Page images

in addition to the rigidity of road required to sustain this weight passing over it on one carriage, the motion transferred to the wheels by the engines alternately on each side, causes a continual displacement or forcing out of the rails.

ready shown) on inclined planes. And, lastly, the chances of accident from collision, running off the rail, bursting of boilers, etc. From the foregoing remarks it will appear that the evils of the present system are entirely attributable to the use of locomotive power, and the reinedy must be sought for in the employment of stationary power in its stead."-Page 24.

With these disadvantages are contrasted the anticipated results of the atmospheric

system :

The third, and perhaps the greatest evil, is the heavy expense attendant on working a railway by the ordinary method; and this item is rendered more excessive by the necessity of having a large number of extra engines in store, to keep an adequate supply in working order. By reference to the half-yearly accounts of the Liverpool and Manchester Railway, the annual expense for locomotive pow-locomotive engines having to draw their own "1st. The loss of power occasioned by the er and coke is found to be from 50,000l. to 60,000l. a year, nearly 2000l. a mile per annum, on a traffic of about 1700 tons a day. This amount is exclusive of first cost and interest on the original stock."-Page 22.

out, and the same disadvantages exist in the application of ropes, which must be drawn along with the train, and become an increased incumbrance on inclined planes. The defects of ropes in other respects are too generally known to need comment.

weight is entirely avoided; and steep hills may be ascended with no more additional power than that actually due to the acclivity, as there is no weight except the train. There is no other known power which can be applied This item is one of serious importance. weight and friction with it. The ill effects of to locomotion without carrying considerable The Parliamentary Report states, that "in locomotive-engines have been already pointed respect of locomotive outlay, a line worked by locomotive engines, in order to be well stocked, should have an engine per mile in addition; this mode of working requires water-stations, engine-houses, repairingshops, etc." Thus the expense of all these engines, required to be constantly out of use, is exactly so much capital sunk, and yielding no interest. Nor is this a trifling matter, when we consider that each engine costs on an average above 15001., and that the expense of repairs on each in the year amounts to above fifty per cent. All this expense and loss upon capital invested is saved by the employment of a stationary engine, upon which the wear and tear is scarcely worth consideration. We recur to Mr. Samuda's statement:

2nd. The weight of the rails and chairs on the new system may be less by one-third than where locomotive engines are employed, as the carriages of the train will be too light to injure them. The annual charge of maintenance of way, will, from the same cause, be

reduced to a considerable extent.

3rd. The wear and tear of locomotive, compared with stationary engines, is as 18 to 1.

4th. By the new system the full power of the engines is always obtained; and on an incline, the additional quantity of fuel consumed in ascending will be saved in descending, as the trains run down by their own gravity. The expense of fuel will be further decreased, as the expense of using coal is only half that of coke.

"The fourth evil is the large consumption of fuel in proportion to the power obtained; which arises, in part from the great velocity in On the new system the velocity depends enthe movement of the pistons, preventing the tirely upon the velocity with which the air is steam from acting on them with full force; withdrawn from the pipe; therefore, by simwhich causes a back pressure on the pistons, ply increasing the air-pump, any speed may reducing their force in proportion to the vel be attained; and with a fixed quantity of trafcity at which they move. The power of the fic per diem, no considerable increase in the engine is thus constantly diminished as the ve- fuel consumed or any other expense is incurred locity of the train is increased. To so great for improved speed, further than the small adan extent is the combined action of these de- ditional power required to overcome the infects felt, that when travelling at 20 miles per creased atmospheric resistance. An actual hour, the effective power of the engine is re-saving in the first cost of a railway constructed duced to half that which would be obtained for high velocities may be effected, because, from the same quantity of steam generated by performing the journey in less time, a and fuel consumed with a stationary engine. greater number of trains may be despatched When travelling at 30 miles per hour, it is re- each day, and their weight diminished; thereduced to less than one-fourth; and at a speed fore the piston, having less to draw, may be but little exceeding 45 miles, the power is so smaller in diameter. The cost of the pipe far destroyed that the engine will scarcely (which forms the largest item in the first cost draw more than itself and tender. An addi- of this railway) will thus be reduced in nearly tional waste of fuel, to an immense extent, is the same proportion as the speed is increased." also occasioned by the loss of power (as al--Page 26.

