50 Reply to a Criticism of Prof. Olmsted, 
ArT VIL—Reply to a criticism of Pror. OLMSTED, upon 
the arguments respecting the seed of heat, adduced 
by Dr. Hare. 
In the sumber of the American Journal of Science, for 
October last, I ajeerye some strictures by Prof. Olmsted, on 
an essay of mine, on the question whether heat can be motion, 
paplishes | in 1822, in Vol. 4 of the same work. 
The following passage is partially quoted, from Sir Hum- 
phrey Davy’s Elements, by the learned professor, as introduc- 
tory to his strictures.—I beg leave to quote it in full, * It 
seems possible,”” says Sir Humphrey Davy, ‘‘ to account for 
all the phenomena of heat, if it * supposed that in solids the 
particles are in a constant state of vibratory motion, the par- 
ticles of the hottest bodies moving with the greatest velocity, 
and through the greatest space—that in fluids, and elastic 
fluids, besides the vibratory motion, which must be conceived 
reatest in the last, the particles have a motion round their 
‘own axes, with different velocities, the particles of elastic 
‘fluids moving with the greatest quickness—and that in ethe- 
real substances, the particles move round their own axes and 
separate from each other, penetrating in right lines through 
space. . rature may be conceived to depend upon 
velocity of the vibrations ; increase of capacity on the m 
tion, being performed in see space 5 ; and the ie 
of temperature, during the conversion of solids or fluids into 
gases, may be explained on the idea of the loss of vibrato 
motion, in consequence of the revolution of particles round 
their axes at the moment when the body becomes liquid or 
aerifcrm—or from the loss of rapidity of vibration, in conse- 
quence of the motion of the particles through greater space.’” 
After his pee quotation of this passage, Prof. Olmsted 
s as follows : 
“He (Dr. Hare) has attempted to show, that the supposition 
that temperature results from the rs of the particles of heat- 
ies, subjected to a vibratory m s inconsistent with the 
laws of mechanics. ‘ It is fully ein; in mechanics, (says 
Dr. —) that when a body in motion is blended with, and thus 
to communicate motion to another body, previously at rest, 
moving slower, the velocity of the compound mass, after the 
impact, will — found by multiplying the weight of each body by 
pective velocity, and dividing the sum of the products by 
