244 Researches in the Theory and Calculus of Operations. 



resolves into force, and force re-resolves, but dies at last. 

 Force can produce motion if you let it, and force can stop 

 motion. Can any other thing do this? 



Activity tends to motion in space ; and as space is passive 

 in all directions, a sphere of material substance (force) will 

 emanate or radiate force in all directions about its central 

 point. Such emanation or radiation is experimentally known 

 to be true with respect to the several forces, gravity, heat, 

 light, etc. ; all of which have a material origin, and are there- 

 fore secondary, or generated forces. In the case of liquid and 

 of gaseous substances, the fundamental principle is that the 

 particles press equally in all directions ; and this suggests 

 the application of the same principle to the case of solids. 



In experimental physics, density and elasticity are in the 

 relation of mutually inverse energy : the greater the inten- 

 sion, the less the extension, and vice versa; the greater the 

 intensity of the atom, the smaller its volume, and the less 

 space is consequently occupied by the atoms and their mass 

 when congregated into body : 1° The atoms press against 

 each other so strongly that it is difficult to separate them ; 

 which agrees with the state of solidity. 2° When the densi- 

 tive and elastic energies are equal, the atomic intension and 

 extension are balanced, and are easily separated. The tran- 

 sition to this the liquid from the solid state is effected by 

 the application of the force of heat, which transforms inten- 

 sion into extension by promoting molecular vibration (Tyn- 

 dall). In the same substance, the radius of the fluid atoms 

 is larger than when in the solid state (notable exception of 

 water). 3° By the prolonged . application of heat to a fluid 

 mass, the atomic radii are further extended, the elastic comes 

 to surpass the den sic energy, and the aerial or gaseous form 

 arrives, in which the mass possesses great repulsive power, 

 and is proportionably compressible. 4° The fourth or ethe- 

 rial state of matter or force, comprising what have been 