M. Mallet, in his report to the French for a loan of money, on the security of their Government, makes an important observa- existing railway, to carry on the works. In tion on the effect which a reduction of the meanwhile, the Report above alluded to speed, in the passage of a train, exercises had been delivered to the Board of Trade, upon the motive force. In describing vari- which fully admitted the accomplishment of ous experimental trips which he made on the principle of the atmospheric railway, in the Dalkey line, he says, that in one jour- the following words: "We consider the prinney, when travelling at the rate of 45 miles ciciple of atmospheric propulsion to be esper hour,tablished, and that the economy of working increases with the length and diameter of the tube." With a creditable public spirit, the Government consented to assist in the trial of this national undertaking, and granted a loan of £25,000 to the Dublin and Kingstown Company. The Company however could not obtain a line of road without applying for a bill to Parliament; and to obviate the delay and expense which this would oc casion, the Board of Works granted them the use of ground in their possession, which had been used for conveying stone from the quarries near Killina to the harbor of Kingstown. The nature of this road presented every diffi

"During our course the barometer sunk to 21 inches: this fall was caused by our going on quicker than the air could be withdrawn. The air which remained in the pipe caused a condensation which lowered the barometer. In the following experiment, made with the same train, a contrary effect was produced. Set off at 8 inches, viz. with a power of 704 lbs. We went on very slowly, and saw the mercury rise to 20 inches gradually. In this manner the air-pump produced a vacuum quicker than we proceeded, and this is a very important point of the atmospheric system. If a slackness is produced by overloading a train, or if the train stops, the propulsive force instantly aug-culty to the formation of a railway; neverments."-Page 16.

theless the Patentees felt such a confidence in their project, that they were glad to have We shall not enter into further details of it tried and tested for the first time under the probable saving to be effected by em- circumstances of such unusual difficulty. ploying atmospheric pressure on rail-ways. The accomplishment of the work may on The calculations of the Patentees show a this account be regarded as doubly importlarge estimated reduction of cost in the con- ant. From the nature of the line of road, struction and laying down of a line on their a series of sharp and difficult curves was plan, and a saving of more than one-half in unavoidable, upon which no locomotive enthe annual cost of working; and we have gine could run without the utmost risk, and some guarantee for the general accuracy of at a slow pace. These are now passed with their calculations in a comparison of their the greatest ease and smoothness at sixty estimates with the actual cost of construc- miles an hour, and with loads attached of tion of the line at Dalkey. This gives us seventy-two tons at the rate of twenty miles. ascertained data. The cost of the appara- Another point has here been decided, upon tus complete, and placed on the line, is which in fact the applicability of this rail43007. per mile; and that of the steam-en- road to extended lines of traffic in a great gines, vacuum-pumps, engine-houses, etc., measure rests,-namely, the power of pass10007. in all, 53007. At the same time ing with facility from one section of pipe to we must here mention the remark made by another. At present, only one section of M. Mallet, in describing this apparatus, pipe is in operation, and consequently this that the engine" is evidently more power-experiment cannot be fully shown; its sucful than is required for working this road:" cess however is ascertained by the fact, he adds,-"I am informed that it would that the train has repeatedly passed off one make a vacuum in a pipe of six miles long: section, with the greatest ease and regularthey rarely work this engine to more than ity. The operation of the valve which half its power at present." divides the sections is simple and beauIn consequence of the success of the tiful,-we have already quoted M. Tiesexperiments at Wormholt Scrubs, the com- serenc's description of this,-and the simpany of the Dublin and Kingstown Rail-ple fact of the successful operation of this way, backed by the opinion of Mr. Pim, ex-valve is conclusive. If a train can pass pressed their desire to adopt the atmospher- without stoppage off one section, it must ic principle in an extension of their line necessarily enter at once upon the next, from Kingstown to Dalkey. In furtherance and there can be no question as to the faof this object they applied to Government cility of repeating this along a line of any

length: a hundred stations can as easily be from it, containing the results of trials upon passed as one. the Dalkey railway, which are of great interest :—

The excellent Report of M. Teisserenc, to which we have had occasion to refer, was founded on observations made upon the experimental line at Wormholt Scrubs. After detailing the difficulties and dangers attending the locomotive system, he thus compares it with the atmospheric :

obtenu d'une manière plus parfaite qu'on n'au"Après avoir reconnu que le vide était rait osé l'espérer, je me suis occupé de la vitesse. Je rapporterai ici quatre expériences.

