STATICS 



127 



Kellner 1 describes investigations upon the bodies of dogs 

 in which the following results were obtained : 



On comparison of the first and last columns it will be seen 

 that when the mass is increased [31-2-^3-2=] 975 times, 

 the body surface is increased only [10750-^-2423=] 4*43 

 times, i.e. animals (dogs) of tenfold mass have only about 4-7 

 times the extent of body surface. It is in consequence of this 

 that the loss of heat per unit of mass is much greater in the 

 case of the smaller animals. The loss of heat per unit of 

 surface is much alike in all cases. The larger animals, there- 

 fore, do not require so much food in proportion to their weight. 



Maintenance. It has been found that the daily food 

 required by an ox of 1000 Ibs. live weight yields about 35 kt. 

 of available energy. If the amount required by animals of 

 different sizes were directly proportional to the mass (live 

 weight) then (35 -f- 1000) would be the amount for an animal 

 of i lb., and M(35 4- 1000) for one of M Ibs. live weight. 

 Actually, however, this is not so. An ox of 800 Ibs. requires 

 about 30 kt. and one of 1600 Ibs. about 48 kt. per day. The 

 simple formula above must, therefore, be amended. When 

 the live weight (M) is less than 1000 Ibs. something must be 

 added to, and when it is more something must be deducted 

 from, the proportional quantities. 



In view of the fact that animals of tenfold mass have only 



of water is increased tenfold, the surface of the cylinder is increased only 

 4*6 times. Animals, of course, are not mathematical cylinders of water, 

 and the analogy, if pressed, might prove misleading. Nevertheless, a very 

 similar relation exists between their mass (live weight) and body surface, 

 as shown in the text. 



1 "The Scientific Feeding of Animals." 



