RAILWAY CONSTRUCTION. 21 1 



of several ordinary 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 8| 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 4^ inches thick, while occasionally on some 

 lines, and in places where there is exceptionally heavy and con- 

 stant 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. 



The preservation of timber from decay is a subject that very 

 early occupied the attention of engineers and all those interested 

 in railways. A railway sleeper is particularly exposed to 

 deterioration the lower portion being surrounded with moist 

 ballast, whilst the top portion is more or less uncovered two 

 different conditions in the same piece of timber. Several 

 processes have been tried, such as Kyanizing, Burnetiziog, 

 Boucherizing, etc., but the system which has given the best 

 results, and is now almost universally adopted, is that known 

 as creosoting. This method consists of forcing liquid creosote, 

 under considerable pressure, into sleepers or railway timbers 

 which have been prepared or dried by ordinary natural seasoning 

 or by special artificial means. Creosote is a dark, oily liquid, 



