Longitudinal sleepers have been used to a large extent for bridge rails, it being supposed that with the broad continuous sleeper a lighter and shallower rail could be adopted, which would be equally efficient as a heavier rail on cross-sleepers. Excellent running roads have been made with longitudinal sleepers, notwithstanding the difficulty of making a good bridge-rail joint; but it is well to bear in mind that almost all the lines which originally adopted this form of permanent way have since reverted to the ordinary cross-sleeper road. The longitudinal sleeper road is an expensive road to lay down and maintain. The main pieces are of large scantling, must be of good quality of timber, and are consequently costly. The cross-pieces, or transomes, must be carefully fitted and secured with heavy ironwork. Where there is much traffic, the removal and renewal of one of the long timbers is much more difficult than the renewal of several ordinary 211 cross-sleepers. Again, decay may take place on only one portion of a main timber, but there is no alternative but to remove the entire piece. For gauges varying from 4 feet 8½ inches to 5 feet 3 inches, cross-sleepers are cut to the length of 8 feet 11 inches, and are generally rectangular in section, as in Fig. 303, measuring 10 inches in width by 5 inches in thickness. On some of the lighter railways with small traffic, sleepers are often used only 9 inches wide by 4½ inches thick, while occasionally on some lines, and in places where there is exceptionally heavy and constant traffic, sleepers 12 inches wide by 6 inches thick are adopted. Half-round sleepers, as in Fig. 304, are used on many lines because they are cheaper. In some cases the flat side of the sleeper is placed downwards, and the rail or chair is fastened into an adzed seat cut in the round side; and in the others the round side is placed downwards, and the flat side of the sleeper carries the rail or chair. Triangular sleepers, as in Fig. 305, have also been used, made by cutting the blocks diagonally, so as to obtain the greatest possible width. They were laid with the flat side upwards, and the apex downwards. They were difficult to keep packed, and have not been adopted to any great extent. With the exception of a limited number of larch and fir sleepers grown in the country, most of the sleepers for our home railways are imported from the Baltic. They are brought over in logs, or blocks, each 8 feet 11 inches long, some square and others circular in section, and when sawn down the middle, each block forms two sleepers.