« PreviousContinue »
An objection has been raised to the atmospheric system, on the ground of the expense of the stationary steam-engines and establishments, and the liability to accident. This is replied to by Mr. Samuda as follows:
An important point will be here observ-| The Paliamentary Report states, that "in ed, that a considerable saving in the cost the cost of the maintenance of way, there of working is effected by the very means would be a difference in favor of the atmoswhich the public advantage requires-pheric principle." namely, by despatching trains as speedily as possible. Their weight is consequently diminished, and the piston, having less to draw, may be proportionably smaller in diameter. This reduces the cost of the pipe (which is the chief item in the first outlay of construction) in nearly the same proportion as the speed is increased, and as the rapid succession of trains is effected. In short, the economy of working and the advantage to the public are here identical.
Upon this subject we will only observe, that a consideration next in importance to that of security, is that of velocity-the power obtained by so much greater speed in carriage—and the manifold results which are connected, directly and indirectly, with this advantage. To these results we can only draw the reader's attention in a general way the value to the Government of a double rate of speed (independently of a reduced rate of carriage) is incalculable, for the transmission of despatches, troops, etc., but above all for the service of the Post Office. We may imagine, but cannot estimate, the vast effect on the revenue and business of the Post Office, which must accrue from the following advantages quick a succession of trains as might be desired,―a —a speed of transmission more than double the present,-a large reduction of the expenses of carriage, besides opening the possibility of employing railways in lines where they are now wholly inpracticable. Without considering the really most important gain to the nation-of the new facilities of correspondence-we limit our remark to the effects on the Post Office
"The objection as to the complexity and outlay attendant on a number of fixed engines, may perhaps be better answered by taking a review of the number and expense of these engines and the duty they are required to perform. On a line 30 miles long, supposing the average distance between the engines to be 3 miles, there would be 10 engines and air-pumps with their engine-houses; and if the railroad day over the whole distance (considerably were appointed for transporting 5000 tons per more than double the amount carried daily on any railroad in England), the expense of one of these stationary engine establishments would cost complete £4,200, which, multiplied by 10, will give £42,000-total cost on the must have escaped the notice of those urging whole line. But it is a fact which probably this expense as a drawback to the atmospheric system, if they were ever acquainted with it, that to perform a traffic of only 1700 tons per day, upwards of one locomotive engine per mile is necessary; and as each locomotive costs £1500, the total capital required for locomotive power on a railroad 30 miles in length would be £45,000; in first cost, therefore, there would be a saving of £3000 in favor of the stationary power; but this is far from being the most important saving. Every mill-owner in Lancashire and Yorkshire, and any person connected with mining operations, will readily admit that this outlay being once incurred for his mine, and his engine being once fixed on a steam engine to drive his machinery or drain terra firma, its deterioration, uncertainty of action, or annual expense of maintenance, is not a source of annoyance or anxiety to him. Another source of economy in working Five per cent. per annum on the cost will on the atmospheric system is, that the pow-more than cover all repairs necessary to be er expended may be exactly regulated ac- performed to it, and all oil, hemp, and tallow cording to the power required. M. Mallet used in working it. It is the exception, and not the rule, if a stationary engine once fixed, remarks on this point :meet with a derangement to render a stoppage necessary.
"Whatever be the load of the trains, the Rouen Railway Company pay 16. 10 per kilomètre for locomotive power; whilst on the atmospheric system the action of the engines might be diminished, and the power proportioned to the resistance, by making no more rarefaction than necessary. It would be possible, for instance, to use on ordinary occasions an exhaustion of twelve or thirteen inches ;this could easily be obtained in two minutes. Thus, at each trip, three minutes' work of the engines would be saved."-Page 52.
The annual expenses will be for repairs at 5
per cent. on £42,000
For coal for these engines (when trans-
Wages to engine-men and stokers
"The Liverpool and Manchester Railway is 30 miles long, and is the only railway that transports as much as 1700 tons per day over
its whole distance; and the annual expense of its locomotive department, including coke, is about £50,000 a year. Need we make any further comment, when the annual expense of power for the atmospheric system is £10,320, and for performing the same traffic on the locomotive system upwards of £50,000 is found necessary? Great as the pecuniary advantages have been shown to be, we must not forget to correct the third objection; viz., the erroneous opinion that the system is faulty because an accident occurring at one of these stations would interrupt the traffic on the whole line. Primâ facie, this argument is correct, but we have already shown how small the chance of accident is to a stationary steam-engine........ To make assurance doubly sure, a pair of engines and a pair of air pumps, each of half the requisite power, may be fixed at each station: should any thing cause one engine and pump to stop, the traffic would not be interrupted; the only delay would be the retardation of the train while passing over that section of pipe where only half the power was in action; and, until the cause of the stoppage were removed, the trains would be some five or six minutes more than usual performing the journey.-Page 17.