1. Avec un convoi pesant 38 tonnes (la tonne anglaise est de 2240 livres), le baromètre marquant 25 pouces. l'on a monté en 3 minutes 15 secondes. Par prudence, l'on a employé les freins pour franchir les courbes, ce qui a produit un ralentissement. Le maximum de vitesse, dans cette expérience, a eté de 40 milles (16 lieues) à l'heure.

2. Avec le même convoi, l'on est monté en 3 minutes 7 secondes: maximum de vitesse, 45 milles (plus de 18 lieues).

3. On est parti, le baromètre marquant 8 pouces, avec le même convoi. Pendant le trajet, le baromètre est monté jusqu'à 20 pouces. Le voyage a été effectué en 4 minutes 30 secondes. Sur quelques points,l'on a marché à 30 milles (12 lieues).

4. Enfin, le baromètre marquant 25 pouces, l'on est parti avec un convoi de 69 tonnes. Le temps du trajet a été de 5 minutes 20 secondes.

"Le système atmosphérique est exempt des défauts que nous venons de reprocher aussi bien aux locomotives qu'aux machines à câbles. Son application dispenserait à la fois et du poids inutile du moteur dans le premier système, et du poids inutile de l'intermédiaire dans le second; elle permettrait l'excessive division, l'excessive multiplicité des trains, sans accroître les chances de collision, comme cela a lieu dans le système locomotif; sans augmenter la dépense, résultat de l'emploi des locomotives ou des machines à câble, elle fournirait un moteur dont la puissance, bien loin de diminuer avec le poils des objets à traîner, avec la roideur des rampes à franchir, tendrait, au contraire, à croître dans le même sens. Elle rendrait possibles toutes les vitesses avec des charges utiles considérables, sur les chemins les plus planes comme sur les railways les plus inclinés. Bien loin de nécessiter une application lente de la puissance motrice au départ, un ralentissement progressit à l'arrivée, elle permettrait d'accumuler à l'avance la force motrice, de manière à imprimer rapidement aux trains leur maximum de vitesse. Avec elle seraient impossibles et les collisions et les accidents résultant de la présence du feu. Les sorties de rail deviendraient extrêmement diffi- The following results of experiments ciles; les effets de la force centrifuge très peu subsequently made on the Kingstown and redoutables; puisque le train, composé au Dalkey line are extracted from the Railplus de deux voitures, serait étroitement lié à la voie. Enfin, construits pour recevoir des way Times' of December 2, 1843. Their voitures trois et quatre fois moins lourdes importance justifies our inserting them at les locomotives, les chemins n'auraient plus length. besoin de rails aussi pesans, de points aussi résistants; les collisions n'étant plus à craindre, pas plus que les encombrements, puisque les marchandises voyageraient aussi vite que les voyageurs, une seule voie serait suffisante. Rien de plus simple, d'ailleurs, que la théorie de l'appareil au moyen duquel on réalise ces nombreux avantages."-Page 108.


This Report awakened the attention of the French Government; and as soon as the works at Dalkey were in a sufficiently advanced state, they sent over another engineer, M. Mallet, Inspector General of Public Works, to furnish a second report. This recently appeared in the French journals, and we shall extract a few passages * Great credit is due to the engineers, Messrs. Samudas, for the skill and talent displayed in constructing the Dalkey railway, and improving many of the details of working.

Pour descendre, l'on a employé la gravité. A cet effet, l'on a rangé le piston de côté (ce que se fait avec la plus grande facilité), afin qu'il ne recontrât pas de tube. Le temps de la descente a été d'environ 5 minutes. Le mouvement était ralenti par le frottement dans les courbes. Je n'ai rien à dire de ce moyen, usité par plusieurs chemins de fer."

[ocr errors]

"Without the slighest hesitation, we have to state that the result of very minute investigation on the spot has fully confirmed the opinions to which we had previously come, from the scientific discussion of the principle and from the operations of the very imperfect apparatus at Wormholt Scrubs.

