282 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Sept. 



in the teeth of that, would amount, in my view of the case, to malicious ne- 

 gligence, and no accident could happen there but from that cause." 



Embankments. See Gradients, II. 



Ennme Houses. — The engine houses on the Croydon line will have chim- 

 nies like gothic towers, and will consume their own smoke. 



Enr/ine-men and Stokers. — Number and wages of engine-men and stokers 

 required according to the time during which trains may run. 



Express Trains. — They would not be necessary on atmospheric lines work- 

 ing constant trains. On long lines with long intervals between the trains, 

 express trains might be started between such trains — (Cubill.) 



fares. — The reduction of the fares on the Dublin and Kingstown line has 

 caused a great increase in the number of passengers— (Berjim.) 



Foreign Railways. — Some of the German lines are single lines, as are nearly 

 the whole of the Belgian ; the French are all double lines— (iocie.) 



Friction. — On the Dalkey line the inside of the tube is quite smooth; the 

 the piston requires no tallow. When the piston comes out of the tube there 

 is scarcelv anv perceptible heat — {Gibbons.) 



M. Hailett estimated the friction of the piston carriage, and lifting up, and 

 sealing the valve, at 35 lb. only. On the Dalkey line there is not much wear 

 upon the piston, which has a good deal of play — {Robinson.) 



Frost. — The frost has not affected the longitudinal valve on the Dalkey 

 line; it only requires a composition to be applied to it— {Gibbons.) 



Fuel. — The consumption of coat on the Blackw all Railway is at the rate of 

 5 lb. per horse power for every hour during which the engine is at work. 

 If coke were used instead of coal the cost would not materially vary. On 

 the Croydon line coke or anthracite coal will be used — {Field.) 



Gauge. — The gauge of the South Devon line will be the same as that of 

 the Great Western — {Brunei.) 



Gradients :— I. Generally. — II. Opinions as to the superiority of the 

 atmospheric system over the locomotive in ascending steep gradients. III. 

 Opinion that good gradients are more essential on the atmospheric plan. IV. 

 Gradients on various lines.— 1. Dalkey line. 2. London and Croydon line. 

 3. South Devon line. 



(I) It is the intention of the Dublin and Kingstown Railway Company, in 

 the event of getting their line from Kingstown to Bray (7 miles), to make 

 the highest point at the centre. One engine at the summit is capable of 

 drawing three and-a-half miles each way; the descent will be done by gra- 

 vitation — {Bergin . ) 



(II.) " When the locomotive engine is drawing a load upon a level, the 

 traction per ton is of course considerably less than when it is drawing it up 

 a steep incline ; but at the time of drawing it up a steep incline, the locomo- 

 tive engine necessarily requires an additional power to overcome its own 

 gravity, and is consequently not prepared to give the train even the same 

 amount of power it had been able to afford it on the level, at the very time 

 when the train requires a greater amount of power." 



Superiority of the atmospheric principle in ascending steep gradients ; dis- 

 advantages under which a locomotive engine labours in this respect exem- 

 plified — {Samuda.) 



" There is no atmospheric railway but the Dalkey line in existence; some 

 gradients upon the South Devon line will be 1 in 40. But that from Vienna 

 to Schonbrunn, which is now in the course of construction, admits of a gra- 

 dients of 1 in 30 ? — It is a parabola in section ; after passing Schonbrunn 

 and getting to the upper end, it finishes with a gradient of 1 in 30. No, 

 they go from 1 to 100 and 1 in 80, and they get to the 1 in 30 at last ; but 

 on the railway that is now about to be laid down from Paris up to St. Ger- 

 main's, I have recommended the adoption of the terrace at an inclined plane 

 of 1 in 30 ; and I believe it will be adopted ; I strongly recommended a 1 to 

 30 gradient for the last mile up to St. Germain's, with a lofty viaduct across 

 the Seine. 



(III.) Good Gradients are more essential on the Atmospheric Plan. Tak- 

 ing high velocities into account, good gradients are positively more essential 

 upon the atmospheric than upon the locomotive principle — {Stephenson.) 



" The moment you get into bad gradients you must have a high vacuum to 

 overcome the resistanee, because the word " gradient" is merely an equiva- 

 lent for " load." It is absolutely nothing else, because whether you have 

 resistance by gravity or resistance by load upon a level, it is precisely the 

 jame thing. There has been a great deal of misunderstanding, I am per- 

 suaded, upon this point. We find that the atmospheric requires to work at 

 a vacuum of 16 inches upon a level ; the more it deviates from that vacuum, 

 or rather, the more the gradients deviate from those which require that va- 

 cuum, the worse it is, and that becomes more and more sensible as you get 

 up towards a perfect vacuum. For instance: if upon a locomotive line we 

 increase from a level to a gradient of 1 in 100, the resistance is immediately 

 doubled or trebled ; therefore you have immediately to increase the vacuum 

 from, say, 16 inches, which is 81b. per ton, to 22 or 24 inches, and even 

 more ; therefore, you must necessarily either re<luce your speed or diminish 

 your load, which is precisely the condition of the atmospheric. In fact, if it 

 were not so, the atmospheric would possess some properties entirely at va- 

 riance with every mechanical power that we know of. If the velocity were 

 irrespective of the gradient, or in other words, irrespective of the load, it 

 would be tantamount to gaining power without the expenditure of power ; 

 therefore that power must follow the same laws as all other mechanical 



powers. If you wish to gain velocity you must either increase your power 

 or diminish the load ; but the condition under which you increase the power 

 is by increasing your vacuum, which is a more lavish expendilue of power. — 

 If you were told that it was possible to increase the diameter of the tube in 

 proportion to the resistance from the gradient, in that case you would no 

 longer hold that objection to be valid? — I should, even more so than before. 

