708 Some Results of Gravitation. [December, 
the matter would condense direcftly upon the centre, and no 
rotation could arise. In the latter case the centre of gravity 
affecting each particle would not be the centre of mass. 
There would be motion tangential to the centre, and 
stronger on one side than on the other, and rotation must 
arise. This might develop two species of atoms, a rotating 
and a non-rotating. But the latter, most probably, could 
not retain their aggregation, since they could present no 
elastic resistance to the impacts to which all atoms are con- 
stantly subjected, and they must therefore be exposed to 
disintegrating forces. 
But there is still another mode in which atom aggregation 
may have taken place, and this perhaps the most effective, 
if not the only, mode. In short, each atom may be a minute 
eddy, whirlwind, or cyclone in the ether. In the motions of 
the atmosphere it frequently happens that two opposing cur- 
rents of air meet. Unless in the improbable contingency of 
this opposition being exadt, their effort to pass each other 
results in a rotation, of which we have a familiar instance 
in the small whirls of air which so frequently arise. Similar 
phenomena are common in water, the meeting of any two 
diverse currents producing a revolving edd}\ In fadt, this 
result of the movement of fluids is a very common mani- 
festation, and varies from the great whirl of the cyclone to 
the minute whirl of the air or water eddy. But the ether is 
a fluid affedled by incessant motions. Minute winds of 
ethereal matter may be constantly moving in every possible 
diredtion. Such winds must constantly meet each other, 
and the inevitable result must be an eddy, or minute revo- 
lution of this fine fluid. But the eddy here may be ordinarily 
of such minute radius that the general centripetal attraction 
of the moving substance may suffice to retain its organisa- 
tion. In short, a revolving mass thus formed may persist 
in this condition through the influence of the mutual 
attractions of its substance. It would compose a permanent 
atom. 
If, then, we consider an atom as a mass of disintegrated 
matter, condensed about its centre of gravity, and rotating 
about a central axis, it would closely resemble the general 
conditions existing in a planet. But aggregation could not 
proceed so far as in the planet. The mass must continue 
gaseous. And the relations between its rapidity of rotation 
and its vigour of condensation might be far different from 
those existing in the planet. If the centrifugal energy of 
rotation was great as compared with the centripetal energy 
of condensation, the mass might assume a discoid shape, 
