186 W. A. Norton—Theories of Heat. 
[To be continued. ] 
Art. XXIL—On Dynamical Theories of Heat; by Prof. 
W. A. Norron. 
There are three conceivable modes of motion of such invariab/e 
-atoms—a vibratory or oscillatory motion, either rectilinear oF 
curvilinear; a revolution of one atom around another; or 4 
rotation of each about an axis. 
Let it be distinctly understood that the inquiry has reference 
only to atoms of ordinary or gross matier. There can be no ques 
tion that heat, in its origin, and generally in its manifestations 
within ordinary bodies, consists in some form of periodi¢ MOVE © 
ment, RSET Y with regularly recurring impulses communicated 
to the ether which fills all space and pervades the interstices of 
odies ; since waves of radiant heat cannot possibly have avy 
other origin. But the question is, whether the constituent 
atoms of bodies have this movement, or those of some form © 
ethereal matter intimately associated with these atoms. 
I. Can heat be any mode of vibratory, or oscillatory monen, of 
the atoms of gross matter. Against this notion of the origin, OF 
nature of heat, many serious objections may be urged. 
1. Lt implies rates of vibration inconceivably more rapid than we 
have any independent reason to suppose can take place in the inte- 
t bodies. The most rapid molecular vibratory motion that 
we actually know of, occurs when a vibrating body emits 4 
musical sound of the highest pitch that the ear is ca able of 
detecting. This is at the rate of less than 80,000 vibrations pet 
second, but an atom emitting the heat-rays of the red end of the 
