CH. X DRAUGHT I 65 



noted that it is difficult to compare such experi- 

 ments with accuracy, on account of varying condi- 

 tions. In this abstract of the Bedford Experiments, 

 for instance, the mean size of the front and hind 

 wheels is given ; in the full Report, their respective 

 sizes are given with the proportions of the full load 

 on each. The fief u res would be somewhat different 

 if the load of the four-wheeled wagon were placed 

 principally on the front wheels or on the hind wheels. 

 The inclination of the wheels, the character of the 

 axles, the equality or otherwise, in length of the two 

 axles, all affect the result. 



The subject may be summed up as follows : — 

 To obtain the least draught we must have the 

 largest wheel and the smallest axle ; the axle must 

 be highly polished, well fitted, but not too tight, and 

 profusely oiled ; the axle must be cylindrical and 

 horizontal ; and the wheel straight and vertical. On 

 a hard road with a vertical wheel, the width of the 

 tire, within reasonable limits, is unimportant ; on 

 soft ground, a wide tire diminishes the drauQfht. If 

 the wheel is dished and inclined, the increased width 

 increases the drauefht on a hard road. On a hard 

 road, it is not important that the two axles should 

 have the same length, but on a bad, or soft, road 

 the draught is increased, if the front wheels are 

 closer together than the hind wheels, because there 

 are four new tracks to break instead of two. 



On good, hard roads, the draught increases with 

 the speed, as is shown in the preceding tables, 



