Bails.—Rails are generally of wrought iron, but steel rails have been extensively adopted where there is a continuous heavy traffic, and are found to reduce greatly the cost of maintenance, and promise to superspde wrought iron. Rails differ in shape and weight. The most common form is the " double-headed" rail, which is reversible. Another form, which was once used on the Great Western for the broad-gauge line. is known as the " bridge-rail;" and a •form frequently used on the continent, and generally on narrow-gauge lines, has a flat base formed by a flange on each side of the vertical web. The last two descriptions do not require chairs, but are fastened directly to the sleepers by spikes. Rails are generally 21 or 24 ft. long, and for light railways vary in weight from 20 to 45 lbs., and for heavy lines from 60 to 80 lbs. per lineal yard. Cross-sleepers are laid at 2 ft. 6 to 3 ft. 6 in. apart, usually about 3 ft., and on these sleepers the chairssof cast-iron are fixed and held firmly down by iron spikes driven into the sleepers. The ends of the rails are now almost always joined together by a plate of malleable iron placed on each side, called a fish-plate; two of these are used at each joint, and are bolted together by strong bolts passing through the rails. In the joining of the rails end to end, to make a smooth surface, great care is bestowed; perfect steadiness'in the required line.of direction is secured by means of wooden wedges •acting on the rails and the chairs.
Hitherto, the sleepers have been of seasoned native larch, as the most durable: but latterly, from the growing scarcity and cost of this article, sleepers have been made of imported timber from ports in the Baltic. They are sometimes creosoted to render them durable, but generally they are found to require renewal on account of splittiftg before they rot. Many patents have been taken out for methods of dispensing with wood sleepers. and substituting some more lasting material. Some of them are extensively used abroad, but they are scarcely to be found in this country.
Tunnels and Viaducts.—Tunnels are avoided as far as possible on account of their costliness. They are made only when the excavations would be more than 60 ft. in depth, or when land-proprietors force their adoption, in order to spare the amenity of grounds near a mansion. For this latter reason, some short tunnels are known to have cost railway companies as much as £50,000. Latterly,the execution of underground railways in the metropolis has offered examples of tunneling more extensive than were previously known in England, and at the same time popularized a method of subterranean transit almost as marvelous as anything in the way of viaducts. The Woodhead tunnel is probably the longest in Britain, being 3 m. 60 feet. All our tunnels have, however,
been cast into the shade by that through the Alps near Mont Cenis. The highest summit of the section immediately over this tunnel is 9,527 ft., and the summit-level of the tunnel, 4.246 ft.—about the height of Ben Nevis—above the level of the sea. It was completed in 13 years, cost about £200 per linear yard, the total length being 7.6 m., and was opened Dec. 26, 1870. The time occupied in passing through the tunnel by train is 25 minutes. A still greater undertaking, the St. Gothard tunnel, was begun in 1872. Its length is 9.2 English m.; the cost by estimate is £2,000,000; and 8 years was the time specified for completing the work.
Viaducts are frequently of stone, and of handsome architecture, but now commonly of malleable iron girders, of various forms, set in•stone or iron piers. In the construction of viaducts, there is a growing boldness of conception. Remarkable works of this kind are the great suspension East river bridge connecting New York and Brooklyn, more than a mile long, the central opening having a span of nearly 1600 ft.; and the St. Louis bridge, crossing the Mississippi by 3 arches, tlfe center span being 520 feet. But the longest bridge in the world at present is that across the Firth of Tay, Dundee, opened May 31, 1878. It was designed by sir T. Bouch, and cost £350,000. Length, 16,612 ft., in 85 spans, 11 of them being 245 ft. each. A magnificent suspension railway viaduct crossing the Forth at Queensferry is now in progress. The contracts for its erection ainount to £1,116,000.
Cost of Permanent Way.—Owing to the obstruction offered by land-owners, and their excessive claims for amenity damages, also the opposition of rival companies, the cost of railways was at one time very much greater than it is at present. The expenditure incurred in securing legislative authority to construct railways was likewise enormous. The parliamentary costs of the Brighton railway average £4,806 per m.; of the Man chester and Birmingham, £5,190 per m.; and of the Blackwali, £14,414 per mile! The cost of carrying the Liverpool and Manchester line was £27,000. It has been shown _ that the solicitor's bill for the South-eastern railway contained 10,000 folios, and amounted to £240,000. These few facts, however, afford but a feeble idea of the reck less wastefulness of capital on railway undertakings; it is universally allowed that, under a better policy, not only a much better railway-system might have been provided,. but a saving effected of at least fifty millions. At the end of the total average cost of all the railways in the kingdom was £35,943 per rq. open, or about double that of any other country.