196 W. A. Norton—Theories of Heat. 
II. Can heat consist in a motion of revolution of the atoms of 
bodies? The same objections that have been urged against the 
theory of atomic heat and light vibrations, will hold against 
the present hypothesis. The hypothesis seems, in fact, to be 
t a mechanical impossibility, consistently with the ordi- 
nary permanency in the properties of substances. Whether we 
regard the atoms as arranged in duplex or complex systems, 
these systems must be within the range of powerful reciprocal 
action, and hence must be exposed to mutual perturbations that 
should apparently be destructive of all permanency in their 
state, and so in the mechanical and physical properties of the 
substance to which they belong. 
IIL Can heat consist in a rotation of atoms about axes? The 
same objections still hold against this hypothesis as against that 
of atomic vibrations. To these it may be added, that upon this 
idea the expansive action of heat must result from ethereal 
vortices originating in the motion of rotation, but if such vor- 
tices have an outward or repulsive action, in a direction per- 
pendicular to the axis of rotation, the tendency should be the 
reverse of this in the direction of the axis; and hence atoms 
that have absorbed an additional amount of radiant heat (i. é., 
have taken on, under the impulses of the heat waves, a more 
rapid rotation) should exert an expansive action in certain diree- 
tions, but a contractile action in directions at right angles to 
these. : 
Other objections, of great force, might be urged against the 
doctrine that heat is some mode of motion of the atoms of gross 
matter, drawn from both physical and chemical considerations ; 
‘but those which have been presented will suffice. Unless they 
ean be effectively answered this doctrine must be unhesitatingly 
abandoned. 
Conclusions.—The results of the foregoing discussion seem to 
bring us irresistibly to the conclusion that the atoms of bodies 
must be made up of distinct parts bound together by certain 
forces; and that heat must consist in some movement of rela- 
tive displacement among these constituent parts of the atoms. 
If now we consider that every atom is capable of exerting upon 
surrounding atoms an effective repulsion at the more minute 
distances, and an effective attraction at certain greater distances, 
we are led to infer that the “ atom,” so-called, consists of a cen- 
tral attractive nucleus, surrounded by an envelope, or atmos- 
ase com of repulsive elements. We also readily 
scern the possibility that heat and light may consist in some 
mode of motion of this outer envelope, either in its elementary 
parts, or as a whole. Now we have independent evidence, 
afforded by the entire series of electric and magnetic phenom- 
ena, that there exists a subtile form of matter, eee up of 
