166 



MECHANICS. 



ciple applies in both 

 cases. 



First, to ascertain 

 the friction, let the 

 platform he placed on 

 ^ a level, with the horse 

 I upon it ; then gradual- 

 f ly raise the end until 

 I theweight of the horse 

 I will just give it mo- 

 r„ tion. This will show 

 I the precise amount of 

 c the friction ; for if the 

 I. end he elevated one 

 I twentieth of its length, 

 I then the friction is one 

 X twentieth the weight 

 I of the horse and plat- 

 ^ form. 



Secondly, to deter- 

 mine the power, when 

 the end is still further 

 raised, measure the 

 difference between the 

 height thus given and the length of the platform. If, 

 for instance, the height of the inclination is one eighth 

 of its length, and the horse is found to weigh eight 

 hundred pounds, then the power is one hundred pounds, 

 or one eighth the weight of the horse. 



This rule will not, however, apply, when the draught 

 of the horse is added to its weight ; for it usually hap- 

 pens that the weight alone is not sufficient, without 



