CH. X DRAUGHT I 55 



narrow tires, a narrow tire gave somewhat the best 

 results. It may be observed, however, that the wide 

 tire is very wide, seven inches, and unfortunately 

 Morin does not give the dish of the wheel or the 

 drop of the axle, but he does say, p. 133, that, 'the 

 ' inclination of the axle-arm, obliging the wheel to 

 ' move about the axis of a cone, the rubbing of the 

 ' surface of the tire on the ground, which is the con- 

 ' sequence, tends to increase the resistance of the 

 ' wider wheel.' This is no doubt the whole reason 

 for the increase of friction, and since all axle-arms 

 are somewhat inclined, for the reasons already given 

 when treating of Wheels, it would seem that the 

 disadvantage of the grinding counterbalances an 

 advantage from increased width. * In farm wagons 

 used on soft ground and grass, there is no doubt 

 that a width of tire up to at least four inches, is an 

 advantage, and experience has indicated the same 

 thing at many sandy sea-shore places ; but to get 

 the best result, the wheel must be nearly straight 

 and vertical. As far as damage to the road itself 

 goes, it would seem from experiments, that on hard, 

 good surfaces, well united, and with a hard bottom, 



* In the experiments made at the Bedford Agricultural Show, 

 England, July 1874, with two loaded wagons practically alike, ex- 

 cept that in one case the inclination of the face of the wheel was 4 

 degrees, corresponding to an overhang of 3 inches or 1 ^ inch dish, 

 and in the other case \% degrees, \]/ z inch overhang or }{ inch 

 dish, the proportions of draught were -^ of the load for the more in- 

 clined wheel and -^ for the straighter wheel. 



