As there is now almost a certainty that the broad gauge will be abandoned, it is only necessary to observe that upon that system the carriages are not only more expensive, but that the ratio of the dead to the useful weight is even more unfavourable than the one which prevails upon the narrow gauge lines. It may also here be added that upon almost all the continental lines of railway the carriages are much more commodious than they are upon the English lines ; and that in America only two classes of carriages are admitted, one for the white passengers, the other for merchandise and negroes. The American carriages usually run on eight wheels, coupled by what are called bogie frames in two pairs, in order to diminish the length of the tangential line formed by the fixed axles with the curves of the roadway they travel over ; the wheels, however, are very small.
We have already seen that, during the gradual development of the railway system, there has been a constant tendency on the part of machine-makers to increase the power and the weight of the locomotive engine, until it has at last attained the colossal dimensions before stated. Originally also the locomotives were made with only four wheels ; but the frightful accident on the Versailles line in 1842 raised so strong a prejudice against engines of that class, that they have been universally abandoned. Six-wheeled engines are now the only ones used on our English railways; sometimes with the tenders attached to the engines thus referred to ; and in them a represents the fire-box, usually made of copper, and surrounded by an outer casing of iron, so as to leave a space all round surrounded by water ; b represents tho boiler, with its horizontal tubes of about 140 or 150 in number, and made of brass, passing from the fire-box to the smoke-chamber, c; d represents the steam-chest, which in modern engines is made con siderably smaller in proportion than it used to be. The steam passes through the smoke-box to the cylinders at e, and there is upon the tube which so conveys it a throttle valve, under the control of the driver ; f and g represent the safety valves, and i the feed-pipes from the engine to the tender ; h represents the steam-whistle. Until very lately all locomotive engines were heated with coke, but a notable economy has been obtained on some lines by the substitution of coal for coke, by means of some alterations in the fire-boxes and the grates. The escape-steam in all locomotives passes off through the chimney above the smoke-hox. On some lines of railway the cylinders, instead of being placed inside the frame, are placed externally to it, so that the motion is communicated at once from the piston through the crank to the driving axle, without the necessity for forging a crank on the axle itself ; but there seems to exist a great disinclination on the part of the majority of engine builders to adopt this simple arrangement, perhaps on account of the condensation which takes place in the cylinders, and on account of the frequent ruptures of tho cylinders which occur in these engines. The driving-wheels of ordinary express locomotives, on Crampton's system, are now made 8 feet in diameter ; the cylinders about 18 inches diameter, and 2 feet stroke ; the heating surface in the fire-boxes is about 154 feet superficial, and the heating surface of the tubes about 2200 feet ; the pressure of the steam is often 120 pounds on the square inch. Such an engine, with its tender
filled with coke and water, would, at a maximum, weigh 36 tons ; the trailing or carrying-wheels are 3 feet 6 inches iu diameter.
The goods engines are usually made with four driving-wheels coupled, of from 4 feet 0 Inches to 5 feet in diameter, and two carrying-wheels, for the narrow-gauge lines, at least, where the inclimee do not exceed In 100. On the line across the Seemering, however, there arc four driving-wheels coupled, and mounted on one bogie frame, and six carrying-wheels mounted on another. The object aimed at in these cases Is to Increase, as far as possible, the adhesion on the rails ; and to secure the greatest possible length of boiler, and the greatest heating surface. The weight of an ordinary goods train may be considered to be about 150 to 250 tour; that of an ordinary passenger train about 60 to 100 tons.
Stations.—A very important part of the establishment of a railway consists in the erection of the intermediate and the end stations. The result of past experience seems to prove that it is by no means advisable to construct thee buildings, at the first opeuing of a line, in a costly or a permanent manner ; but rather that the true policy of a railway company is to purchase at once all the land that may be re quired, and only to erect the permanent buildings when the traffic has had time to develope itself. general rule, it would seem to be necessary to purchase an additional quantity of ground, beyond that which is required for the roadway, of about eight acres for a first class intermediate station ; and of about four acres for a second-class one; the terminal passenger station for a first-class railway will require an area of about 4 to 6 acres ; whilst the goods station of such a line will require about 25 or 40 acres, and the repairing shops, carriage depot;, engine houses, coke ovens, may require at least 12 acres. It may be added that in a large passenger station at a ter minus, as many as forty people are constantly employed ; and in a large terminal goods station there are often as many as 140 ; on a first-class intermediate station there are usually about ten people em ployed, and on a second-class station only about four. It has been found that the average length of sidings for turn-outs and goods stations, on lines with a large traffic, is not lees than from 12 to 15 per cent. of the whole length of the through way ; and the expense of the station buildings has been found to be not less than 2000/. per mile lineal of the distance between the termini, when no very costly or monumental buildings have been attempted. In all cases the embareation and landing of passengers should be effected under cover, and the same remark of course would apply to goods ; the passenger platforms should be finished at the level of the floors of the carriages.