We must notice one more objection of a serious nature, connected with the employment of a single line of way,-viz. that an accident occurring at one of the stations, or any where along the pipe, may interrupt the traffic on the whole line. Upon this point Mr. Samuda remarks:
than any argument, however strong. In the whole of our workings, the column of mercury has never varied in height more than two inches on the same day; and as it requires eight times the number of minutes to destroy the vacuum in the pipe, when the engine is at rest, than it takes to raise it when in action, it follows that one-eighth only of the power (two horses) is all that is employed to overcome leakage. Perhaps the necessity of stopping the traffic of a line in the event of an accident, until the damage is replaced or the obstacle cleared away, should be regarded upon all railways as a peculiar advantage: by this necessity all chance of "running into" is avoided; and where stationary power is employed the difficulties of communication which a locomotive line has to contend with are overcome. By means of an electric telegraph, every engine-station along 100 miles of road may be communicated with in half a minute, and thus the traffic may be suspended and resumed at pleasure."-Page 17.
M. Mallet has examined this objection in the following passage:
"It has been said, should any accident occur on your single way, the traffic is all stopped; whereas with the two lines of a locomotive the other remaining. I will not dispute the road, if any thing happens to one you have validity of this objection, neither will I destroy it; but I can greatly lessen it in stating that very many of the accidents which happen on the locomotive lines, become an impossibility upon the atmospheric. No collision, no probable running off the rails: from whence then will accidents arise? From evil disposed
lines of locomotives are as open to their
"The next objection we have to meet is the interruption to the traffic from some derange-persons injuring the road? In that case, the ment in the pipe. This comprehends, 1st, an accident to the pipe itself; and, 2nd, from the composition not being effectually sealed.-An accident to the pipe can only occur from breakage, and, unless designedly perpetrated, could never happen at all. But for the sake of argument, we will suppose a pipe has been broken-no matter how; the time of removing it and replacing it with another would be considerably less than the time now necessary to clear off the fragments of a broken engine and train after a collision; and supposing a length of valve to require replacing, it could be done in less time than replacing a rail when torn up 4. In the last place we have to consider by an engine running off the line. If, instead the safety afforded by the atmospheric sysof one, there were one hundred places along the pipe where the heater had imperfectly tem, as compared with other locomotive means. This is a subject of such paraperformed its functions, the admission of atmospheric air through the composition in these mount importance, that, were any one places would only reduce the column of mer- system proved to afford increased security, cury a few inches: no stoppage or interrup- purchased even by increased cost of contion of the traffic could possibly occur from struction and working, a proper regard to this cause; and by comparing the quantity of public safety of life and limb ought to preair pumped out at each stroke of the pump ponderate over pecuniary motives. When with the quantity that will leak in at each imperfectly sealed spot, any such erroneous idea however, on the contrary, an invention will be removed. Perhaps on this head an offers the means of reducing the expenses appeal to experience will be more satisfactory of travelling, and at the same time of obJULY, 1844.
viating the possibility of accident, such a|may well be regarded as immovable, from benefit to mankind ought at least to be met its own weight and the strength with which it with every attention and encouragement. If any one feature characterizes the principle of the atmospheric railway, it is the very element of safety which lies in its construction and in the mode of its working. On this point we shall first quote the opinion of M. Teisserenc :
is fastened down, cannot run off the rail. other, would have even more difficulty in getThose which follow it, and are linked to each ting off the rails. But on a railroad, whilst the guiding carriage maintains its way, it is of little consequence if one of those behind misses the rail; its wheels may plough up the soil beside the track, but as it cannot get away no danger is to apprehended, and the worst that can happen will be a check in the speed. This roads upon the atmospheric system. Curves, also, which on the locomotive system may not be made less than 800m radius, may by this system be taken much sharper. I do not think that it is wise to reduce them as far as those of the road of Kingstown to Dalkey; but I look upon radii of 300m to 400m as quite possible."-Page 28.
"Au point de vue de la Sécurité.-Il est facile de montrer que le système atmosphé-is an important result for the construction of rique remédie à toutes les causes principales d'accident sur les chemins-de-fer en usage aujourd'hui. Quelles sont, en effet, ces causes: les collisions entre les trains, la sortie de la voie, la rupture des essieux des locomotives, les éboulements dans les grandes tranchées, les incendies. Avec l'appareil atmosphérique, pas de collisions, pas d'incendies, pas de rupture d'essieu; la voie modelée sur le niveau naturel du sol ne nécessite pas de grands mouvements de terre; le train tenu par un point fixe ne peut guère quitter les rails."Page 117.
