramway 500 yards long, laid at a gradient of 1 in 8 up to the summit. Here the 2 lines branch off into 15, running to the face of the work. The wagons of limestone are sent down the incline by gravitation, the full trucks bringing up the empties. The limestone is of a very fine character, and is much used in iron works as a flux, the top portion being burnt for lime, Mr. France having 16 kilns for that purpose, which he keeps well employed.
The preliminary experiment consisted in throwing a box containing 5 lbs. of litho- fracteur from the top of the quarries at a height of a 150 ft. from the ground into the plateau below. The box was smashed and the cartridges were scattered about, but not one was exploded. A cartridge was then lighted by an ordinary fusee, when it burned slowly out. Another car- tridge was then placed upon a block of stone and fired with a percussion fuse, when a violent report followed, and the top face of the stone was broken off. The power of the lithofracteur when confined was then exhibited by firing charges in the bore-holes of several blocks of stone, which were shattered into many frag- ments. The tamping in all cases was effected with water, thus proving the use- fulness and reliableness of the compound in workings where wet ground was met with. Another point also proved was, that if a misfire should occur — and one or two did occur in the course of the experi- ments— the charge could be withdrawn — and another one inserted without re- moving the tamping. And here we may explain that the method of firing is similar to that adopted by Nobel with dynamite and Abel with pulped gun-cot-
ton. The capped fuse is simply imbedded in the lithofracteur, the paper of the car- tridge being tightly tied round the fuse. The next part of the programme consisted in firing a number of shots, both horizon- tal and vertical, in the face of the quarry. As these were more or less repetitions of each other, we need only notice a few of them, although they all gave extraordinary results. The holes were mostly bored under the direction of some of the mining gentlemen present, who, with the view of testing the compound to the utmost, selected the worst possible spots, some of which, they stated, gunpowder would not possibly touch. The first of these blasts was made with a 1 lb. 1| oz. of lithofrac- teur placed in a horizontal bore hole 3 ft. 4 in. deep, and 1| in. in diameter. A large quantity of the stone was blown out to the front, and the face of the rock was scaled and cracked over an area of 20 ft. 6 in. wide by 13 ft. high. A couple more shots were then fired simultaneously near to the last, the bore-holes were each 3 ft. deep, and were charged with 13| oz. and 1 lb. \ oz. respectively, and an immense face of rock was brought down. The best blast, however, was the last of this series ; it was fired in a vertical bore-hole, 4 ft. 6 in. deep, on a ledge of rock, about 23 ft. from the level of the plateau below, 1 lb. 1| oz. of lithofracteur being used. The explosion brought down at least 20 tons of z*ock, and loosened an enormous mass behind the bore-hole, the shot being one of the finest we ever saw with so small a quantity of material.
Some experiments were next made with the view of showing the disruptive effect of lithofracteur on iron, and for this pur- pose a 4 ft. length of 75 lbs. double-headed rail was laid on its side, being supported at each end at a height of 3 in. from the ground. A charge of 1 lb. 3 oz. of the compound Was placed in a lump on the eentre of the rail, and tamped with paper, three old sleepers being placed on the tamping, and fired with a percussion fuse. A startling report ensued, the fragments of the sleepers being sent in all directions, and on examination the rail was found much bent, and with one head cut through, and 11 in. of the web blown away in the centre. Had the supports been a little higher, so as to have left room for a greater angle of bend in the rail, both heads would doubtless have been cut
20
VAN NOSTRAND'S ENGINEERING MAGAZINE.
through. The experiment was then re- peated with two similar lengths of rail to the last, placed one on the other on their sides, the charge being 1 lb. 5 oz. of litho- fracteur. The under rail was 6 ft., and the upper piece 3 ft. 6 in. long, the height of the supports being increased to 1 ft. 6 in. Five pieces of old sleeper were placed over the charge, which, when fired, hurled them with a cloud of dust high into the air, scattering the debris far and wide. Both the rails were broken clean through, the halves being thrown far away from each other. The under rail was also ci'acked through both tables on one side. So far, with the exception of one or two experiments at the first, the power only of the lithofracteur had been put to the test. It was now proposed to carry out an idea, which originated with Mr. France, to put the compound to the severest possible test in order to prove its behavior under the conditions of a railway collision. To this end he had an old railway wagon placed on the rails at the bottom of the incline, whilst at the top was another, in front of the buffers of which were fixed two cartridges, one on each buffer. Each wagon weighed about 1| tons, the buffers of both being of wood. The upper wagon being released, started on its journey of 500 yards on an incline of 1 in 8, the speed being of course very great when it reached the bottom. On arriving there the buffers fairly met, and both wagons were in a few seconds lying a heap of splinters and fragments, wood and iron being alike smashed up. On examining the wreck the lithofracteur was found smeared on the buffer heads and other parts of the wagons. No explosion having of course occurred. The possibility of an explosion in a collision, should two iron surfaces, or even an iron and a timber surface meet, was then suggested by Mr. Brown of the Royal Arsenal, and Mr. France, in a most spirited manner, ordered the experiment to be repeated, with the buffers of the up- per wagon iron-plated. The iron-on-iron test was carried out by tying two car- tridges on the top surface of each rail at a point about 50 ft. above the foot of the incline. Upon the upper wagon being released, it went on its way down the in- cline, but had only reached about half way when its high velocity caused a wheel to break, and the wagon went smashing and spinning over a steep embankment
into the meadows below. No explosion occurrred here, but the party were un- expectedly gratified by witnessing the representation of another class of railway accident.
Nothing daunted, Mr. France ordered out another victim to scientific research, and a fifth wagon was doomed. The buf- fers were iron-plated, and the cartridges were fixed in front of them as before. When once started from the summit of the gradient it rushed downwards, passing in its course over the cartridges on the rails. Two semi-explosions occurred, such as would be produced by striking a percussion cap with a hammer on an anvil. When the descending wagon reached the stationary one it smashed into it, and they toppled over together, another slight explosion being heard. The buffer plates were found some feet from the line, with pieces of the cartridge paper and some of the lithofracteur adhering to them, por- tions also being spattered over other parts of the framing. On examining the rails the greater portion of the compound was found to have been spurted about, one of the cases remaining tied to the rail, and the other having been carried some yards down the line. The explo- sions were occasioned by the ignition of that portion of each cartridge exposed to the force of impact, the remainder not having been exploded nor burned. This is borne out by the fact that on one rail we found a smear of lithofracteur, 7 ft. 6 in. from the cartridge case, in the centre of which was a small white spot. A careful examination of this spot proved it to be exploded lithofracteur, and 7 ft. 6 in. being the exact circumference of the wheel at the tangent of its cone with the rail, there could be no doubt that the wheel had picked up a piece of the com- pound, and, on completing its next revo- lution, deposited it on the rail, an almost inappreciable portion exploding at the • point of contact. These experiments con- cluded the day's proceedings, after which the party returned to their headquarters at Shoeburyness. The experiments were resumed on the following day at the Breidden quarries in a different kind of stone, and some submarine experiments were also carried out, but want of space obliges us to defer a notice of these until next week.
Mr. France's object in having these last
VAN NOSTRAND'S ENGINEERING MAGAZINE.
21
experiments made was to test the effects of concussion upon lithofracteur. He con- sidered this essential, in order to meet the objections raised by railway companies to the transit of explosive compounds, and he deserves the thanks of all interested in mining matters for the convincing manner in which he has demonstrated the harm- less character of lithofracteur. The great drawback in many cases at the present
time to efficient mining and quarrying is the lack of such substances as these, which above all others are calculated to promote the development of this class of property. It is to be hoped that the stringency of the Nitro-glycerine Act will be somewhat re- laxed, now that that dangerous substance has been proved to be so safe and harm- less under all possible conditions except those of actual work.
THE EELATIVE VALUE OF DIFFEEENT KINDS OF FUEL.
Prom the " Colliery Guardian."
The evolution of force by heat, with motion as a resultant, is one of the most important of the laws of natural philos- ophy. Wherever motion occurs, heat must be recognized as the primary cause. The sum is the original source in the pro- duction of heat, as shown by its influence upon tides, winds, and the support of the life of plants and animals. Its effect is curiously displayed on the natives of the tropics, in supplying them with such sus- tenance by natural heat as to make very little food requisite ; whilst towards the frigid zone, the use of carbonaceous food becomes more and more necessary. The elements hydrogen and carbon, in com- bination with oxygen, evolve a greater amount of heat than any other elements. As hydrogen is not attainable, substances such as wood, peat and coal, which con- tain a large proportion of carbon, are chosen as the materials which by com- bustion produce heat. In the construc- tion and building up of organic life, a certain amount of energy is invested by the sun's rays. In combustion this en- ergy re-appears as heat. This, in a few words, is the true theory of heat. The more a substance is capable of absorbing and rendering latent a certain number of units of heat, the more it is capable of giving out. when consumed with oxygen, appreciable and useful energy.
