Animals as Motors. 



491 



this table it appears that the hauling of two tons 

 on a wagon, at the rate of 2.f> miles pur hour, under the 

 varying conditions of the farm, requires a tea 1:1 to develop 

 energy at a rate ranging from 1.13 H. P. to as high as 4.98 

 II. P. of 550 foot-pounds per second. 



611. Horse Power Required to Plow. Taking the draft 

 of the stubhle plow as given in (305) and the mean rate 

 of travel for tl. team 2.5 miles per hour, the mean H. P. 

 required t< do the work, for furrows of different widths 

 and depth, is as given in the table which follows: 



Table giving the H. P. required to draw the stubble plow when 

 the soil is in medium condition. 



From this table and the one of (609) it appears that two 

 1,600-pound horses find their full capacity for work taxed 

 by the 14-inch plow cutting 4 to 5 inches deep; by the 12- 

 inch plow running 5 to 6 inches deep and by the 10-inch 

 plow running 6 to 7 inches deep. The team of 1,200- 

 pound horses finds its full ability taxed by the plow cut- 

 ting a 12-inch furrow 4 to 5 inches deep and a 10-inch fur- 

 row 5 to G inches deep. 



612. Increased Speed Diminishes the Traction Power. If 



the horse walks more rapidly than 2.5 miles per hour, or 

 at a slower pace, the force which he can exert changes also 

 and is less or greater than 100 pounds. Experience seems 

 to indicate that at speeds between f of a mile and 4 miles 

 per hour, and continued 10 hours per day, the traction will 

 be givon by the following equation: 



