in length, and weigh 19 oz. each. The screws have a hexagonal head, are also slightly tapered, and weigh 20 oz. each, their length being 6¾ inches. A creosoted oak ferule or socket is inserted in each hole in the chair, through which the screws are driven, so as to obtain a mechanical fit by simple means. The steel rails, which are laid in the chairs, are of the single-headed section, 30 feet in length, and weigh 900 lbs., or 90 lbs. per lineal yard. It may be mentioned that over bridges, and for some other special purposes, about 10 miles of rails have been laid upon the London and North-Western Railway which are 60 feet in length.
Each 30 feet rail rests on ten sleepers, and is secured in its place by creosoted oak keys 6 inches long, 3⅜ inches wide, and 2⅛ inches thick, driven between the rail and the chair, outside the rail. The fish-plates by which the rails are joined (Fig. 5, No. 2) are 20 inches in length, 5¼ inches deep, and weigh 54 lbs. per pair. The four bolts by which they are secured to the rails are square-headed, with a Whitworth thread 9 to the inch, the nuts being hexagonal.
A certain number of iron and steel sleepers have been laid down on the London and North- Western Railway experimentally, the first step in this direction having been taken eight years ago. The results have been varied, a percentage of the sleepers having failed, while, on the other hand, a larger percentage appear to be standing well; but, on the whole, a sufficient time has not yet elapsed to fairly test their durability.
Permanent way engineers insist that the first and last requisite for the maintenance of a sound and good permanent way is a perfect system of drainage. The formation requires to be kept as dry as possible, and to this end, if the material is of a porous nature, retentive of moisture, it should be well drained by means of