It is important to observe the compar- ative results available from what may be termed " current-going " heat, as de- veloped by the work of a horse, and conserved heat, as shown in the work done by the combustion of fuel. This is demonstrated by the fact that the combustion of a single pound of coal in one minute is equal to the work
of 300 horses for the same time. The extent to which any country is influenced by the possession of coal fields is evi- denced by the following singular state- ment : Taking 10 lbs. of coal per day, or 1| tons per year, as applied to the pro- duction of mechanical power through the agency of steam, to be equal to the labor of a man, every 10,000,000 tons of coal adds to the productive labor of England, a force equal to the exertion of 7,500,000 fresh men annually. A beautiful exam- ple of nature's constant law of "' no waste " is afforded in considering the combustion of fuel. The exact amount of carbon which is set free by combustion, either of fuel or animal life, is again stored up in animal vegetation. The results of com- bustion, viz., carbonic acid and water, return to the earth to support the life of plants and trees, which absorb the car- bon from the carbonic acid, setting free the oxygen again for the support of life or combustion, and obtain hydrogen 'from the water in the atmosphere. Each ele- ment retains its calorific power, and thus the fuel of the future is undergoing a constant process of formation from the results of the combustion of the fuel of the present.
A brief description may now be given of the different varieties of fuel used in the British Islands.
Table I.
Name. Where found.
1. Wood
2. Charcoal
3. Peat Ireland and moorland districts.
4. Lignite Germany and Devonshire.
5. Bituminous coal All English coal fields.
6. Anthracite Wales.
7. Coke
I. "Wood. — This is the original form of
22
VAN NOSTRAND'S ENGINEERING MAGAZINE.
fuel. The objections to its use are, first, the comparative small amount of carbon it contains, varying from 40 to 53 per cent. ; second, the amount of moisture it generally contains — the value of damp wood being -^ less than dry ; third, the surplus of oxygen it contains, which re- tards combustion. Wood is only used as fuel when it is abundant and coal is scarce.
II. Charcoal. — Charcoal is wood freed from its volatile ingredients. Owing to the scarcity of wood and inconvenience of manufacture, charcoal is only used as fuel when coal is scarce, or when a hot fire is desired in small compass. It is more pure than coal, but absorbs mois- ture to the detriment of its heating power. The following is a scale of the compara- tive heating value of different woods be- fore and after being made into charcoal, No. 1 being the best :
Table II. Wood. Charcoal.
1. Fir Oak.
2. Poplar Birch.
3. Birch Poplar.
4. S vcamore Fir.
5. Ash Elm.
6. Elm Sycamore.
7. Oak Ash.
There is much more variety in the wood than in the charcoal, the former varying from 1,000 to 790, and the latter from 1,000 to 985.
III. Peat. — Peat, resulting from the decomposition of vegetable matter in marshes, has about f the heating power of coal, and is used almost solely in the localities where it is found. It is diffi- cult to obtain it free from earthy particles.
IV. Lignite. — This is an imperfect coal formed by wood buried in moist earth, and thus undergoing one of the changes leading towards the production of coal. It occurs rarely in the British Islands, but is used extensively in Prussia and Austria. It contains when found a large percentage of water, which is difficult to eliminate. It will be seen by Table IV. the extent to which the proportion of oxy- gen decreases in the change from wood to coal — lignite being the intermediate stage.
V. Bituminous Coal. —This is the most important fuel, and presents the varie- ties of splint, caking, open-burning, and cannel coals. These are the coals used for steam, gas, household purposes, and
for iron smelting, in the form of coke or otherwise. The splint and coking coals form the chief produce of the northern counties. Splint is a caking coal with a dull appearance. The open-burning coal also bears the name of " cherry " and " soft coal." The difference between the caking and the open-burning coal is probably due to the larger pro- portion of bitumen in the former, and of oxygen in the lattf r. Cannel coal is most valuable for gas purposes, a maximum proportion of hydrogen, and a minimum proportion of oxygen, being required for this. This coal has probably been ori- ginally formed from the densest vegeta- tion. Its conchoidal fracture, lustreless appearance, and cleanliness to touch, are well known properties. The following is a table, exhibiting the relative quantities of heat given off by the same weight of each of the varieties of bituminous coal, from experiments made by Dr. T. Bich- ardson :
Table III.
|
Species of Coal. |
Locality. |
Relative quantity of heat given out by the same weight of coal. Edinburgh=100.00. |
|
Splint i. |
110.34 115 12 |
|
|
117.83 100.00 116.68 112.12 |
||
|
k |
Newcastle. . |
122.12 114.98 |
VI. Anthracite. — The coals belong- ing to this class are characterized by con- taining a much larger amount of carbon than any other variety, and but very little volatile substance. This coal is generally found in regions distinguished by igneous action, as in Wales and the Alps, and is, probably, bituminous coal, altered by transmittent volcanic heat into a natural coke. In Wales, the same bed may be traced from where it is bituminous to where it is anthracite. The smokeless nature of this coal makes it of great value as a steam coal, there being so lit- tle gas, the setting free of which usually carries off a portion of carbon as smoke, to escape.
VII. Coke. — When coal is freed arti-
VAN NOSTRAND'S ENGINEERING MAGAZINE.
23
ficially from the volatile gases, coke, which -when produced from good coal is nearly pure carbon, is the result. The process of making coke is also resorted to for the purpose of re- moving the sulphur from the coal, and for producing a strong compact fuel for iron smelting. The component parts of several -well-known combustibles are shown in the following table, in which may be observed the chemical decom- position of wood in its gradual conver- sion to coal :
1 able IV.
Carbon
Hydrogen
Oxygen
Nitrogen
Sulphur
Ash
Total
Coke, per cent . .
Specific gravity.
5K) 53
417
20 1000
213 .81
540 52
282 23
6
97
1000
•203 .85
m
M
663, 631 56 89
229, 70
6 2
231 10
23' 198
1000 1000
308 302
1.131.20
801 55 81 21
15
27
1000
604
1.28
849 45 67 10 6 23
*"S
904 33 30 17
16
1000
750
1.28
932
7
9
13
30
1000 1000
921| . . 1.39 ..
It will be seen from the above analyses that the proportion of hydrogen in fuel varies very slightly in passing from one condition to another, whilst the quantity of oxygen is very materially less as the process of coal formation progresses. This is the simple cause of the higher calorific power of coal as compared with wood and peat. The greater portion of the oxygen is set free by natural distil- lation, and hence carbon and hydrogen constitute a large proportion of the resi- due.
The following table (No. V.) shows an analysis of the different coal found in England and elsewhere.
Having now shown the chemical com- position of the chief descriptions of fuel, it will be desirable, for the purpose of illustrating their distinctive value, to com- pare their calorific power, and that of their constituents. This is done in seve- ral ways in the following table (No. VI.), on referring to which it will be seen that hydrogen has by far the highest heating power; hence some coal has more capacity for generating heat than pure carbon. The whole of the hydrogen, however, is not utilized, since, when oxygen exists with hydrogen in any fuel, they form water in the act of combustion, and only the sur- plus is available.
Table V.
|
■a |
|||||||||||
|
Northumberland |
South |
a |
T3 |
||||||||
|
and Durham. |
Wales. |
B |
o a |
a i— i |
S3 |
||||||
|
A |
tu |
^ |
|||||||||
|
V |
<u |
o |
W |
«2£ |
|||||||
|
3 |
o |
S « |
-3 |
2^ |
-3 |
||||||
|
.a . a |
a |
c |
S a a |
2 |
Z$3 T. O |
a o |
si |
o e o |
Q a a |
.5 |
|
|
pa |
02 |
o |
w |
< |
a |
02 |
Hi |
pq |
> |
H |
|
|
Carbon |
843 55 62 21 12 |
787 60 101 24 15 |
868 50 52 10 9 |
807 57 24 13 44 |
923 30 26 6 |
799 48 110 12 7 |
801 65 80 16 14 |
826 59 74 18 8 |
703 54 192 12 |
802 30 48 14 19 |
652 |
|
Hvdrogen |
43 |
||||||||||
|
217 |
|||||||||||
|
N itrogen |
13 |
||||||||||
|
Sulphur |
7 |
||||||||||
|
Ash |
7 |
13 |
11 |
55 |
15 |
24 |
24 |
15 |
32 |
87 |
68 |
|
Total |
1000 |
1000 |
1000 |
1000 |
1000 |
1000 |
1000 |
1000 |
1000 |
1000 |
1000 |
|
750 |
606 |
721 |
751 |
921 |
578 |
549 |
640 |
... |
|||
The difference in value of the several samples of coal is interesting, and seems in favor of the Welsh and Newcastle coal, which are the only coals having a higher heating power than pure carbon. It will be observed that with the exception of
the Derbyshire coal, the calorific power varies with the proportion of carbon. In the case of Derbyshire coal, the oxygen is in such such excess that it absorbs a a large portion of the hydrogen to form water. For the same reason, the heating
u
VAN NOSTRAND'S ENGINEERING MAGAZINE.
