THE

MONTHLY CHRONICLE.

THE GREAT WESTERN RAILWAY INQUIRY.

SINCE the investigation of the comparative efficiency of stationary and locomotive power for the working of railway traffic, which took place antecedently to the opening of the Liverpool and Manchester Railway, nothing has occurred in the progress of the art of transport by steam of equal interest, or likely to be attended with results of greater or more general importance then the inquiry which has arisen out of the dissensions among the shareholders of the Great Western Railway.

A carefully considered and well-directed course of experiments has been instituted with a view to obtain for the shareholders of this enterprise the most authentic information respecting the relative merits of the different modes of constructing railways, the various applications of locomotive power upon them, and the nature and amount of the obstacles which that power has to encounter. Neither expense nor labour has been spared to render this investigation full and comprehensive, and its results have been proportionately important in relation-not merely to the immediate question in which the investigation originated, but in relation to the powers and capabilities of railway transport generally. As this subject will embrace many points offering considerable interest to all that large section of the people of this country who desire to invest capital in such undertakings, or have occasion to avail themselves of the facilities which this improved method of intercommunication offers, we shall not think our pages unfitly appropriated if we devote, in the present number, some space to a statement of the leading facts which have been unfolded in this investigation, and to some explanation of the consequences with which they must be attended. It would have been gratifying to us, if what we had to state tended to confirm the splendid speculations in which those who have devoted their attention most to this subject, have for years indulged, anticipating the realisation of a rapidity of intercommunication as far exceeding that which is at present attained, as the present rate of travelling exceeds that which we were accustomed to on common roads; but, unhappily, circumstances have been brought to light in this inquiry which we fear will shiver to pieces all those brilliant anticipations, and will demonstrate that nature herself has interposed a limit to the speed of intercommunication between her children which cannot be passed, and many circumstances tend to show that the powers of steam have already brought us very close indeed to that ultimate barrier.

Since the results of this investigation have only been made public through the report which has just been circulated among the shareholders, we shall, in the first place, briefly advert to the circumstances in which it originated, state the manner in which it has been conducted, and finally explain some of the results which have attended it.

VOL. III.

All the great lines of railway which have been constructed, or are in progress, not only throughout this kingdom, but on the Continent of Europe, are constructed, with very trivial variations, upon one uniform principle. After the ground has been levelled, and the bottoming properly prepared, stone blocks, measuring from eighteen inches to two feet square, and twelve inches deep, are placed at intervals varying from three to five feet from centre to centre, according to the weight and strength of the rails intended to be used. On the centre of the upper surface of each of these blocks is placed a cast-iron chair, having a cushion of prepared felt between it and the stone block, and pinned down to the block by iron pins driven into wooden pegs previously inserted in holes drilled in the stone. These chairs are the props which, from point to point, support the rails, the stone block being the foundation of the chair. The rail is manufactured by the process of rolling in lengths, regulated by the distance between the chairs; thus, if the chairs be three feet apart, the rails are manufactured in length of fifteen feet, five chairs supporting each rail. If the chairs be five feet apart, then rails of the same length are supported by three chairs. If the chairs be four feet apart, the rails are rolled into sixteen feet lengths, and are supported by four chairs. The stone blocks are placed upon a firm bed of broken stone, or other well-consolidated matter, so that as little yielding as possible shall take place beneath them, and that the rails shall maintain their position with the utmost practicable truth and accuracy.

In those parts of a line where a valley or low ground is crossed by an artificial mound raised upon it, the earth of which such mound is formed requires a considerable time to become consolidated, and until it be consolidated, the use of these massive stone blocks would be attended with many difficulties and much inconvenience. On such parts of lines of railway, therefore, it has been customary to substitute temporary supports for the rails, by laying across the road rough beams of wood, usually formed of larch timber split through the middle, the flat side being placed downwards, at the same intervals as those at which stone blocks on other parts of the line are used. To these timbers the chairs which support the rails are pinned. This mode of construction has less stability than that already described, but as the mounds or embankments on which it is used are subject, for a considerable time, to subsidence or settling, as it is called, these cross timbers are found to be capable of being packed up with much less trouble, and at less expense than stone blocks. They are therefore adopted and continued on embankments, until the materials of which these embankments are formed become completely consolidated; the timbers are then removed, and stone blocks substituted for them, as in the other parts of the line.

Such briefly is the mode of construction of every principal railway in the kingdom, the Great Western Railway alone excepted.

But besides this uniformity which has been observed in the method of construction, our railways are also in accordance in another respect of vast importance, in the details of their operation. The rails on which the wheels of the carriages and engines roll, are all of them at precisely the same distance asunder. Let it be remembered, that the tires of the wheels of a railway carriage, unlike those of carriages used on common roads, have upon them a flange or ledge, which projects from the inside of the tire, and falls on the inside of the rail. It is these flanges or ledges which keep the wheels upon the rails, and prevent the carriage from running off at either side; they in fact give to the carriage, in relation to the rails, the character of a body which moves in a groove. Now this

being understood, it will be at once perceived that there exists between the carriage and the rails an immutable relation, so that carriages or engines constructed for a railway of one width, would be quite incapable of being used on railways of another width. Now, as it is obviously impossible to foresee the manner in which the innumerable ramifications of railway communication may intersect each other, or how a stream from one great channel of transport may become tributary to another, it was obviously a matter of paramount importance to provide that the carriages and machinery of any one railway should be capable of running or working upon any other. No reason, physical or mechanical, existed to guide the earlier railway engineers in the adoption of any particular magnitude for this important element. It so happened, whatever might be the chance which led to it, that the width of 56 inches obtained early currency, and with that width the Liverpool and Manchester Railway was constructed. The branches of that railway were necessarily constructed of the same gauge; the Grand Junction Railway, designed to connect Birmingham with Liverpool and Manchester, ran into one of these branches, and was consequently constructed in the same gauge; and, in a word, all the chief railways adopted the same uniform width.

