510 PHYSIOLOGY AT THE FARM. 



muscular exertion cannot be carried to any considerable extent 

 without a great increase in all the other kinds of work- 

 namely, vital work, heat work, and mental work, better named, 

 in such a case as that before us, nerve work. Thus, if the 

 outward muscular exertion of which a horse is capable in a 

 day as labour be rated at so high a figure as 12 millions of 

 foot-pounds, there remains a very large share of contempo- 

 raneous exertion for each of the other three kinds of work, or 

 nearly 10 millions of foot-pounds each for the vital work, for 

 the heat work, and for the nerve work. 



But on the assumption, which is that adopted by Professor 

 Playfair, of the muscular work, whether vital or external, being 

 sustained only by the carbon derived from the flesh-formers 

 that is, from the disintegration of muscular substance then 

 the energy attributable to the flesh-formers in the diet of rest 

 amounts to 10,132,500 foot-pounds; while that attributable 

 to the flesh-formers in the work-diet rises to 21,239,264 foot- 

 pounds, the difference being 11,106,764 foot-pounds, these 

 numbers being brought out thus, fractions apart, and the per- 

 centage of carbon taken at 52 oz. : 



100 : 52 :: 29 :15 



15 X 14,200 = 213,000 



13,125 x 772 = 10,132,500 foot-pounds. 



100 : 52 :: 60 : 31 



31 X 14,200 = 440,200 



4 ^f = 27,512 



27,512 x 772 = 21,239,264 foot-pounds. 

 21,239,264 10,132,500 . 11,106,764. 

 Thus, as the raising of 12 millions of pounds to the height 

 of one foot is the utmost estimate of the muscular ability of a 



