152 THE CHEMISTRY OF CATTLE FEEDING 



on the level. The work done in hauling a laden cart uphill 

 may be regarded as done partly on the level and partly against 

 gravity, and the question can be investigated by considering 

 the two parts separately. The following example will serve to 

 illustrate the method. 



Let the hill, AB, be i mile [ = 5280 feet] long, and the 

 gradient i in 10, i.e. the vertical component BC is 528 feet, 

 and the horizontal 



AC = V f (AB) 2 -(BC) 2 = 5253-5 feet 

 And let the other data be as follows : 



Live weight of horse . . . . 1425 Ibs. 

 Weight of harness carried . . . 25 

 Weight of cart and contents . . 2500 

 The work consists of two parts, viz. raising the total mass 

 through the vertical distance of 528 feet, and moving it through 

 the horizontal distance 5253-5 feet. The latter cannot be 

 calculated from the data given, as the effort depends upon the 

 particular cart and road surface ; but for present purposes it may 

 be taken as one-fifteenth of the weight of the cart and contents, 

 and one-twentieth of the weight of the horse and load (harness). 



(a) To raise the mass against gravity 



(1425 + 25 + 2500) X 528 = 2,085,600 



(b) To haul cart on level 



^x 5253-5 = 875,583-3 



(c) Movement of horse and harness 



2S X 5^53 = 38o,878- 7 



Total work done (ft.-lbs.) 3, 342, 062*0 

 If the time occupied be known, the rate may be expressed 

 as foot-pounds per second, or in any other way, but it does 

 not affect the total amount of work done. 