This point is of such singular impor tance to the public, that we deem it desirable to compare the opinions of all those engineers who have examined and reported
Mr. Samuda remarks upon this subject upon the merits of the system, as it is esas follows:
sential that the fullest satisfaction should be afforded. We shall further quote a passage from Mr. Bergin's pamphlet, in which he notices a remark made in the Parliamentary Report, that it is a great element of safety for the source of power to be present with the train.
"There remains but one other matter to
"Beside these advantages, this system possesses others of still more importance to the public. No collision between trains can take place; for as the power cannot be applied to more than one piston at a time in the same section of pipe, the trains must ever be the length of a section apart from each other; and if from any cause a train should be stopped in the middle of a section, the train which which I think it necessary to advert; but that follows it will be obliged to stop also at the one is, in my judgment, of such paramount entrance of the pipe, as there will be no power importance, that, more than any other, it charto propel it until the first train is out. It is acterizes the atmospheric system; I mean the also impossible for two trains to run in oppo- safety of the passengers; not merely relatively site directions on the same line, as the power to other modes of transit, but the highest atis only applied at one end of each section. Atainable degree of absolute safety.......Now train cannot get off the rail, as the leading what the locomotive system is in point of carriage is firmly attached to the piston, which safety to the older modes of travelling, I travels in the pipe between the rails; and the believe the atmospheric to be to the locomotive: luggage and carriages cannot be burnt, as noin a word, as free from hazard as it is possible engines travel with the trains."
for any human contrivance to be. What elements of danger are there ?-collision is imThe opinion given by M. Mallet fully possible, all recognized causes of fracture of confirms this statement. "Firstly," he parts are almost altogether absent...... In speaksays, "this system, from not employing ing on this subject, the Reporters say, 'On locomotives, is exempt from all the dan-railways, it is a great element of safety that gers to which accidents to them expose us. ..In the second place, the risk of collision entirely vanishes, and perfect security may be enjoyed on that head, two trains never being able to run in the same pipe at once." Again he says:
"Upon an atmospheric railroad there is no possibility of running off the rails; or at least, if one carriage gets off the rails no accident can result from it. First, the leading carriage, firmly and closely attached to a pipe, which
and may be almost instantly turned off if any the source of power is present with the train, necessity shows itself for the stopping.-The presence of the engine, it is too well known, has not always proved a source of safety, as no inconsiderable portion of the very worst of railway casualties have been solely occasioned by it.
The latter part of the sentence is generally true; but in this respect there is no difference between the locomotive and the atmospheric systems; or if there be, it is in my opinion in favor of the latter, inasmuch as the means of turning off the power are still
more certain; the regulator or steam-cock of engine, unattended by any of its dangers, a locomotive-engine may stick fast, so that but others in addition. We may observe the engineman cannot move it; this I have that the weight of the engine being dis
more than once known to be the case. But
there are abundance of contrivances in daily pensed with, the momentum of a train is The necessary use, any one of which is adequate for uniting reduced in proportion. the travelling piston to the train, and in which weight in a train to convey 200 passengers no difficulty of separation, nor apprehension of upon the locomotive system amounts to 77 any derangement, can possibly exist. Be- tons; whilst on the atmospheric system it sides, even were this not the case, this sepa- is only 33 tons. So that the application of ration or casting off is not the only means at the break on the latter system will stop a the command of the conductor; in common train in half the time that it would with with the locomotive-train he has the break, and in addition he has the power of instantly locomotive engines. Mr. Bergin has alluopening a communication between the ex-ded to these in the aboye extract, but we hausted main and the atmosphere; this latter may notice still another.
of course is not so immediate in its action as When the power is turned off in a locoshutting off the steam in a locomotive, but motive engine, the momentum is checked combined with the break, which from the much by the break, and by reversing the action less weight and momentum of the atmospheric train, I know by frequent trials, (even at full of the engines. Upon the atmospheric sysspeed, and with the full motive pressure in tem, the required object is, as it were, also operation,) to be much more effective than provided for in a beautiful manner by the with a locomotive engine. I believe itpracti- natural action of the principle employed. cable to bring to rest a train moved by atmos- The conductor no sooner opens the compheric pressure, in as short a space as is con- munication between the exhausted main sistent with the materials of the carriage and the atmosphere (which is accomplished holding together." by the simplest means), than the very power which had before served to impel the train, now, when it is required to act contrariwise, tends to retard it. As soon as the air is admitted before the piston, not only is the motive power stopped, but the very momentum of the train accelerates its own stoppage, by compressing the air before the piston; so that its density acts as a check powerful in proportion to the speed, and diminishes only as the train stops.
