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EFFECT OF GRADES 



CH. X 



slope, where a portion of the weight has to be raised 

 vertically. The proportion of the weight thus lifted 

 is directly as the height of the inclined plane is to its 

 horizontal length, and is, therefore, easily computed. 



If a road rises one foot in every ten of its length, 

 or, in other words, has a grade of one in ten, the 

 power of the horses must be exerted to raise one- 

 tenth of the weiofht of the coach all the time that 

 the coach is ascending the slope, and this resistance 

 must be added to that of the rolling- friction and the 

 axle friction. 



On all except very slight grades, this resistance 

 becomes important, as the accompanying table 

 shows. 