Table VI.
|
< |
Composition of Fuel. |
Calorific Power. |
bO |
||||
|
'o'c'S |
* . |
> a |
|||||
|
= = £ |
£<2 |
<y |
|||||
|
«H g |
£ >o |
(=I-J |
|||||
|
J= K2 |
£ — |
V |
|||||
|
O — -U |
O rl |
0 <3 |
|||||
|
111 |
?3^ |
||||||
|
P a c *"-o , ■ 0J o |
|||||||
|
uS*" . |
— t-H |
1* 3 |
|||||
|
a o Q |
a 93 p |
a a> to X |
!h 3 « Ills |
> |
cS O c g • o |
° 2 |
|
|
a |
2 * |
||||||
|
I |
J |
1-1 |
o |
M |
Ph |
i-j |
i-) |
|
1 75 |
00 25 |
62,032 23,513 |
4,265 1,816 |
344.6 146 7 |
62 6 |
||
|
26.7 |
|||||||
|
86 00 |
14 |
21,344 14.544 |
1.466 1,000 |
118.5 80 8 |
21.5 |
||
|
14.7 |
|||||||
|
Carbon burning to carbonic oxide ........ 1 |
00 |
4,453 |
306 |
24.7 |
|||
|
43 |
57 |
3,116 |
214 |
17.3 |
3.1 |
||
|
Coal : |
|||||||
|
838 821 785 795 779 94 GO 50 |
048 053 056 049 053 0004 06 06 |
041 057 097 101 095 007 31 41 |
14,833 14,796 14,150 13,919 13,890 13,197 10,152 8,029 13,500 |
1,020 1,017 973 956 955 900 694 551 929 |
82 4 82.2 78.6 77.3 77 2 72 7 56 4 44.5 75 0 |
15 0 |
|
|
14.9 |
|||||||
|
" Scotch |
14.3 |
||||||
|
14.1 |
|||||||
|
14.0 |
|||||||
|
Coke |
13.2 |
||||||
|
10.3 |
|||||||
|
Wood, drv |
8 1 |
||||||
|
13.66 |
|||||||
|
•• |
13,208 12,931 4,032 |
909 889 277 |
73 2 71.8 22.4 |
13.4 |
|||
|
13 1 |
|||||||
|
4.1 |
|||||||
power of coke is less than that of coal, owing- to so large a proportion of hydro- gen being driven off in the manufacture of the coke. The heating power of marsh gas, or light carburetted hydrogen, may be said to present an unfair comparison with coal, since the heating power of 1 lb. of coal will be considerably greater than the power of the gas produced from it by distillation. This also applies to coke. One pound of coal having a heating power of 14,796, when made into coke, would have a power, supposing the pro- duction of coke to be 60 per cent., of only 13,197 X -60= 7,918.
The presence of oxygen in fuel acts in a twofold manner in reducing the calorific power, by reducing the actual amount of carbon and hydrogen, and by rendering part of that amount ineffective for gene- rating heat.
Hydrogen in fuel is only useful for the development of heat, when the propor- tion of it contained in any combustible is in excess of -^ of the quantity of oxygen con- tained in the same combustible.
A New Atlantic Steamer. — One of the largest Atlantic steamers ever built has been floated from the shipbuilding yard of Messrs. Laird Brothers, Birken- head. The vessel has been named the Spain, and is to form one of the National Steamship Company's line between Liver- pool and New York. Her length is 437 ft., her breadth of beam 43 ft., she is of 4,900 tons burthen, and has accommoda- tion for 1,200 first-class and 1,400 steer- age passengers. The engines of the Spain are stated to be the largest ever con- structed on the compound principle, and the vessel is expected to have great speed both under steam and canvas.
The General Post-office of Great Britain has decided to at once extend tele- graphic communication to Stornoway, in the Western Hebrides. The submarine cable to be laid across the Minch will be some 28 nautical miles in length, and sub- merged in water of the average depth of 50 fathoms.
VAN NOSTKAND'S ENGINEEKING MAGAZINE.
25
ON COMPLETING THE LAUNCHING OF SHIPS WHICH HAVE STOPPED ON THEIR LAUNCHING SLIPS.
By WILLIAM BRAHAM ROBINSON, Esq. From the "Journal of the Society of Arts."
The Caesar, a 90-gun two-decked wood- en ship, having been prepared for launch- ing, was attempted to be launched on the 21st July, 1853, at the Royal dockyard, at Pembroke dock , but after she had slid down the launching ways some '80 ft., and thus immersed her after-part into the water at high tide, she stopped entirely,* and all the subsequent efforts made that day to move her were of no avail. The declivity given to the launching-slip was the usual amount, and the plank and ma- terial used in the ways were also of the usual description. The plank on the launching-slip was pitch pine, a material commonly applied to that purpose at Chatham-yard, though it had not been used at Pembroke for some years previ- ous in launching heavy ships.
Between the 21st and 26th July, some small hollow vessels, built for the pur- pose, and a few casks, etc., were put un- der the ship's bottom, below high-water mark, with the view of reducing the weight of the ship on the ways, and at the time of high tide efforts were then made, by means of purchases, to pull the ship off, but all these measures were un- availing.
A careful inspection of the work at low water the night after the ship stopped, and on subsequent occasions, convinced me that the real cause of the failure on the 21st July was the want of a sufficient and proper lubricant between the sole of the ways and the launching-slip, and the sliding surfaces being made too smooth by planing them. Acting on this opinion, and observing that the ship's stern was sufficiently immersed in the water, when the tide was up, to admit of proper ves- sels being placed so as to lift the ship abaft, I advocated persistently before the then master-shipwright the necessity of adopting the unique plan of building camels for breaking the too close contact that appeared to be established between the sliding-ways and the launching-slip, by lifting the stern of the ship so as to take its weight off the launching-slip. On
* I was not the responsible officer engaged on the launch.
Tuesday evening, the 25th July, it was determined to build 3 large camels for this purpose. I thereupon caused to be laid off in the mould-loft, in a few hours, a camel to fit each buttock, 72 ft. long, to be planked with 4-in. fir plank, and one for the stern 20 ft. sq. in section, and 48 ft. long to be built of 5-in. fir plank, the collective lifting power, when properly in place, being estimated equal to 1,100 tons. The artificers were set to work from 3 a.m. to 8 p.m. cutting out plank, etc., for these camels, no suitable material being in the yard, and in the incredibly short period of 9 days these large ves- sels were built and launched, and on the following day, the 5th August, they were got partly into place, under the very great difficulty of having to secure the after one with nothing firmer to rest upon than soft mud. On two subsequent tides, the camels being only imperfectly shored down, and therefore only partially in ac- tion, the ship was moved, when a pulling power was applied, 9 ft. and 45 ft. suc- cessively ; and at last, on the evening tide of the 17th day after the ship had stopped on the slip, the camels having been prop- erly kept down in their places by bear- ers put out at the quarter-ports on the lower deck, and shored to the main deck upper sills to keep in place the quarter camels, a similar plan having also been adopted to keep down the stern camel, without any pulling power being applied, the ship, about one and three- quarter hours before high-water, aban- doned her unworthy connection with the land, and glided gracefully into the haven, amidst the rejoicings of all the people in Pembroke dock. An examination of the launching-slip after the ship had left it, proved that the opinion I had formed had been founded on no hypothetical reason- ing, since the absence of grease was ap- parent enough, and the too great smooth- ness of the sliding surfaces was equally evident. The camels, it may be added, which have been briefly described, were provided with valves for reducing their lifting power, but it was not found neces- sary to use them.
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During the 17 days and nights the ship remained on her slip, it -was pleasing to observe the interest every man in the yard appeared to feel in the preparations making to get her off ; and they worked most willingly day and night, the water drinkers coming out of the trial fresher certainly than many others.
On the 9th August the ship was docked, the stern camel having been kept in place, and 70 tons of ballast having been put on board forward to trim the ship. The sheer of the ship, which had broken when the ship was on the launching-slip about 1 6", returned in great part to its normal form on docking the ship, and it was held there by the introduction of "double fastenings " in the wales, and by an ad- mirable method of coaking and " keying up " the iron diagonal riders proposed by the then master-shipwright of Devonport yard.
With the experience of the case of the Csesar stamped on my memory, I survey- ed the condition of the Northumberland when she stopped on her launching-slip on the 17th March, 1866, as the Csesar had done, and I at once observed that her position was just such as would re- quire her to be dealt with in the same way as the Csesar had been — with this difference, that in the case of the former ship, a very rigid iron hull, which would keep the ways straight and to their form, had to be dealt with, instead of, as in the case of the Csesar, a flexible body, which would bend, if not well supported, to a large extent before breaking.
On the afternoon of the day on which the Northumberland stopped on her launching-slip (the 17th March, 1866), after I had carefully examined into all the circumstances connected with the position the ship was in, I inquired for the office, and obtained after some trouble a quarter of a sheet of foolscap paper, upon which I briefly described the experience I had ac- quired in the case of the Csesar, and pro- posed lifting the ship abaft by means of camels built for the purpose, or suitable small ships which might be found lying in the river ; and this definite proposal I put into the hands of Mr. Lungley, the then manager of the company, when that gentleman was standing alongside the ship.
On a subsequent day I mentioned the
subject of the memorandums referred to, to the chairman of the company, but not- withstanding this, nearly the first action taken was to lay a second launching-slip alongside the original one, at a less de- clivity than the original slip had been laid at. This was done I believe with the view of sliding the ship down far enough for her weight to come upon the slip with the lesser declivity. Together with this certainly very novel arrangement, some means for lifting the ship abaft by moor- ing lighters, etc., was provided ; and on the 2d of April, all being ready, an attempt was made to complete the launch of the ship; but it failed, as I had predicted it would when speaking to the gallant chair- man of the company at the head of the ship, just before the event.
