210 FORCE NOTHING BUT M V 2 . 



the singular advertisement to be seen here and there r 

 " To let, a room with POWEE." Power in what sense ? 

 Not surely the ability to spin or weave, or turn or 

 grind, or stamp or electroplate ? Certainly none of 

 these things, but only the force whereby any person 

 with the mental capacity and the materials needful 

 may do one or all of these things. Here, then, we 

 have, valued against a given weight of gold,, force in 

 its simplest aspect that is, motion measured as m v 2 

 or mass into the square of the velocity a wheel or 

 shaft of a certain size turning at a certain velocity. 

 In purchasing force, therefore, we purchase no power 

 of directing it towards any particular object. To do 

 that, we find we have no power except by taking ad- 

 vantage of the pre-existing properties of matter which 

 give it the capacity of taking on motion in a particular 

 way after its kind. In fact, the properties of different 

 kinds of matter may be defined as the capacity for 

 being moved each in its particular way ; while force 

 may be defined as the motion of matter, including the- 

 aether ; and it thus may be molar, molecular, or 

 sethereal. The indestructibility of force is thus a 

 corollary of the inertia of matter, for if matter cannot 

 start into movement of itself, neither can it stop of 

 itself, but only if its motion is transferred to other 

 matter or sether. The conception of a mass of matter 

 in motion from place to place, and the transference of its 

 motion to another mass by impact, involve no mental 

 difficulty requiring discussion. Nor does directing the 

 motion by taking advantage of the physical properties of 

 rigidity, &c., of matter in the form of machinery or 

 tools. At the same time, the impossibility of attribu- 



