AGRICULTURAL SUBSTANCES CARRY FORCE 25 



most of her food into the valuable butter fats, storing 

 up a minimum amount in the form of protein in her 

 milk, or as a padding of fatty tissue on her body, is the 

 best machine for transferring a large portion of energy 

 from the pasture or grain bin into the valuable product, 

 butter. 



The illustrations shown in Figs. I to 6, inclusive, may 

 serve to show differences in engines, plants and animals 

 as to their effectiveness in changing latent energy into 

 active forms useful to man. They emphasize the great 

 importance of properly understanding the relation exist- 

 ing between latent and active energy as related to agri- 

 culture. 



The sciences related to agriculture. The theories and 

 facts of science have been grouped around the great 

 divisions of nature. Thus, there is the science of plants, 

 the science of animals, and the science of minerals. The 

 division of knowledge into groups continues with the 

 accumulation of facts, until there are many sciences. 

 Some of these deal mainly with the facts without direct 

 reference to the utility of the facts, while most sciences 

 ultimately affect some economic interest. Agriculture 

 has been wonderfully aided by the sciences, many of 

 which have a very close relation to agricultural produc- 

 tion and to the life of the farm home. 



In a general way the sciences may be divided into two 

 classes : The physical sciences, which deal with the 

 facts and laws of matter in which life may or may not 

 take part; and the biological sciences, which deal only 

 with living forms, both plants and animals. t Among the 

 physical sciences the following are especially useful to 

 agriculture: Mathematics, physics, mechanics, electric- 

 ity, chemistry, geology and meteorology. Since the 

 biological sciences treat of the life of the animal and the 

 plant kingdoms, they are equally useful and important, 

 for they throw light upon many things which have a 