Immediately after this failure my pro- posed plan of lifting the after-part of the ship was adopted, and measures were taken to build the requisite camels in the two neighboring Royal dockyards, Woolwich and Deptford, where the usual willing exertions were exhibited by officers and men ; and the four camels — two for each quarter — were built in a very few days ; and they were secured in place by the 17th April (just one month from the first attempt to launch the ship being made), and on the rising of the tide they lifted the ship abaft off the launching- slip, when she glided into the river with- out the help of the large pulling power which had been provided.
The camels which have been referred to were admirably detailed by the officers who built and prepared them, and the valves were most successfully managed on the day of the final launch, so as to pre- vent the camels from lifting the ship above the ribands on the launching-slip.
The day after the ship left her launch- ing-slip, I, at low water, inspected the slip, the plank of which was oak, not fir, as in the case of the Csesar, and saw enough to convince me that my first im- pression had been a right one, namely, that the ship had stopped in the first in- stance mainly for the want of a proper and sufficient unguent on the ways and slip.
The forces in action when a ship's stern is lifted under similar circumstances to those which obtained when camels were used to lift the after-parts of the Csesar and Northumberland may be illustrated
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as follows, by which it will be seen that it could scarcely be necessary to provide a
large pulling power in addition to the lifting power of camels : —
Fig. A, represents a ship in the posi- tion I have been describing, and it will be seen that the forces acting upon her are as follows : —
1st. Weight, W, acting downward through the centre of gravity of the ship.
2d. The upward thrust, P1,of the ca- mels, which is equal to their buoyancy, and acts through the common centre of gravity of their displaced volume.
3d. The re-action, P, at the fore end of the slipway.
The force which acts to push the vessel down the slipway, we will call F, and this will be equal in amount to —
P sine L -/iP, cos L = P (sine L— n cos L).
When fi is the coefficient of friction, and depends upon the kind of unguent used, and L is the angle of inclination of the sliding plank.
By reference to the figure it will be seen that —
P = w
and as a will under most circumstances be nearly equal to au we may take —
W
2
P =
and we shall then have —
W
F = — — (sine L— n cos L).
a
If the stern of the ship were not lifted, but her whole weight rested on the slip- way, the force acting to push her down the slip would be —
W (sin L — 11 cos L).
or double what it is in the present case.
The advantages obtained by the use of camels are due to the fact that they take all the weight of the ship off the bilge-
ways, except at the extreme fore-end, so that the after-part is lifted clear of any obstruction that may exist ; or, where the grease used is bad or insufficient in quantity, the adhesion of the surfaces in contact is overcome, and they are left free to slide upon each other.
To the foregoing it may be added that due consideration should at all times be given in preparing the " launch" of a ship to the relative weight of the ship and area of the soles of the ways, declivity of launching-slip, and to the time it is in- tended the ship shall rest in her cradle before the launch takes place, and then finally on the kind and quantity of grease to be used between the sliding surfaces. All these points affect the stiction to be overcome in launching the ship.
Origin of Graphite. — Prof. Wagner as- cribes the deposits of graphite, plum- bago, or black lead, which are found in a great variety of rocks of different geologi- cal periods, to the decomposition of cyano- gen, which is a combination of carbon and nitrogen, or of the cyanides. In several chemical processes used iu the arts, graphite is formed artificially; and it is not impossible that this expensive mineral, the best specimens of which are now brought from the island of Ceylon, may be produced artificially in such quan- tities as to be made available in several branches of manufactures where this mineral is indispensable. Chemists, how- ever, have not yet accepted Prof. Wagner's explanation, or any other, as to the natu- ral production of graphite. — Iron Age.
L
ondon is now in direct telegraphic communication with Hong Kong.
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THE MAKING AND EEPAIPJNG OF EOADS.
From "TUo BuiMiug News."
A road should be considered as a struc- ture having two essential parts, a founda- tion and a wearing surface. The duty of the first is to keep up the second to its work, and may be made in any way that satisfies the one condition of unyielding firmness. It has been sometimes said that a slightly yielding or elastic founda- tion is better than a rigid one; and if that elasticity could be had at a sufficient depth below the surface it might be so, but prac- tically it is not to be had, and the danger of trying to make the foundation elastic far exceeds the objection of rigidity.
A great deal of unnecessary discussion used to be indulged in as to whether the plan of making the foundation which was adopted by Mr. Telford or that practised by Mr. Macadam was the better. Telford's plan was to pitch the road-bed with rough stones, set closely by hand, with their broadest edges downwards, and then- greatest length crosswise of the road, the breadth of the upper edge of any stone not exceeding 4 in. All the irregularities of the upper part of the pavement were broken off by the hammer, and the chips packed by hand and wedged into the in- terstices. The depth of the stones when finished off was 7 in. in the middle part of the road, 5 in. at a distance of 9 ft. on each side of the centre, 4 in. at 12 ft., and 3 in. at 15 ft. The surface thus formed a curve, having a rise of 4 in. in the centre. This is clearly a good foundation, but it is somewhat against it that the bed is flat, and that if water should percolate through the top coating and through the pave- ment it would, on some kinds of ground, as upon clay, weaken its bearing power ; but if the ground is porous, as sand or gravel, or rocky, as it was on most parts of the great Holyhead road made by Mr. Telford, this objection to a flat bed does not arise. Whenever the bed, however, consists of clay or other impervious ground, the bed should be sloped down- wards from the centre to the sides to about the same extent as Mr. Telford allowed — viz., 4 in. in a width of 15 ft., so that water may drain away. Two straight slopes for this purpose are better than a curve. Macadam, on the other hand, considered this pavement foundation to be
unnecessary, and insisted that the native soil, properly formed and drained, must be considered to be the foundation, and carry the weight of the traffic ; and that whatever stone may be laid on is only to preserve this foundation from injury, and its thickness should be regulated only by the quantity of material necessary to form such a protection, and not at all by any consideration as to its own independent power of bearing weight ; and that it is an erroneous idea that the evils of an un- drained, wet, clayey soil can be remedied by a large quantity of materials.
But what makes the discussion upon the two methods of little use, is the fact that Macadam's own practice approaches that of Telford, for on laying on the bro- ken stone he was careful to lay first a layer 3 in. thick, and have that pretty well consolidated by traffic before any more was put on ; and this and the succeeding layer may be 'taken to stand in the place of the pavement of Telford. The native surface having been formed, Macadam's system was to lay first a layer of 3 in. of clean broken stone on a dry day, and after the traffic had almost, but not quite, consolidated it, the ruts being kept rake^d in as soon as they are formed, a second layer of 3 in. was laid down in a wet time, moisture facilitating the union of the two.
Then the third layer forms the top coat, and carries the traffic. Macadam insisted strongly on the necessity of the stones be- ing clean and angular, whereby the angles interlock with each other and form a solid structure ; whereas, if other material be admitted under the pretence of binding, it prevents this close union, absorbs water, and in frost disrupts the mass. Mac- adam's method of laying the foundation — that is, the first two layers of broken stone — has the disadvantage that in wet clayey ground the traffic forces the stones into the ground, and it rises through the in- terstices, although Macadam maintained that draining would prevent this. Drain- ing, however, cannot altogether prevent it, and it is only to be prevented by select- ing a dry time for laying down the first layer of stone. The first layer being ac- complished, the second becomes easy. Telford's pavement is easy under any
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circumstances and in any weather, but is more expensive. It has the advantage, however, of distributing the weight on the surface over a large area of foundation, for if we take a wheel touching 2 sq. in. of the surface, the pressure is carried down to the foundation stones, which rests on a broad surface of, say, 10 in. by 5 in., or 50 sq. in., so that the bearing surface is multiplied 25 times. To pre- vent the displacement of the foundation stones, the carts bringing the stone were not allowed to pass over them.
The foundation, then, having been laid, whether of one or the other kind, or in any other way, so that it be unyielding (in the manufacturing districts engine ashes are largely used, and make a very good foundation, laid on 7 in. deep in two lay- ers, the traffic being allowed to pass over them before the top coat is put on), the wearing coat has then to be put on, and now the quality of the stone comes into question. The most durable stone is that which is toughest. Mere hardness is no test of quality for the purpose of road making. Flint is hard enough, but it is almost the worst material for a road, because it has no toughness.
In his " Discourse on the Study of Nat- ural Philosophy," Sir John Herschel says: — " Hardness is that disposition of a solid which renders it difficult to displace its parts among themselves ; thus steel is harder than iron. The toughness of a solid, or that quality by which it will endure heavy blows without breaking, is again distinct from hardness, though often con- founded with it. It consists in a certain yielding of parts, with a powerful general cohesion, and is compatible with various degrees of elasticity."
