324 MR. J. C. DYER ON THE 



tion of the term is that which describes it as something 

 which produces or resists motion. When we think of 

 force we think of something moving or moved/^ 



This definition of the term force would be unexception- 

 able, if what is called force were held simply as indicating 

 the properties of the bodies in which it acts, and not as a 

 something, or energy, existing by itself as an entity apart 

 from matter, but as a part of it. "Were it merely intended 

 to declare that the sum of the mechanical forces, as gravity, 

 inertia, and elasticity, is a constant quantity, just as is that 

 of the bodies in which these forces are inherent properties, 

 then there would be no grounds for asserting this fact as 

 disclosing a " great new doctrine ; '' for the indestructible 

 nature of matter, and of its properties, were physical truths 

 known and taught in our childhood. 



The relations of matter and force — at least as regards 

 the mechanical forces — have been set forth in such ample 

 detail, comprising all known facts, in the elements of phy- 

 sical science, that it would seem needless to repeat the 

 fact of the unchangeable nature of the material universe, 

 both as to the amount and the kind of forces pertaining 

 to matter, but for the enunciation of theories implying 

 such changes ; wherefore to treat of the conservation of the 

 natural forces, and of the disappearance of " one kind of 

 force and reappearance of another kind,^^ must be held as 

 employing unmeaning or misleading terms. It is not that 

 any of the forces themselves can disappear, or be changed 

 from one to another kind of force, but that the motions 

 generated by them may cease, or be rendered quite uniform 

 when the moving forces are exactly balanced, by their ac- 

 tion in opposite directions. 



In short, the term force, used in an abstract sense, and 

 without defining the kind of force intended, is worse than 

 idle or unmeaning, because when so used by eminent phy- 

 sicists it cannot fail to puzzle and mislead the younger 