"The line between Kingstown and Dalkey is 13 miles in length, in which there is a rise of 714 feet, making an average ascent of 1 in 115, towards Dalkey. The main pipe between the rails, which is 15 inches internal diameter, commences at the Kingstown station, and is continued to within 500 yards of Dalkey. The communication between the main pipe and the the medium of a close pipe, laid outside the steam-engine (at Dalkey) is formed through trackway, and attached at the lower end into the main and at the upper end into the vacuum pump. A branch valve is placed at the junction between the close and open main, which allows the vacuum pump to act on the

main, or be shut off from it, at pleasure. The dimensions of the engine are,-cylinder, 344 inches diameter; stroke, 5 feet 6 inches; speed, 242 feet per minute. It works expansively, the steam being admitted in the cylinder at 40 lbs. above the atmosphere, and cut off at one-fourth stroke when the engine is at its full load; it is then expanded for the remaining portion of the stroke, and condensed in the usual way. The degree of cut-off is regulated by a cam worked by the governor, and is therefore proportionately shorter as the duty of the engine is less; but in no case is the steam admitted for a greater distance than one-fourth of the stroke. The vacuum-pump is double acting. The dimensions are,-diameter, 67 inches; stroke 5 feet 6 inches; speed, 242 feet per minute. With the above apparatus we saw a vacuum formed in the entire length from Kingstown to Dalkey-

[ocr errors]
[ocr errors]
[ocr errors]


m. 8.

Equal to a column of mer. 10 in. (or of an atmos.) in 0 56
15" (or %
) in 1 51
20" (or %
) in 3 30
For the purposes of observation, distance posts
were placed along the line at intervals of two
chains, every tenth post (or one-fourth mile)
having a distinguishing mark; and the follow-
ing was the result of some journeys made for
us during our visit:-

[merged small][merged small][merged small][ocr errors][ocr errors][merged small][ocr errors][merged small][merged small][ocr errors][ocr errors][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small][ocr errors][ocr errors][ocr errors][merged small][merged small][merged small][ocr errors][ocr errors][merged small][merged small][ocr errors][merged small][ocr errors][ocr errors][ocr errors][merged small][merged small][ocr errors][merged small][ocr errors][ocr errors][ocr errors][merged small][merged small][merged small][ocr errors][ocr errors][merged small]

The cost of the atmospheric apparatus complete, and placed on the line, is £4300 per mile; and of the steam-engines, vacuumpumps, engine-houses, etc. £1000; total, £5300. It would scarcely be useful to notice the other items that are necessary to complete a railway on this system, as the earthwork will vary materially according to the nature of the country through which it passes. In a difficult country the saving from adopting such "Journey A.-Gross load 62 tons; max-gradients as would be suitable for the atmosimum speed during trip for two chains was: 24 miles per hour; total time of journey, 4 minutes 48 seconds.

pheric instead of the locomotive, would considerably more than equal the entire £5300, while on a level or easy country a balance of "Journey B.-Gross load 72 tons; maxi-expense would remain against the atmosphermum speed during trip for 2 chains was = 20 ic system up to this point. In all cases the miles per hour; total time of journey, 5 min.

33 sec.

smaller quantity of land that would be required, the diminished size of the bridges, the lighter "Journey C.-Gross load 75 tons; maximum rails, the absence of all coke and water-staspeed during trip for 2 chains: 21-17 miles tions, workshops, and stock of locomotives, will per hour; total time of journey, 6 min. 2 sec. have to go to the credit of the atmospheric "Journey D.-Gross load 30 tons; maxi-system against the cost of vacuum tube and mum speed during trip for 2 chains was 51.5 miles per hour; time at passing 1 1-2 mile post 2 min. 57 sec.; total time of journey, 3 min. 24 sec."



"Among some

interesting experiments made at Dalkey are the following. The first In the same journal of December 16th series shows the uniformity of the sealing appeared the following additional details:-process. During the same day, and after the running of each train, observations were taken of the time required to re-form the vacuum to the height of 15 inches, which was as follows:


After the 4th trip the barometer rose to 15 inches in 1′ 45′′

[ocr errors]

"In following up the investigation, it should be observed that focal circumstances, amount of traffic, and steepness of gradients, will to a certain extent influence this consideration; with the view of rendering it as generally applicable as possible, we have made the calculations on a similar scale to that in use on the Kingstown and Dalkey line, and have deduced such of the working expenses therefrom as the time it has been in operation will allow. We apprehend that this scale will never have to be exceeded on lines of the largest traffic. Where it is decreased the cost will be proportionately lessened, so far as re22nd (C 15 " in 1 43 gards construction. The decreased scale will only influence the weight of trains. The "The second series shows the amount of speed can be preserved on the smaller as on leakage due to the longitudinal valve, as sepathe larger scale, by maintaining the same rela-rated from that due to the air-pump, travelling tive proportions between the vacuum-pump and the main.