The most useful stone is that which is most difficult to break up. Such is the blue granite of Guernsey ; a trap rock found at Clee Hill, in Shropshire (the Clee Hill Dhu stone) ; a stone got near Macclesfield, in Cheshire ; the whinstone of the north of England ; the Penman- maur stone from "Wales ; beach pebbles and boulders ; a stone brought in the bottoms of ships as ballast from Bombay ; another from Port Philip ; and other sucb kinds of stone. Stone of secondary quali- ty is the carboniferous or mountain lime- stone, and the harder sandstones. Broken flints form a third quality, and the lowest is flint gravel. This last is unfit for any-
thing but by-roads. It is very extensively used in the south of England for all kinds of roads, but it is not economical to use it where there is considerable traffic. The comparison of the strength of different kinds of stone by the steady weight that pieces will bear before crushing is not admissible in the case of road-stone, for the weight it has to bear is not a steady one, but one of impact. Most of the roads round London are made with flint gravel, and in the coaching days there was a select committee of the House of Commons upon highways, and before that commit- tee evidence was given that for the first few stages out of London it required ten horses to do the same work that eight did beyond them, and that the horses out of London, although better animals to begin with, were worn out in four years, while on other roads they would last six years. It may be laid down as an axiom that it is more economical to bring good materials from a distance than to use inferior ones obtained close at hand. Thus, in London, for the heaviest traffic it is more econo- mical to use Clee Hill Dhu stone at 16s. 3d. per ton, Enderby stone at 15s. 6d., and Guernsey granite at 15s. 6d., than any other stone, although the prices are less ; and at Manchester they use the Penmanmaur stone at 12s. per cubic yard rather than other stone which might be had much nearer. The thickness of this top coat is not of much consequence ; it is only required to protect the foundation from the action of the traffic ; and may be any thickness that is convenient ; and the most economical thickness will be de- termined by considerations of labor — how much it costs to lay down a coat of 2 in., one of 3 in., one of 4 in., and if 6 in. be put on it must be put on in two layers of 3 in. each, and then how much will that cost ? And each of these costs must be compared with the standard of wear, which will be the same whatever thickness the coat of stone may be ; and in this, as in many other things, the middle course will more often be right than either extreme, and it will generally be found that from 3 to 4 in. is the best thickness. It is true that on such a foundation as Telford's more than this is required above the pavement, or the road would be too rigid ; and accordingly Telford directed that 4 in. of broken stone should intervene between the pavement and the top coat of stone.
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" The middle 18 ft. of pavement is to be coated with hard stones to the depth of 6 in. ; 4 in. out of these 6 in. are to be first put on and worked in by carriages and horses, care being taken to rake in the ruts until the surface becomes firm and consolidated, after which the remain- ing 2 in. are to be put on." The next thing to be considered is the size to which the stone of the top coat shall be broken. Both Telford and Macadam said, to such a size that its longest dimensions should be not more than 2| in., which would be, for average materials, cubes of about 1| in., and Macadam further directed that no stone should be more than 6 oz. in weight. But neither dimension nor weight can be accepted as logically defining the proper size, because that depends upon the na- ture of the material. To reduce flint or sandstone to the dimensions proper for traprock and granite, would be to insure their immediate grinding up and removal from the road. But there is no doubt that for the better kinds of stone the size can hardly be too small, so long as they are broken to a uniform size, and here the superiority of hand-broken stone over that broken by machine is very evident. Hand-broken stone is more uniform in size.and approaches mare nearly to the best form — the cube — than can be had with any machine, for while the machine breaks up some of the stone into too small frag- ments, it cracks many of the pieces of the right size, and thus when the traffic comes over them they split, and they are split also by the action of frost. We believe the French engineers disregard the clean- liness and uniform size insisted upon by Macadam, and allow even dust to be mixed with the clean angular stone, but we are convinced that this is a mistake. The object of having the stones clean and free frorn extraneous matter, is that they shall interlock, and the angles adjust themselves so as to come home, stone to stone, and so form a solid body ; but when dust or other substance is allowed to come into the cavities they cannot do so, and are thereby rendered less stable. It is probable that the success of the French engineers in making roads is due to the attention they pay to rolling the surface ; but even by that means they cannot force the stones into contact when dust intervenes. Breaking stone would seem to be a simple thing enough, and
i one that any able bodied-man may do as I well as another, but it is not so. In the first place, it requires a particular kind of hammer. The head must be of solid steel. The shape of the face of it must vary with the kind of stone to be broken. The handle must be pliable, and not a stiff piece of wood — it must therefore be a green stick — and hazel or ash plant is used. Then a stone-breaker must know where to hit the lump he is to break, and where he shall hit it depends on the na- ture of the stone. A great deal of strength is wasted by men unaccustomed to stone- breaking, who take up the work for the first time, and work with tools of the wrong kind.
The shape of the surface of a road is important. There are three forms of sur- face ; one, the most common one, a curved surface, having a rise from the water channel to the crown of 4 in. or 6 in. ; the second form is the straight slope on either side of the centre ; and the third the hanging road, where the slope is all to one side, the road having only one water channel. In the latter case it is generally dictated by local circumstances, but the other cases are general. The higher the crown is made above the water channels for the sake of getting the water quickly off the road, the more is the traffic restricted to the centre of the road, for nobody will drive on sidelong ground if he can get a level footing. There is not much differ- ence between the two forms, for if the road be made at first with straight slopes it will soon become worn down at the apex into something like a curved form . But there is a good deal to be said against the practice of raising the centre of the road too much in either way, for the ob- ject ought to be to get the traffic spread equally over the width of the road, and thus we come to the conclusion that as little rise as possible should be given to the crown ; and 3 in. in 10 ft., or 1 in 40, is sufficient to allow the water to run off, and if it takes a longer time to run off such a road than it does on a more round- ed one, that is of less consequence than unequal wear.
The road having been formed, it has to be maintained as nearly as possible in its original form, There is no stone that is of exactly a quality throughout, and the reason why a road wears into holes is that the softer parts here and there are
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worn away before the rest, leaving the hardest portions of the stone standing up in ridges or knobs, and when this attains to a sufficiently objectionable degree the holes are to be filled up with new stone broken very small, and no more stone used than is sufficient to bring the surface up to the level of the adjoining unworn portions of the road.
The common error is to put too much stone on a place that wants some mend- ing, and many roads have been raised considerably above their original level. The object should be to keep up the thick- ness of the metalling as nearly as possible to that it originally had. This cannot be done absolutely, but it can be approxi- mated to ; for instance, if the original thickness of the top coat be 4 in., 1 in. of the best part of the material, as well as that used for patching, will be worn away in, say, twelve months, leaving the thick- ness no where more than 3 in. It will be proper then to repair the road with a fresh coat of stone, raising the thickness to, say, 5 in., which would then allow two years' wear before another coat of stone would be required.
Whenever a new coat may be necessary, the surface of the road is to be picked up to a depth of 2 in., the surface readjusted in form, the material sifted and relaid, with the addition of as much new stone as may be required to make up the 2 in. The time of year most suitable for repair-
ing roads is the spring ; the succeeding slimmer then hardens the road and leaves it in a good condition to resist the traffic during the wet winter months.
Of the new asphalt roadway, the Eng- lish experience is not yet sufficient to enable xis to judge of its durability; but so far as it has gone the wear appears to be absolutely nothing in Threadneedle street and Cheapside, and the smoothness and noiselessness are much in its favor ; but although it may ultimately be generally used, stone paving will probably continue in use for many years for the heaviest traffic, although the objections to it, even to the best kinds of stone, are numerous, and some kinds of stone are simply abominable from their slipperiness ; and the noise that a stone-paved road pro- duces is such that where the residents have sufficient influence over the parish or other local authorities, they prevent it being laid down, and in other instances, where the appeals against it have been unsuccessful, residents have vacated their houses, and the authorities have lost the rates upon the property. The only thing that can be said for stone paving is that it costs less in maintenance than a macada- mized road does, where the traffic is ex- cessively heavy ; but when we come to get broken stone properly rolled and set before the traffic is turned on to it, there will be some hope of the more extensive use of that kind of road.
THE MINEKAL WEALTH LOST TO FKANCE.
From " The Mining Journal.'
Commissaries have been charged by Germany with the task of definitively ad- justing at Brussels the conditions of the treaty of peace between France and Ger- many, and the German officials comprise a gentleman associated with mines. It is inferred from this circumstance that Ger- many is aiming at an industrial prepon- derance in Europe as well as at a consoli- dation of its military power. This policy will, probably, be attended with important consequences, not only for France and Germany, but also indirectly for Belgium and England. In consequence of the mineral wealth of the departments in the east of France, the French iron trade gradually acquired considerably increased
importance during the 15 years ending with 1870 inclusive, although since last July it has, of course, been greatly de- pressed by the course of public events. In 1850 the total production of pig in the French furnaces amounted to 500,000 tons, of which about half was made with char- coal. The production had risen, however, in 1867, to 1,222,303 tons, and in 1808 to 1,274,333 tons, less than one-fifth being made with charcoal. Exact returns for 1869 and 1870 have not yet been made up by the French Government, but the pro- duction for 1869 has been estimated by the French Committee of Forgem asters at 1,380,000 tons, so that the production of pig in France would seem to have nearly
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doubled within the last 20 years. In 1867, out of the whole total of 1,222,303 tons of pig made, the department of the Moselle produced 281,045 tons, or about one-fourth of the whole, and it is proba- ble— although precise statistics on the subject make default — that considerable further progress was made in the Moselle during 1868 and 1869, as of all the French metallurgical groups it has generally dis- played the greatest activity.
It is upon this fine district that Ger- many has this year laid its hands, in con- sequence of the collapse of the military power of France before the terrible le- gions of Prince Bismarck and Count Von Moltke. Through the new delimitation of her frontiers the Longwy basin has alone remained to France; and taking the statistics of 1867 as our guide, it would seem that the delimitation will be attend- ed with the following results :
Work remaining in France.
