induce passengers to travel by the canal at 3s. 6d. in preference to paying 5s. 6d. and 4s. 6d. by the railway, which can only be accounted for by the saving of time by the railway.

On examining the table of the relative cost of conveyance by canal and railway, we find the cost of haulage and boat-hire by canal, at ten miles an hour, equal to 3d. per ton per mile; while, for parcels and light goods, conveyed by the railway coaches, the haulage and cost of carriages are 1 d. per ton, at twenty miles an hour. In the case, therefore, of active competition betwee the two modes, we find the balance decidedly in favour of railways.

The result, therefore, of these comparisons of canal and railway communications is, with respect to heavy goods; where it becomes a question, whether a railway or a canal is to be constructed; that a railway is preferable, inasmuch as, while it affords as cheap a mode of conveyance for heavy goods, it presents a more economical and more expeditious means of transit, for all other descriptions of traffic. When the question relates to the construction of a railway, for the conveyance of heavy goods alone, to be brought into competition with an existing canal; unless there are other circumstances, in favour of the former, more than that of being a level railway, and of the same length as the canal, we find the latter will be enabled to compete with very great effect against such a railway. But when we are to determine as to the construction of a railway, for a mixed traffic of minerals, coals, or heavy goods, merchandize, and passengers, we find that a railway will be enabled to compete successfully with any existing canal; presuming that the interest of capital and amount of traffic are such, that the dues required to be charged on the railway, are not higher than those given in the cases upon which our calculations have been formed, of the

comparative cost of working the two systems of communication.

In our comparison, however, of the two systems of transit, we must not lose sight of the very important consequences, resulting to the commerce of the country, by the rapidity of communication effected by railways, which far outweighs any trifling balance of economy in favour of canals, if such even do exist; and, therefore, we presume, whenever the balance between the two modes, in any degree approach each other, a preference will be given to railway communication.

CHAPTER XIV.

ON THE CONSTRUCTION OF THE GREAT WESTERN RAILWAY, AND THE LOCOMOTIVE POWER TO BE USED THEREON.

THE Construction of this railway, being different from that of the Liverpool and Manchester, the London and Birmingham, the Grand Junction, and other great lines of railway laid down in this country; and being, in many respects, upon an entirely new system, and it being the intention of the proprietors of that railway to adopt a rate of speed much beyond that at present kept up upon the existing lines of railway; we have thought it advisable to give a short description of the mode of construction, and the plan of the locomotive engines to be used upon this railway. This should have followed the description of the plan of formation, of other lines of railway in Chapter IV., but as the Great Western railway is only at present in the course of formation, we deemed it advisable to obtain the latest information on the subject; and have, therefore, deferred obtaining it, as long as we could, previous to the work issuing from the press. Though this has caused a misplacement of this chapter, it has not been without its advantages; as it has enabled us to state the result of a trial upon a portion of the line, which, together with a description of the mode of construction, has been kindly communicated to us by Mr. Brunel the engineer.

§ 1.-Principles of the old System of forming

Railways.

The plan of formation of all railways is, in the first place, to form a track or road of as nearly a uniform level, or rate of inclination, as can possibly be done, from one extremity of the line to the other. This is done by cutting down all those parts of the line of the country, which are elevated above the general inclination or level of the intended road, and filling up all those parts, the surface of which is below the general rate of inclination of the proposed line of railway, as shewn in Fig. 1, Plate V. The whole length of the railway is, therefore, almost entirely composed of a succession of cuttings and embankments from one end to the other; and the line forming the upper surface of these cuttings and embankments, which ought to be a uniform level, or rate of inclination, is called the "base," or "formation line," of the railway. Upon all those parts of the line which compose the cuttings, this base will be quite firm and solid, being, in fact, the undisturbed strata of the earth; but upon those parts which are formed by the filling up or embanking, the base will not be firm and solid, until the earth or material forming such embankment becomes completely consolidated, and incapable of compression or shrinking; and it will depend entirely upon the nature of the material, what length of time will be required to transpire before such embankments become perfectly consolidated, so as to form a firm and unyielding base, or formation line for the railway.

Upon this base or formation line, as previously explained, a coating of ashes, gravel, or broken sandstone, of from eight to twelve inches is laid, for the purpose of

affording a dry and firm bed for the sleepers or blocks to rest upon; the ashes, gravel, or broken stone acting as drains to carry off the water into the main watercourses of the railway. The principle of construction of all railways being to form a continuous, uniform, firm, unyielding, and smooth surface for the wheels to run upon; it will at once be seen, that when the embankments yield, the uniform continuity of the line is disturbed, and, consequently, fresh material is required to be added from time to time, to raise the surface, until the embankment becomes perfectly consolidated.

Supposing the base or formation line of the railway perfectly firm, solid, and unyielding, then the rails are next required to be laid in such a manner, as that, when the engines and carriages roll along them, their weight should have no effect in depressing the sleepers or blocks into the coating, or of destroying the uniform level or line of the rails.

The mode of constructing the single and double wooden railways, at the early period of the formation of this kind of road, was, as previously explained, simply to lay down the longitudinal rails of timber, and the transverse sleepers, upon the surface of the coating of ashes; the timber of itself being very light, could have no effect in forming a solid and firm road, and, therefore, every time the carriages passed across the end of each sleeper, and along the rail, the coating would be compressed, the rails and sleepers would sink, and thus the level of the rails would be destroyed.

The mode of remedying this, was by constant manual labour, employed in pushing ashes or ballast underneath the rails and sleepers, until the coating became so firm, and solid, that the weight of the carriages had no longer any effect in compressing it; and until the rails did not yield, and sink to the pressure of the