66 RAILWAY CONSTRUCTION. 



water which may be collected in the water tables; but more 

 particularly so is this necessary in a rock cutting, where the 

 material, being non-absorbent as compared with earth or gravel, 

 requires that all drainage must be carried away to the mouth of 

 the cutting. 



In carrying out railway embankments and road approaches, 

 it is usual to form the sides to a slope of 1 to 1, as shown on 

 Fig. 56. Occasionally the cuttings produce material which 

 might stand at a rather steeper slope, but considering the effects 

 which might afterwards be produced by heavy rains falling on 

 the sides, it is more prudent to adopt the flatter slope of 1^ to 1. 

 Some descriptions of clay will not stand at the above slope, but 

 require a slope of 2 to 1, or even 3 to 1. 



When proceeding with the earthworks, it is customary to 

 first remove and lay aside a layer, say 9 inches in depth, of soil 

 and earth from the seat of the embankments and top widths of 

 the cuttings, to be used afterwards in soiling the trimmed and 

 finished slopes of the cuttings and embankments. This soil being 

 removed, the actual work of the excavation can be commenced. 

 The working longitudinal section will give all the necessary 

 particulars as to position of the mouths of the cuttings and the 

 depths at the various chain pegs, and the top widths of the 

 cuttings can be ascertained by calculation, if on even ground, or 

 from the cross-sections if on side-lying ground, according as the 

 material may be earth, clay, or rock. 



For facility of carrying on the works, reliable bench marks, 

 or reduced level stations, must be established at convenient 

 distances along the route of the line, and from these and the 

 fixed chain-pegs the correct line of formation level can be 

 checked from time to time as the work proceeds. 



For ordinary earth or clay cuttings, the usual tools are 

 picks and iron crow-bars for loosening, or getting the material, 

 and shovels for filling into barrows, carts, or waggons. For 

 heavy earthworks, steam excavators are now largely employed. 

 Great improvements have been made in this class of machinery, 

 in the way of perfecting the method of excavating lifting, and 

 filling the material into the earth-waggons. 



In nearly all rock cuttings the greater portion of the material 

 has to be taken out, or loosened, by blasting with gunpowder, 

 dynamite, or other explosive. The number and extent of the 

 charges will depend upon the nature of the rock and its 