Production. Establishment. Furnaces. Tons.
Gorcv 3 5,457
Mont St. Martin 2 19,425
Longwy Bas... 2 8,542
LePrieure 2 „ 15,447
Moulaine 2 10,905
Senelle 1 4,200
Rehon 2 12,490
Total.
12 76,466
The following will be transferred to Ger- many:—
Works in Alsace and Loraine.
Production.
Establishment. Furnaces. Tons.
Styring-Wendel 3 45, 943
Hayange 5 50,563
Moveu vre - . . . . 3 37, 044
St.'Paul St. Benoit Ars .. 4 27,540
Ars-sur-Moselle 1 9,070
Ottange 3 13,928
St. Claire 1 2,389
Mauterhausen 1 2,445
Noveaut 1 12,324
Villerupt..... 2 2,233
Audun-le-Tiche 1 1,100
Total .
25 204,579
Three-fourths of the production of the old department of the Moselle will thus be diverted into the Zollverein, and the works ceded from the power of their capital, the force of their tools, and the extreme rich- ness of the mineral bearings conceded to them, represent more than the proportion- ate share which they sustained in the total production.
It would appear that the Prussian plenipotentiaries have traced out the new
frontier, not on any topographical plan, but very probably on a geological map prepared at Berlin. It is noticeable, for instance, that the new limits between France and Germany absorb, to the profit of the Germanic Confederation, all the rich bearings of oolitic ironstone in the Moselle and the Meurthe, the Longwy group excepted. Thus the concessions remaining in France comprise an area of 5,336 acres, producing, according to the last available return, 140,281 tons per an- num, while the concessions in Alsace and Lorraine tranferred to Germany comprise an area of 18,062 acres, with a production of 500,660 tons per annum. The "Moniteur des Interets Materiels" considers that the relative production of pig in various European countries will be rather pro- foundly modified by these changes, and compares as follows the production of pig in 1866 with the estimated production of 1872:
Production, 1866. Production, 1872.
Country. Tons. Tons.
Great Britain 4,592,000 5.100,000
France 1,253.000 1,062,000
Zollverein 1,079,000 1,907,000
Belgium 421,000 526,000
Austria 292,000 365,000
Sweden 236,000 293,000
Russia 350,000 420,000
Other countries... 90,000 100,000
Total 8,313,000 9,7^3,000
The proportion sustained by Great Britain in the total production will, ac- cording to this estimate — which, after all, is rather curious than reliable — thus fall from 55 per cent, in 1866 to 52 per cent, in 1872. That of France will also fall from 15 to 11 per cent., but that of the Zollverein will advance from 13 to 19 per cent.
Titanic Ore. — At the last meeting of the metal and coal trades at Swansea, a sample of titanic ore was exhibited con- taining a very large percentage of titanium. The price of the ore was 25s. per ton ex- ship in the Bristol Channel. An analysis of this ore yielded the annexed results: Iron, 40.88 per cent.; oxygen, 20.57 per cent.; titanic acid, 31.72 per cent.; silica, 3.17 per cent.; lime, 0.97 percent.; mag- nesia, 1.00 per cent., etc.
I^he State with the greatest railroad mile- . age is Illinois, which has 7,186 miles.
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CALCULATIONS OF STRAINS IN TRUSSES.— NO. III.
A reference to the calculations in the last article shows that the method applies to the diagonal and vertical members of a truss, because these take the greatest strain when the girder is partially loaded. To determine the law of depend-
ence of strains upon the distribution of the load, it is only necessary to consider the general equations of moments, and to represent by diagram the girder in the condition corresponding to the omission of positive or negative members. It is thus
Fig. 1.
seen that any diagonal as Y3 in the third bay receives a maximum tension if all apices at the right are loaded; and a maxi- mum compression if all points at the left are loaded. If, in the same bay, instead of a diagonal sloping to the left, one slop- ing to the right be substituted, the reverse would be the case. For, if the girder is viewed from behind, the diagonal Y6 ap- pears in a corresponding position, and the equations of moments would also corre- spond.
If both diagonals appear, and are con- structed as ties or tension-members, not capable of compression, each is brought into action only by a distribution of load that causes tension, while the other is in the condition of a cord just stretched without strain. In this case only the maximum valves of Y enter; e. g., in the third bay, for the diagonal Y3 (max.) and for the diagonal Y6 (max.). In a similar manner the strains of all diagonals can be found.
For vertical members of such a girder only the minima of the valves for V are taken into account, because tension cannot occur in them, if each of the diagonals meeting at a vertical is incapable of re- ceiving compression.
A glance at Fig. 2 shows that this is impossible, otherwise the vertical force V would be taken up by no opposing force. That these minima apply to a girder with intersecting or crossing diagonals appears
from the consideration that for a load on one side, only one of the two systems of diagonals is strained, so that the other need not be taken into account.
Hence with the results obtained, as in the last article, the magnitudes of the greatest tensions may be written on the corresponding diagonals. Fig. 2.
/v
If the diagonal members are constructed so as to receive compressions, as in the case of wooden trusses, an entirely similar process is adequate to obtain the desired results; but only the minima for diagonals and the maxima for verticals remain the same. As to the minima, it is plain that if the diagonals cannot convey tension, the direct load is the only one that can cause compression in the verticals. This varies (in the case of the last article modi- fied for this occasion) between 1,000 and 1,000 -f 5,000; hence
V(min.)= -6,000 k.
The strains from left to right are as follows (for loads as in last article, for truss with intersecting or isosceles diago- nals) :
|
Bayl. |
2. |
3. |
4. |
5. |
|
|
— 48,000 + 52,500 — 6,000 |
— 48,000 + 50,300 — 6,000 — 6,250 — 5,470 |
— 48,000 + 48,900 — 6,000 — 6,850 — 6,250 |
— 48,000 + 48,100 — 6,000 — 7,080 — 6,850 |
— 48,000 |
|
|
Lower chord |
+ 48,000 — 6,000 |
||||
|
Verticals |
|||||
|
Diagonals sloping to left ... |
— 6,850 — 7,080 |
Vol. V.— No. 1.— 3
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In case of diagonals sloping only from the centre towards the abutments, the tension depends exclusively upon that of the chord segments intersecting at the foot of each. These are always subject to tension and therefore can only cause com-
pression in the verticals. This is a maxi- mum for a full load.
If the diagonals slope only from the abutment towards the centre, the direct load alone causes a strain in the vertical members.
IEON ABUTMENTS.
From "The Engineer.
Although there are abundance of in- stances in which iron, both cast and wrought, is the material used for the piers or intermediate supports of bridges, the examples are comparatively rare in which it is also employed for the terminal supports or abutments. It might appear, at first sight, that if the nature of the foundations rendered it advisable to adopt iron in the piers, the same con- ditions would dictate the use of iron in the abutments. But there are many reasons which demonstrate that this view is not necessarily correct or conclusive. In the first place, the character of the substratum in a tolerably wide river, often differs at different parts of the transverse section, and it is seldom that both abut- ments are founded at exactly the same level. There is a notable difference in the nature of the ground on the Surrey and Middlesex shores of the Thames, for ex- ample, and a dam that would fully answer its purpose on the one might not always be sufficiently strong on the other. This fact was well shown during the construc- tion of that portion of the Northern Embankment near Blackfriars Bridge. Our readers will probably remember that a serious "blow" occurred in the dam, and yet this dam was almost identically similar in design to that which did its duty so well during the building of the river wall from Westminster to Vauxhall on the Surrey side of the Thames. On geological groxxnds, therefore, alone, brickwork or masonry might be well adapted for the abutments of a bridge, and yet be superseded by iron, with ad- vantage, in the more central and deeper parts of the stream. It is not, however, until we come to regard the different duties a pier and an abutment have to perform, which necessitate a diversity in constructive detail, that the real reason of the general unsuitability of iron for abut-
ments becomes manifest. The sole duty that a pier has to perform, so far as relates to the actual bridge itself, is to bear the direct vertical pressure of so much of the superstructure as falls to its share. There a^e no doubt in many in- stances other forces in operation which try its stability and strength, such as the velocity of a marine or river current, the impact of ice, or the concussions of floating bodies, but these are beside our subject. It is otherwise with an abutment. In addition to bearing its own share of the direct weight of the superstructure, it has to act as a retaining wall. It will be understood that at present we are speaking of those forms of bridges which exert no thrust against either the piers or abutments. As every bridge must have an approach to it, which is most fre- quently of earth, it is the necessity of making the abutment support this, that gives masonry or brickwork a decided superiority over both cast and wrought iron. Neglecting the value of the limit- ing angle of friction of the material, the horizontal pressure against the abutment will be directly proportional to the sheer mass or weight to be resisted, and com- mon sense woidd instruct us that in all similar cases weight is best resisted by weight and solidity.
