982 



ANNUAL REPOKT OF THE 



Off. Doc. 



TABLE V. 



Effect of Incliuation of Tractive Force. (U. S. Department of Agri- 

 culture.) 



The table gives the tractive force necessary to draw one ton over 

 the best macadam road of various grades, and the ecjuivalent length 

 of each mile of grade in miles of level road. 



The elfect of the inclination can be calculated from the following 

 formula: 



R = F X (^ \V, 



where F= force requii^d to draw the load on the level, a = the grade, 

 expressed by a fraction, W = the weight of the load in pounds, R = 

 force required to draw the load up the incline in question. 



According to Gillespie, if a horse can pull on a level 1,()()0 pounds, 

 on a rise of: 



1 foot in 

 100 feet he draws 900 pounds. 



.■)() feet he draws 810 pounds. 



44 feet he draws 750 pounds. 



40 feet he draws 720 pounds. 



30 feet he draws 640 pounds. 



25 feet he draws 540 pounds. 



24 feet he draws 500 pounds. 



20 feet he draws 400 pounds. 



10 feet he draws 250 pounds. 



