156 Count Rumford’s Enquiry concerning the 'Nature of Heat, 
of heat and absolute cold, or a total privation of heat: hence it is 
evident, that all attempts to determine the place of absolute cold , 
on the scale of a thermometer, must be nugatory. 
It seems probable that motion is an essential quality of matter ; 
and that rest is no where to be found in the universe. 
We well know, that all those bodies which fall under the 
cognizance of our senses are in motion ; and there are many 
appearances which seem to indicate, that the constituent particles 
of all bodies are also impressed with continual motions among 
themselves ; and that it is these motions (which are capable of 
augmentation and diminution) that constitute the heat or tem- 
perature of sensible bodies. 
The only effects of which we have any idea, resulting from 
the action of one body on another, are a change of velocity, or 
a change of direction, or both. We perceive, it is true, that 
certain bodies have a power of affecting certain other bodies at 
a distance ; but this is no proof that the effects produced are es- 
sentially different from those which result from collision ; for, 
if an elastic body be interposed between the two bodies, their 
actions on each other may be communicated through such in- 
termediate elastic body, which, when the action is at an end, 
and the effects resulting from it on the two bodies have taken 
place, will be in the same state precisely in which it was before 
the action began. 
If a bell, or any other solid body, perfectly elastic, placed in a 
perfectly elastic fluid, and surrounded by other perfectly elastic 
solid bodies, were struck, and made to vibrate, its vibrations 
would, by degrees, be communicated, by means of the undula- 
tions, or pulsations they would occasion in the elastic fluid 
medium, to the other surrounding solid and elastic bodies. If 