That it was not the necessity imposed by each railway running into another of a similar width which induced this uniformity is, however, proved by the fact, that lines of railway between which there exists scarcely a possibility, much less a prospect, of a future junction, agree in it. Thus the railway from Vauxhall to Southampton, has the same width as that from Euston Square to Birmingham, and yet how improbable is it that the one line shall be carried into connection with the other! There is, in fact, a disposition to uniformity, unless some strong reason exists for dissent, and to this disposition only can be attributed the invariable adherence to the same gauge throughout the kingdom.*

To this mode of construction a few unimportant exceptions have existed in short railways, with comparatively small traffic. The Manchester and Bolton Railway, for example, is laid down according to a different method; and in America, where timber is cheap, and in many places stone not easily procured, and where the traffic on the line of railway forms, in most cases, an insignificant fraction even of the smallest amount of traffic of the least frequented railway of this country, other modes of construction are used. Thus beams of timber are laid on the surface of the ground, in the direction of the rails, and on these the rails are fastened down; the timbers thus supporting each rail of a line are held together at convenient distances either by cross timbers or iron bars. But though these methods of construction are used, it has not been any where pretended that they were the best, nor have they been used in any place where a considerable traffic is expected, and where stone is accessible at a moderate cost.

In the localities in which the London and Southampton Railway lies, stone is difficult to be procured, and accordingly the cross bearings of wood already described, called sleepers, are used as the support of the rails through a great part of the line. But it may be stated generally, that in a line constructed for any considerable traffic, and where stone blocks can be procured without an immoderate expense, they are always adopted as the supports for rails, except in the case of embankments already mentioned.

The same accordance which has taken place between the various railways of this country in their mode of construction, and their magnitude of gauge, has prevailed very nearly to the same extent in the method of Some short lines in Scotland have adopted a wider gauge,

working them. The magnitude of the wheels of the carriages and engines is a very important element in the working of these lines of communication. Numerous experiments made on the resistance of bodies moving one upon another have conspired to prove that the resistance of wheels and axles are inversely as their magnitudes. Thus a wheeled carriage rolling on a given surface will, other things being the same, suffer only half the resistance if its wheels be doubled in height; but in making this comparison, it is essential that the condition of other things being the same should be attended to. Thus, if by enlarging the wheels their weight be increased, that increase alone will, on its own score, produce a corresponding increase of resistance, and such increase must be placed against the advantage gained by increased magnitude.

But on railways another, and far more important consideration, presented itself in relation to the question of the magnitude of wheels. The danger to which railway carriages are most obnoxious is that of running off the rails. Unlike horse carriages, constructed with a perch, and provided with means of changing the direction of the moving power, railway carriages leave no power in the hands of the conductor, but will, as a matter of mechanical necessity, run forward in whatever direction accident may throw them. If, therefore, they run off the rails, they will certainly run off the road; and if this happen upon an embankment, their course will be down its side, nor can any effort or skill of the driver of the engine avert this misfortune. Now it is demonstrable that flanged wheels, such as those used on railway carriages and engines, will have a facility of escaping from the rails in the direct proportion to their magnitude: the larger they are the more liable are they, therefore, to this accident.

The wheels of the carriages and waggons which have been uniformly adopted on all the great railways throughout this country, and, we believe also, throughout Europe, have been three feet in diameter. The working wheels of the engine, on the magnitude of which the space through which the train is propelled at each stroke of the piston depends, have been, with a few exceptions, from four to five feet in diameter; and we are not aware that, of these exceptions, any have exceeded five feet and a half, and even these have been but few.

The working of railways having fallen into this uniform usage, the Great Western Railway commenced its operations, and the engineer, Mr. Brunel the younger, under whose directions it was placed, having devoted much consideration to the grounds on which the usages just explained had been established, arrived at the conviction that they had no sound foundation as a matter of general theory, and that if they were practically expedient, they were only so under particular circumstances, and could not be admitted as rules from which no departure was to be allowed. He appears first to have directed his attention to the method of construction, which he pronounced, in his Report and representations to the Directors of the Great Western Railway, to be essentially defective. In his Report of January, 1838, he says, —

"In all the present systems of rail-laying, the supports, whether of stone blocks or wooden sleepers, simply rest upon the ground, and consequently only press upon the ground with a pressure due to their own weight; this is trifling compared either with the weight which rolls over them, or the stiffness of the rail which is secured to them. The block or sleeper must lie loosely upon the ground; if you attempt to pack under it beyond a certain degree, you will only raise it: and for the same reason, it is impossible to pack under the whole surface of a block or sleeper; one corner or one end is unavoidably packed a little more than another, and from that moment the block or sleeper is hollow elsewhere. If this block yield as the weight rolls over, the rail itself, resting on the two contiguous