232 



DRAUGHT AND HARNESS. 



and this of course creates backwater ; and then again, 

 we have the horse compelled to exert his strength at a 

 considerable angle to ,the towing-path on which he 

 works, and instead of progressing straight forwards 

 with his hind feet in the tracks of the fore ones, he is 

 compelled to traverse more or less. By lengthening 

 the towing-rope, both these evils may be diminished, 

 but they can never be altogether got rid of, for which 

 reason there is no kind of work so destructive of 

 horse-flesh as towing boats on large rivers where the 

 current is strong. 



Fig. 20. 



Let us now return to the horse drawing a wheeled 

 carriage, and take a two-wheeled one in the first instance. 

 If the two wheels were placed one behind the other, 

 as in a bicycle, one or more horses placed in front 

 in the line of traction might be harnessed each with 

 as short traces as possible. But the wheels being 

 placed alongside of each other, the case is very different. 

 Let x x, Fig. 20, I, represent the axle of a gig at right- 

 angles to the line of traction p a b c, and supposing 

 the effort of traction to be exerted successively at a b c, 