 Will you explain your reason ? — If I increase the size of the tube, I diminish 

 the velocity immediately, with the same engine. — But you must increase the 

 engine ? — then it is a greater expenditure of power." 



In gradients exceeding 1 in 100 the locomotive power becomes extrava- 

 gant ; upon a gradient of 1 in 100, in certain states of the rad, the locomo- 

 tive loses its bite; it slips ; this slipping begins at about 1 in 176, or less 

 than that sometimes — {Stephenson.) 



IV. London and Croydon Line. — " Will you state the gradient upon that 

 portion of the Croydon line which you are about to open ? — Ihe extreme 

 gradients are I in 50. What is the gradient of the parallel locomotive line ? 

 — It is level at the same place. I will explain to the Committee how that 

 is : in passing from the Dartmouth Arms, where we begin our first experi. 

 ment to Croydon, the Dover and Brighton Unes branch out ; I was deter- 

 mined not to interfere with those lines; I took therefore, so to speak, a 

 flying leap quite over them, so that you will very soon see, 1 hope, a loco- 

 motive line with an an atmospheric line going over it, with a rise and a 

 descent again of I in 50 ; that viaduct is nearly completed ; it is rather a 

 curious thing in the construction of railways. — What is the length of that 

 gradient on each side i — The length would he 50 times 20 feet, or there- 

 abouts ; about 1,000 feet. What are your other gradients .' — They are very 

 flat ; 1 in 300, and 1 in 400, and so on ; we shall have one gradient of three 

 miles long at 1 in 100 ; that will be the second essay, and will not be finished 

 quite so soon as the first six miles in going from London ; but upon the first 

 atmospheric line now in construction we shall go three miles level, three 

 miles up a gradient of 1 in 100, three miles nearly level, and then half-a-mile 

 up and down 1 in 50, and then level again to Croydon." — {Cubitt's Ev.) 



South Devon Line. — "There will be very severe gradients upon the South 

 Devon line, but not upon that portion which will be opened in July ; the 

 portion which will he opened in July will be the first 20 miles out of Exeter, 

 which will be very light, easy gradients. From that distance to Plymouth, 

 the gradients will be very severe ; we have rises of 1 in 50, and in one in- 

 stance 1 in i2."— {Samuda). 



Grand Junction Railway. — The cost of maintenance of way on the Grand 

 Junction was contracted for, for seven years, at 250^. a mile, including guar- 

 antee and insurance from all accidents and liabilities — {Locke.) 



Guildford Railway. — It would require more capital to work this line on 

 the atmospheric than on the locomotive principle ; it is a single line — 

 {Locke.) 



The Guildford branch, six miles in length, is about to be opened in the 

 course of a week or two, and I have made a computation upon the number 

 of trains which we are going to run ; seven or eight trains a day, which is 

 the number of trains which we are going to run upon that line, would make 

 100 miles a day ; eight trains each way a day, a \s, per mile, would be 1,500/. 

 a year. Now, taking the cost of furnishing that line upon the atmospheric 

 system (it is but a single line) at 4,000/. per mile, which I understand to be 

 the estimate that has been given of the expense of these tubes, it would be 

 24,000/.; and two engines at 5,000/. would be 10,000/., making altogether 

 34,000/., from which I deduct the cost of two or three locomotives, though 

 one would do the work ; the trains are arranged that one shall do the work, 

 and there can be no fear of collision : but deducting 4,000/. for the cost of 

 those engines, leaves 30,000/. as the amount of capital for the atmospheric 

 railway, and the interest upon that at five per cent, is exactly the cost of the 

 locomotive power." 



Haulage. — Comparative cost on the Atmospheric System on a Line of 

 Railway 20 miles long, sending 6, 12, and 24 trains per day, each way respec- 

 tively — {Samuda.) 



fi trains per dav, each way : 



Coal— oOO lb. per hour, each pair of eoglDCS while working; and as each engine ia em- 

 ployed for 9 minutes per train, the quantity usefully burnt will be 75 lb., add for waste 

 while standing and getting up steam, 60 per cent, or -15 lb. 



1 20 lb. X 6 engines ^ gg ,^_ ^j j(,, ^^^ ,„^- . . . . . _ ,.^3 



2U miles. 

 Enginemen'B wages at each station, 1 man at 6s. Od., and one at 33. 6d., in all 

 7 stations : to this add 1 extra set of men for relieving the others; 



Ds. fid. X 8 sets = 3-80 



llj trains x -'0 miles 

 Repairs to engines, oil, hemp, tallow, and depreciation (I consider 130/. 

 per year per station ample, but have taken 200/. 

 Piston leathers . . - . . - - -= 052 



Charcoal = "-IZ 



\^'ear and tear of travelling piston ear . - - - - — U'lO 



Train conductors (or laen to attend piston carriage) 2 men at 5a. -= 0-5l) 



Per Train per Mile - 879 



I 



Maintenance of Groove : 2 men for 3 miles = pe 

 Coiuposilion \fil. per mile per year 

 ConUuuous valve, &f. hKH. per mile per year 



Per Train per Mile 