[ocr errors]


[ocr errors]

in 1 40

[merged small][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small]
[ocr errors]
[ocr errors]


ing on the two systems. We have had occasion to cite many remarks contained in this Report, regarding the general merits of the atmospheric railway; and it is unnecessary to review it critically. It is the most valuable document that has yet appeared on the subject: the chief part is occupied with a minute and careful detail of the experiments which M. Mallet instituted on the Dalkey railway, and upon which his opinions are founded. These merit a close examination, and will be peculiarly valuable to scientific men interested in the subject of railways.

raised to 22 inches; the engine was then stop-fourth gives the comparative cost of workped and the tube was allowed to fill with air by the leakage (from all sources) into it. With the train at Kingstown, the gauge fell 18 inches, i. e. from 22 inches to 4 inches, in 11 33-100th, Advanced 1-4 mile in 10 88-100th, Advanced 1-2 mile in 10 76-100th, the leakage being at the rate of one inch in 36.83 sec. in the first instance, one inch in 36 sec. in the second instance, one inch in 35.91 sec. in the third instance,-showing the additional leakage from the long valve to be only so much as was represented by the gauge falling per inch of a second quicker in the first instance and of a second in the last, and the additional power to compensate this being all the increased haulage power required per half mile. This is an experiment of no ordinary interest, inasmuch as it confirms the notion that the advocates of the system have long urged for it, namely, that every extension of the length is attended with increased advantages, and that while the Atmospheric Railway is equally applicable to short as to long lines, it is by no means applicable only to the former, which its successful application on a short line has induced many to imagine."


M. Mallet examines

every advantage and disadvantage of the atmospheric system,-its applicability to existing and new lines, and under every circumstance attending construction. The English translation of this Report is of much less value than it might have been, had the French measures and values been reduced to the English equivalents; but a point of still greater importance (and which we are surprised not to see noticed by the translator) is, that all the calculations of M. MalWe had cited the above experiments, be- let are founded upon the French prices of fore the appearance of M. Mallet's Report; iron and of labor-naturally so in a report they however give substantially the same addressed to the French government; but results and figures, but in a more con- unless this fact is borne in mind, throughdensed form. Subsequently to the appear-out the calculations, and the difference noted ance of M. Mallet's first report in the between the English and French prices of French journals, a second and more detail-iron, the reader is liable to be seriously ed one, addressed by him to the French misled. Premising this remark, we obgovernment, has been published in Paris, serve that M. Mallet calculates that, in the and an English translation in London. That gentleman states, that "the fame of the success of this second experiment, made on a scale far greater than that at Wormholt Scrubs, spread itself into France. Immediately M. Teste, the minister, and M. Le Grand, Under Secretary of State of the Public Works, whose attention had been roused by the previous report of M. Teisserenc, desirous to know all the improvements and advantages of a system which might exercise so great an influence on the future prospects of rail-roads in France, gave me an order to embark for


cost of construction, the atmospheric system would effect a saving of one-seventh, and in the cost of working a saving of twofifths. The same calculation, made upon the value of iron in England, would show of course a much greater reduction. M. Mallet examines carefully and impartially every objection which has been, or is likely to be, raised to the atmospheric system; and in concluding this part of his Report he says:

"I do not think I have omitted any of the objections which have been pointed out to me. Several are worthy of being taken into consideration. But do any of them present insurThis Report is divided into four chapters: mountable difficulties? Are they of a nature the first contains a description of the line to induce us to abandon the invention? I do from Kingstown to Dalkey, of the apparatus, not think so, and therefore I advocate a trial. and details of experiments; the second If the system had already arrived at perfection chapter treats of the application of the at-no trial would be necessary; we should have mospheric system to railroads in general: but to lay down the works, certain of success; but in spite of the enormous step shown the third gives the comparative expense of to have been gained in Ireland, much yet relaying down a locomotive railway and mains to be done. Let its judges remember one on the atmospheric plan; and the what the locomotives were at their commence

« PreviousContinue »