48 THE PRINCIPAL U8BS OF WOOD. 



always, from the first, been a matter of great, and, it may also be 

 said, insuperable difficulty. The wood required for sleepers must be 

 perfectly free from all defects and unsoundness, as durable as pos- 

 sible, and possess great transverse strength. Besides this, it must 

 be hard enough to hold bolts well, and to resist crushing of the 

 fibres, especially when flat-footed rails are used. Such rails are 

 fixed and held in place by dog spikes, which, if the wood is at 

 all soft, are liable to crush the fibres laterally, and thus get loose in 

 their holes through the constant jarring and jolting to which 

 the track is subjected by the moving trains. This danger is 

 most to be feared on curves, on which only very hard woods 

 should be used. Die-square sleepers containing no sapwood at 

 all are of course the best, but about an inch of sapwood on the 

 two edges of the upper face are often not objected to, and half- 

 round sleepers, obtained by sawing a log in two, are often used 

 without any of the sapwood being removed. But in this last case 

 both the diameter and thickness of the sleepers are fixed in ex- 

 cess of the scantlings of a die-square sleeper, and the seats for the 

 rails are adzed flat. If the log to be sawn in two is not straight, 

 or one end is much thicker than the other, this defect must be 

 remedied by adzing or Bitching off with a saw the irregular sides 

 or excess width, as the case may be. 



The principal woods used for sleepers in India are teak, sal 

 and deodar. Hardwickia binata is easily the most durable of all, 

 but it is so extremely hard that special machines are required to 

 bore the holes for the spikes, and even then the holes are bored 

 with much labour. 



It was the great demand for sleepers (when the construction 

 of railways was first taken up with vigour soon after the mutiny) 

 and the consequent havoc carried into our forests by the contrac- 

 tors that first directed the attention of Government to the conserva- 

 tion of our forests. The supply was found to be totally insufficient, 

 and the question of substituting metal for wood was at once taken. 

 The Oudh and Rohilkhand Railway laid its rails on cast-iron pots 

 connected with an iron tie-rod. The pot sleepers were soon found 

 to be inferior to wooden ones as they produced a rough way, and 

 the constant jarring of the passing trains rendered the metal very 

 crystalline and brittle. Moreover, owing to the way in which the 

 pots were connected, if a single one broke, under a moving train, 

 the result was usually the dislocation of a long length of line. 

 Hitherto the most successful metal sleeper used in India is per- 

 haps the trough-shaped one, with which all the new sections of the 

 North-Western Railway have been laid. It is made of a rolled iron 



