Although the general practice has been to cast the chairs in one piece, chairs have been made in two pieces, as in Fig. 300, fastened together and to the rail by a bolt passing through the latter, the castings being secured to the sleeper with spikes. At first sight this pattern of chair appeared to possess some features in its favour. The castings were simple, keys were dispensed with altogether, and the under side of rail was not in contact with the cast-iron. A short experience, however, proved that the drawbacks far outweighed the apparent advantages. Holes for the through-bolts had to be punched at fixed distances in the rails, and although this could be readily done at the works, for the general use on the line it was necessary to resort to the tedious process of drilling by hand for a large number of holes on curves, and for rails cut to form _closers_. Sleepers.--Wood possesses so many suitable qualities that we can readily understand why it was early selected as the proper material for sleepers. It can be cut to any size and shape, holes can be bored, spikes can be driven, and bolts can be screwed into it without any difficulty and without causing injury to the timber, while the semi-elastic nature of wood absorbs the vibration of the rails and fastenings, and provides a sound-deadening seat so conducive to smooth running. Its only drawback is that it is perishable from wear and 210 decay. Were it not for this defect, railway sleepers of wood might be considered as simply perfect. With a view to greater permanency and durability, stone sleepers were tried. These consisted of square blocks of good hard stone, measuring about 2 feet wide each way and 12 inches thick. Holes were cut in the stone, and plugs of hard wood inserted. The cast-iron chairs were then placed on the top of the blocks, and the iron spikes driven through the chair-holes into the wooden plugs. The elements of permanency were there certainly, but a rougher road it would be impossible to conceive. The stone was solid and unyielding, there was a total absence of softness and elasticity, and the harsh noisy effect produced when running over the stone-block road very soon became intolerable. Stone-block sleepers were found to be a failure, and were all removed. On some of our old lines, numbers of them, with the chair marks plainly visible, may be still seen in loading banks, buildings, sea walls, and other works for which they were never originally intended, but for which their size and weight render them very appropriate. Wooden sleepers are used in two forms, transverse and longitudinal. In the former, as in Fig. 301, the sleepers not only carry the rails, but also preserve the gauge; in the latter as in Fig. 302, the longitudinal sleepers only support the rails, additional timbers and strong fastenings being necessary to maintain the gauge.