INTRODUCTION. 



9 



So far as human agency goes, these chemical elements 

 are indestructible as to quantity, and not convertible 

 one into another. 



We distinguish various natural manifestations of force 

 which, acting on or through matter, produce all material 

 phenomena. In the subjoined scheme the recognized 

 forces are to some extent classified and defined, in a man- 

 ner that may prove useful to the reader. 



Act at sensi- 

 ble and in- 

 sensible 

 distances 



Act only at 

 insensible ■ 

 distances 



Repulsive 

 Attractive 



and 

 Repulsive 



Attractive ■ 



LIGHT 

 HEAT 



EOICTRICITY 

 Magnetism 



fGRAVITATION 

 COHESION 

 Cbtstallization 

 ADHESION 

 Solution 

 Osmose 

 APFINITy 

 VITALITY 



I Radiant 



j Inductive 

 Cosmical 



! Molecular 

 Atomic 

 Organic 



-Physical 



Chemical 

 Biological 



Within human experience the different kinds of force 

 are mostly convertible each into the others, and must 

 therefore be regarded as ffindamentally one and the same. 

 Force, like matter, is indestructible. Force acting on 

 a body may either increase its Kinetic Cinergy, or be 

 stored up in it as Potential Energy. . Kinetic (or ac- 

 tual) energy is the energy of a moving body. Potential 

 (or possible) energy is the energy which a body may be 

 able to exert because of its state or position. A falling 

 stone or running clock gives out actual energy. The 

 stone while being raised, or the clock while winding, ac- 

 quires and stores potential energy. In a similar manner 

 kinetic solar energy, reaching th^e earth as light, heat and 

 chemical force, not only sets in operation the visible ac- 

 tivities of plants, but accumulates in them a store of po- 

 tential energy which, when they sei-ve as food or fuel, re- 

 appears as kinetic energy fn the forms of animal heat, 

 muscular and nervous activity, or as fire and light. 



The sciences that more immediately relate to agricult- 

 ure are Physics, Chemistry and Biology. 