Thus, so far from its being a cause of insecurity for the source of power to be distant from the train, the very reverse is the case. La locomotive porte avec elle," observes M. Teisserenc, un élément terrible de destruction, le feu, dont le catastrophe du 8 Mai, les accidents arrivés sur le chemin de Liège, sur celui de Tsarkoé-Selo à St. Petersbourg, ne font que trop ressortir le danger." Similar casualties of daily occurrence, attended with more or less mischief, might be quoted. The objection stated in the above extract has been carefully examined by M. Mallet, who says in conclusion:-"I must add, that it is not true to assert that there is no communication between the engine-man and the train. The barometer, which he has continually before his eyes, ever indicates the power he is exerting over the piston, and the increased or diminished velocity of the train is perfectly known to him by the rising and falling of the mercury. The barometer, also, is an instrument which it requires very little instruction to understand and
make use of.
But independently of the removal of this source of danger, it is manifest that, in the very point in which the Parliamentary Reporters ascribe exclusive safety to the locomotive system, the atmospheric has the advantage of not only possessing all the means of safety attached to a locomotive
The action of this same principle meets another question. It has been asked whether, supposing any leakage or accident should happen in the tube before the piston, in ascending a steep incline, the train would not run backwards by its own force of gravity? Supposing any such accident to happen, the same principle of nature which we have noticed would act to prevent this result: the momentum is proportioned to the inclination, and the greater the speed from this cause, the greater would be the compression of the air,-in fact the power to resist it. This beautiful operation of a principle of nature, so simple and self-adjusting, will be intelligible to every one.
We have thus noticed the chief points alluded to in the Parliamentary Report. A reply to many of the statements contained in it was published in the pamphlet by Mr. Bergin, of Dublin, to which we have alluded in this he examines at great length the result of the experiments instituted by the Parliamentary Reporters, and
their theoretical investigations, especially between the locomotive and atmospheric with respect to the estimated expenditure systems of railway. On an atmospheric of engine-power required to maintain the line, increase of speed does not increase exhaustion in the working main-the ex- the cost of transit: the amount of discharg hausting power of the air-pump, and the ing power expended during the transit of a proportionate amount of leakage in the given load, over a given distance, is the long valve and the piston in the main tube. Mr. Bergin examines, in a second class of observations, the remarks founded upon these calculations, which he considers as mere matters of opinion, and to which our attention has been more immediately directed. We shall proceed to notice the comparison of the merits of the two systems given by the Patentees :
"We will first notice the principal defects in railways worked by locomotive power. These are, the expenses consequent upon their formation and working, in addition to the impossibility of obtaining a speed beyond 25 miles an hour, without incurring a more than proportionate additional expense. For an engine that would draw 61.29 tons on a level at the rate of 25 miles an hour, would,-if required to travel 30 miles an hour, only be able to draw 29-66 tons, or, for the additional 5 miles in speed, a loss of more than one-half in power. These evils arise from the following causes: first, from the necessity of making the roads comparatively level, owing to the nature of the power employed. The whole power of the locomotive engine is not available to impel the train, because it has to drag itself and tender. Thus a great portion of its power is consumed even on a level; but that loss of power is greatly augmented when contending with the slightest ascent."-Samuda, page 21.
Here we must observe, that the velocity of travelling offers a remarkable contrast
same, whatever the speed; and at the same time a saving in the loss from leakage is effected also in proportion to speed. On a line worked by locomotive engines it has been clearly proved that an increase in the velocity of the train from 25 to 30 miles per hour, is attended with a loss of more than half the effective power of the engine. This disadvantage is also attended by another serious one when an engine has to draw a train up an inclined plane,-a difficulty which augments in an increasing ratio to the inclination; an engine that would draw 269-87 tons at 10 miles an hour, on a level of 1 in 1000, can only draw 84-07 at the same speed on a gradient of 1 in 100. Thus, as Mr. Pym well observes, "the power is lost or absorbed in the inverse ratio in which it requires to be augmented, precisely at the moment when it is most important to obtain an increase."
Wood's Practical Treatise on RailThe following table, taken from Mr. roads,* shows the gross load which a locomotive engine, capable of evaporating sixty cubic feet of water per hour, will drag, exclusive of the tender, at the undermentioned rates of speed, on different inclinations of planes. This will enable the reader to estimate the advantage which the atmospheric railway possesses :—
15 17 20 22 25 27 30
Inclination miles an miles an miles an miles an miles an miles an miles an miles an miles an
56 83 40-54 26.95
1 in 300.175-39 124-85 91-16 67-09 49.03 34.99 23-76 14-57
I in 200.138.48
Mr. Samuda states further disadvantages, of the locomotive system :
"Secondly, by the necessity of having great weight and strength of rails and foundation
consequent on the employment of locomotive engines. These engines (exclusive of tender) weigh generally from 14 to 15 tons each: and, * Third edition, page 581.