So far we have only taken into con- sideration that portion of the end sup- ports which may be termed the abutments proper, but this is seldom sufficient of itself to retain the whole cross section of the approach. The retaining wall, re- garded as a whole, comprises not merely the central vertical part which carries the superstructure, but the side portions as well, which have no vertical load to sup- port, and are known as the wings of the bridges. These may be either " straight back" that is, built in a line parallel feto the direction of the bridge, or "splayed,"
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that is, receding from the face of the abutment at any given angle. In the former instance the top of the wing wall is horizontal, and in the latter, which is the forni under present notice, the height diminishes from a maximum at its junc- tion with the abutment to a minimum at the newel, the slope being parallel to that of the embanked approach. It is in the wings that the chief difficulty of employ- ing iron with economy would be met. In the abutment proper a certain degree of strength is required to carry the vertical load, and this amount can be simultane- ously utilized as a contribution to the total necessary for the retaining wall. On the other hand, the wings act simply as re- taining walls, having no vertical weight to bear, and the question becomes reduced to one involving the relative economy of iron and masonry or brickwork. With- out desiring for a moment to place a limit to the skill and ingenuity of engineers, yet we hold that for certain purposes cer- tain materials are more suitable than others, and that the substitution of the wrong for the right is only effected at a commensurate sacrifice on the score of economy. Except in examples such as armor plating, targets, and engineering works of a warlike character, the substi- tution of iron for the older materials used in construction, will generally be found to be nearly equivalent to the substitution of the hollow for the solid form. Take the earliest, the cast-iron flanged girder. It is nothing else in form than a beam with the material cut away about the centre. The same statement holds good for wrought-iron girders, and the hollow column is only the stone pillar with its core extracted. It is not difficult to under- stand that a given amount of metal which would be able to support a given vertical weight would be quite inadequate to resist the same weight acting in a horizontal direction, or at an angle with the horizon. In the one case, supposing that there was no bending moment induced, the iron would only yield to a weight equal to its crushing pressure; in the other the resist- ance it would give would depend upon the direction of the strain it was subjected to. Iron wing walls must evidently con- sist of plates which, per se, have little or no stability, and this feature can only be imparted to them by the addition of stays and bracing. Some years ago we ex-
pressed our views on this very subject, and shall not recapitulate them, though we may observe that we have since seen no reason to alter our opinions.
Our attention has been again drawn to this question by a paper lately read be- fore the Institution of Civil Engineers, " On the New Ross Bridge." In this case the abutments and wing walls consisted of cast-iron cylinders with cast-iron plates fitting in between them, and a strong backing of concrete, which is tan- tamount to so much solid masonry. The design of the cylinders and plates is pre- cisely analogous to that constituting the foundations of the piers of Westminster Bridge, if we substitute piles for cylin- ders, and is nothing else than a cast-iron frame and panelling. The relative econ- omy of this method of construction de- pends wholly upon the difficulties that may result from the presence of water. To build a retaining wall on dry land of cast-iron framing and panelling, to sup- port a 25-ft. embankment, would be simply a great and unjustifiable waste of money ; but to employ the same design in 25 ft. depth of water is another matter altogether. As a rule, it is certainly more expeditious to sink cylinders under water, and drive down panel plates be- tween them, than to construct a tempor- ary dam and build a solid wall of mason- ry and brickwork behind it. But it is not always so. If it can be satisfactorily established before the commencement of the work, that, from the nature of the substratum, there will be no trouble with the water, it is more than probable that the temporary dam and the solid wall would come quite as cheap as the cylin- ders and panelling. It is true that the latter plan dispenses with the temporary dam, but the sinking of the cylinders is not all plain sailing. It must also be borne in mind that, wherever cylinders are easily got down, it is equally easy to drive timber piles and construct a dam. Omitting the contingent difficulties in dealing with water, the actual cost of the two systems will differ to some extent, and the balance will be in favor of the solid wall. In the first place, the diame- ter of the cylinders will exceed the mean thickness of the solid wall, and the ce- ment, concrete, or brickwork, with which they are filled, would materially contrib- ute towards its construction. Calcula-
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VAN NOSTKAND'S ENGINEEEING MAGAZINE.
ting the cost of cast-iron panelling per sq. ft., and that of brickwork upon an average thickness in each case, the latter will have a slight balance in its favor. An instance recently came under our obser- vation in which there is no doubt the employment of cast-iron cylinders and plates would have been advantageous. The case was a very exceptional one. The bridge was absolutely a Jieur d'eau, the span being 50 ft. and the limit of headway from the surface of the water to the top of the metalling being only 2 ft. 6 in. The approaches were, therefore, vir- tually nothing, and consequently no wing walls were required. It wTas merely the question of the relative expense of sinking the cylinders and constructing the tem- porary dam. Apart from these consider- ations, there are one or two others which must not be disregarded when reviewing the whole subject. It is with pleasure that we are enabled to state that there has at last sprung up some desire among eng neers to render their works more prepossessing in appearance than for- merly. We vvill not go so far as to assert that they aspire to real sesthetical excel- lence on this point, but even this end may be ultimately attained. Sufficient progress has at any rate been made to warrant the statement that some regard must be had to appearance in all future designs. It is difficult to perceive how cast-iron framing and panelling would compete with masonry in this particular, without the incurring of expense that would be practically putting a veto upon the design. Genuine ornamental cast-iron work is of a very costly character. We have known as much as £140 per ton paid for it.
As a last consideration, that of dura- bility must not be passed over. There are so many different opinions respecting the behavior of cast and wrought iron when exposed for some time to the action of either salt or fresh water, that no posi- tive conclusion can be arrived at on the matter. Cast iron that has been exposed to sea water has been found so soft that it could be cut with a knife ; and, on the other hand, it has stood comparatively uninjured for years, in almost exactly similar situations. If we are not in a position to state the probable period that iron will remain in a sound condition under the circumstances alluded to, we
can at least safely predict that good masonry or brickwork will in any case last as long as iron. The existence of the ancient Roman sewers and walls is a proof that there is, or perhaps, rather, was, a description of brickwork which may be pronounced practically indestruc- tible. At the present day we may not quite come up to this standard of work, but it is possible we may go very near to it. It is alleged in favor of ironwork, that when it does rust the very rust itself acts as a protection against the further action of the cause that produced it. This may to some extent be true, but it must not be forgotten that rust never quite pro- tected iron yet, and the argument is of small value. The durability of cast iron in the position under notice will be lessen- ed if there is a tidal action at work, as the effect of alternate exposure to water and air is not confined solely to timber, but extends to metallic substances as well.
The Sherman Process, of which so much has been said and written in England during the past few months, appears to be losing favor. At the last meeting of the Iron and Steel Institute in London, such prominent iron-masters as Messrs. Menelaus of Dowlais, Hopkins of Cleve- land, and Mr. I. L. Bell, stated that the results following his process were quite inappreciable. Mr. Siemens said that when he first heard of the process which claimed with stn ounce of " physic " to drive out all the sulphur and phosphorus in a ton of iron, he knew such a result was impossible, and the experiments which had been made proved the correctness of his opinion.
eof. G-. Bischof, of Bonn, Prussia, is now in England with his apparatus for testing metals, which will have a place in the International Exhibition. The method of testing the quality of malleable metals and alloys consists in bending strips thereof alternately in contrary directions until they fracture, the number of times they are bent being duly record- ed ; whereby a trustworthy and accurate indication is obtained of the quality of the metal relative to standard measurements previously ascertained.
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ON THE IMPKOVEMENT OF THE CHANNEL SERVICE BETWEEN FOLKESTONE AND BOULOGNE, AND THE VESSELS PRO- POSED TO BE EMPLOYED.
By MICHAEL SCOTT, Esq, M. Inst. C. E. From the "Journal of the Society of Arts."
On the present occasion the author proposes to confine his observations to the Folkestone and Boulogne route. It may reasonably be inferred that one effect of the recent disastrous war will be to postpone, perhaps for many years, the expenditure of large sums on local im- provements in France. If so, it will be vain to expect that deep-water harbors should be constructed on the French coast, for the purpose of improving the communication with England. And it may be assumed that the formation of a deep-water harbor on the French coast would necessarily involve the construction of very costly fortifications for its defence ; and, having regard to the present exigen- cies of the national exchequer, and to the financial condition which is likely to obtain for many a year, it does not seem probable that the French Government would care to undertake such works.
Beyond this, the author holds that, even were the money forthcoming, the period is still distant when the traffic could be expected to yield an adequate return on a large additional outlay.
On the threshold of the inquiry it will be necessary to discuss the necessity or otherwise of such service being at fixed hours, independent of tide or weather. For the mails, fixed hours are no doubt essential, but Folkestone and Boulogne are not the mail ports, and it has been affirmed that a comparatively minor ex- penditure would render the mail service quite regular between Dover and Calais.
For passengers, it might be said that, being independent of tide, the most con- venient hours might be fixed and adhered to, whereas, with a tidal service, pas- sengers have to leave London and Paris at different hours, and sometimes to ar- rive inconveniently late.
No doubt change of hour is essential ; but it is not alone because the service is tidal that passengers have occasionally and necessarily to arrive late, but partly because of the length of time occupied in the journey ; and therefore if, as it will
hereafter be shown it is, it were practi- cable to reduce the time from London to Paris from 9| hours to from 8| to 8 hours, whilst the time for starting might not be altered, the latest time for arriving, and that only for a few days per month, would be about 10.30 p.m.
There is something also in the fact that, even assuming that an hour might be fixed which might prove most convenient for the majority of travellers, any one time would not necessarily be desirable for all. For example, to leave early in the morning might be most convenient for a business man, but it might not suit a delicate person or an invalid ; and it is an advantage of the tidal system, that a choice of several different hours is offered.
As, however, so much has been said in commendation of fixity of service, es- pecially as regards passenger traffic, let it be assumed that it would possess ad- vantages, and let us proceed to consider what practical objections exist to the introduction of such a system. To go no further, it will be sufficient to advert to the want of the depth of water in the existing harbors, which precludes the possibility of a vessel sailing at or near a fixed hour. Hence the advocates of such a service state that, before their views can be carried out, well-sheltered harbors, with deep water, must be provided on both coasts, and thus a fixed service would involve great cost.
What is the value of fixity of service ? Is it worth, and would it at present com- pensate for, an enormous additional expenditure of capital, not to mention augmented annual charges?
The author's proposals may be briefly summarized as follows : —
To provide for a tidal service between Folkestone and Boulogne, and taking care that the vessels, in size and cost of working, did not exceed the paying ca- pacity of the trade, to quote Captain Tyler's recommendation, by " larger* ves-
* See that gentleman's valuable Report to Board of Trade.
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sels with less movement in rough weather, more shelter, and better accommodation generally;" and, in order to effect this, to carry out certain improvements in the harbor of Folkestone, leaving the French authorities to do the needful at Boulogne, which will probably only include the works now being executed for increasing the backwater, and the arrangements for the landing and embarkation of pas- sengers at the west side of the harbor. The author has not had an opportunity of minutely examining the harbor of Boulogne, but, judging from general knowledge of the port, his strong im- pression is that little or nothing more would be necessary.
Before proceeding to describe the vessels recommended as suitable, it is important to draw attention to the fact that storms are the exception, not the rule ; and it seems only reasonable, whilst not ignoring the exceptions, that the ar- rangements made should have regard chiefly to the conditions which constitute the rule.
Captain Tyler says, in his report, that Captain Boxer, R.N., calculates that there are out of the 365 days, 29 days of gales and storms with heavy seas ; 102 days of good round sea and breezes ; 144 days with moderate weather and sea ; and 90 days of calm weather. Adding to the 90 days of calm weather 144 days of mod- erate weather and sea, we have 234 days, or about two-thirds of the whole year, during which it may be affirmed that on board moderately large vessels no incon- venience would be felt from either rolling or pitching, and during an additional 102 days such vessels would have but little motion. There are thus left 29 days of gales and storms during which it may be assumed there would be considerable motion, even in the largest ship. But it should be observed —
1. That gales and storms occur prin- cipally during the winter, when the pas- sengers are few, less than one-third of those travelling in summer ; and there- fore the number of days of bad weather is not a correct index of the number of persons who suffer from it.
2. Numbers of passengers avoid cross- ing in storms, and 4wait until they have blown over.
3. Any kind of vessel which could be employed would have motion in storms,
and, if very large, there would be corre- sponding difficulty in handling them in the harbors, whilst the fares, from the small number of passengers crossing in the winter, would not meet the expense of running vessels of extraordinary di- mensions, and, even if they possessed superior steadiness, it would not be re- quired in summer.
Having now come to the vessels which it is proposed to employ, the chief require- ments would appear to be —
1. That they should be steady, or have as little movement as possible in rough wreather.
2. That they should be so large as to provide sufficient shelter, roomy, airy cabins, ample promenade space on deck, and every convenience for a large number of passengers.
3. That they should have high speed.
4. That they should have exceptional steering powers, and their machinery be extraordinarily handy, so that in the wrorst weather they might enter and leave the harbors with safety, be easily swung in narrow and confined spaces, and be able to avoid collision with other vessels in thick weather.
5. That, in addition to ordinary holds, the vessels should be constructed to carry on deck the vans loaded with passengers' luggage, and a number of goods-wagons, sufficient, so far as the more valuable kinds of goods are concerned, to accom- modate the trade, and so transfer both luggage and merchandise (excluding very light and bulky articles) from one side to the other wuthout breaking bulk.
Having explained his views as to what gives to a ship stability and steadiness at sea, which he does not consider as being synonymous terms, the author says : —
In the case under consideration, what we have to do is to give up sail, and dimin- ish the amount of stability required, and then further to augment the steadiness by every reasonable means.
Much light has in recent years been thrown upon this question, and it is held that, cceteris jjaribus, we have a measure of the relative steadiness of vessels, in the position of the centre of gravity in rela- tion to the metacentre ; for it has been found that as these centres approach each other the stiffness decreases, but the steadiness increases, and vice versa. From this it follows that the nearer these centres
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can be brought the better, if we want a remarkably steady ship ; and this may be effected — first, by diminishing the breadth of the vessel ; second, by increasing the displacement or draught of water ; or third, by raising the weights of or in the vessel.
The effect of the opposite conditions is seen in ordinary steam vessels of light draught and high speed, which involves great weights of engines and boilers low down ; hence such boats are unsteady and roll violently.
Lastly, on this point, as affecting roll- ing, it has been found advantageous to have the means of winging the weights.
In vessels for the channel service it obviously would not do to restrict their breadth, because this would be to dimin- ish the space required for the comfortable accommodation of the passengers. Nor is it apparent at first sight how vessels with increased displacement and draught of water could make use of the existing har- bors, or how their weights^could be raised ; but a brief outline description of the pro- posed steamers will show how steadiness may be secured in the manner indicated without involving what appears to be the corresponding disadvantages.
The author proposes that the vessels should be about 300 ft. in length between perpendiculars, and very little more over all, and about 36 ft. in breadth. The ordinary draught of water to be 8 ft. 6 in. with all weights on board, including pas- sengers and their luggage and a consider- able quantity of goods ; and the vessels to be so constructed that, by the admis- sion of water ballast when at sea in bad weather, they would be steadied by having their draught increased to 11 ft.
The vessels to be propelled by two pair cf paddle-engines driving one pair of wheels amidships, and the speed to be 17 knots. Having two independent sets of propelling machinery, the vessels would require no masts, sails, or rigging.
It is further proposed that there should be three cabins for first-class passengers, viz., a main saloon, a ladies' saloon, and a cabin where refreshments could be ob- tained, and that there should be an after- cabin for second-class, and a fore-cabin for third-class passengers.
The first-class ladies' cabin would con- sist of a lofty saloon, before the machinery ; further aft would be the main saloon, of
large dimensions ; and in connection with all the cabins there would be lavatories and other conveniences.
In addition to the unoccupied main deck fore and aft, and over the machinery, and to the wing passages along each side of the saloon cabins, there would be an ex- tended promenade on the upper deck.
It is intended that the vessels should be constructed with double bottoms and double sides — in fact, except at the ends, the construction would be, to a great ex- tent, like a hull within a hull ; and, ex- cepting where the steam machinery inter- vened, there would be a lower deck, all fore and aft, and water-tight athwartship bulkheads. The result would be great strength combined with lightness, and what is very important, security in the event of collision.
There are other reasons for adopting the construction described, which need not at present be adverted to ; suffice it to say that the vessels would be almost un- sinkable, a matter of some moment, con- sidering that their course lies directly across the track of ships passing up and down the Channel. Spaces would be pro- vided into which water ballast could be introduced, and thus the draught in- creased and the vessel steadied at sea in bad weather; and when nearing port the water could be expelled and the vessel raised to her light draught again. By simple arrangements, these operations, namely, the admission and expulsion of the water, could each be effected in less than five minutes. Such is a general out- line of the dimensions and peculiarities of the proposed vessels.
Reverting now to the qualities which the vessels were to possess, it will be found that the first was steadiness in a sea-way. There being no masts or top hamper, and no sail to be carried, it is obvious that, as compared with rigged ships, the stiffness might be diminished with perfect safety.
The author does not ignore the fact that, the wind being favorable, sail stead- ies a vessel, but he wished to obtain a better result than sail would give ; and it should be remembered that the full value of sail (for this purpose) could only be i realized with the wind abeam or nearly so. Next, the form of hull might be such as, to a limited extent, to diminish the breadth at the water line without the dis- placement below; and by admitting water
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VAN NOSTRAND'S ENGINEERING MAGAZINE.
into the compartments prepared for it, the draught would be increased, and the displacement still further augmented.
The same operation (the admission of water) could be so arranged as in some degree to regulate the position of the cen- tre of gravity of the vessel in relation to the metacentre, arid cause these to ap- proach each other sufficiently near to pro- duce steadiness combined with perfect safety. Moreover, the proposed arrange- ment would give the commander unexam- pled facilities for regulating the trim of his vessel, to suit varying conditions of loading and weather, and so to produce the best results.
Without going further into the subject, it will be apparent to all, that a large, well-proportioned ship would have less motion in our channel seas than a small light vessel, dancing on the surface; and therefore that, the steamers proposed being (in displacement) about four times as large as those at present employed, greatly increased steadiness and immu- nity from sickness on the part of passen- gers might safely be reckoned upon.
The next requirement was, that suffi- cient shelter and comfortable accommo- dation should be provided for a large number of passengers. A comparison with the steamers at present employed in the service between Folkestone and Bou- logne will illustrate the superiority of the proposed vessels in this respect, for it would be found that the area of the deck and the area of cabin would be double that of the largest of the existing steam- ers.
The next requirement was that the vessels should have high speed. It will be enough to say that power sufficient has been reckoned upon to give a speed of 16 knots per hour, even in rough weather, so that, even in adverse circum- stances, the passage could be made in about 95 min. The time at