i88i.] 
The Organisation of Matter . 187 
persistent allegiance. Should the earth come into contact 
with any exterior body the impacting energy would be only 
that of its motion through space, not that of its rotation on 
its axis. 
And another important question arises here. This is the 
question of the origin of the rotatory motion. Is it a trans- 
formation of the mass motion through space, or has it some 
other source ? If the former, the particles must cease to 
move through space without a transfer of their motion of 
translation to any other substance. Motion in one direction 
would change of itself into motion in two opposite direc- 
tions. Yet such a result is impossible. If the motions of 
the universe are accurately balanced in direction, no sub- 
stance can lose its motion through space except by transfer- 
ring it to some other substance. This is a fundamental 
principle of physics. 
In a motion of rotation there is equal movement in even 
two opposite directions. For the location of the centre of 
gravity of a mass depends on there being the same quantity 
of momentum on every side of it. Therefore, if it were 
possible that the quantity of momentum in any direction 
could be reduced, the centre of attraction would necessarily 
shift its position so as to restore the balance. But such a 
balance, once existing, could never be lost, since the energy 
of one hemisphere must forcibly compel an equal energy in 
the opposite hemisphere. 
Such a balance of motion in all opposite directions existed 
in every original mass ere rotation commenced, being what 
we know as heat vibration. Unless in the improbable con- 
tingency of the direCt motion of the mass embracing all its 
energies, through the loss of all reverse motion, some frac- 
tion of this energy must exist as heat motion. And this 
heat energy must be of equal vigour in every direction ; for 
if it were in excess in any direction, this excess would be- 
come new mass motion, either of the whole or a separated 
portion of the mass, or else would be lost as exterior impact, 
and leave the remaining motions in exaCt balance. The 
particles of the mass must therefore, in their individual 
motions, possess an equal vigour in every direction. But 
for rotation to arise something more than this individual 
balance is requisite. 
In any mass of matter possessing an excess of direCt over 
reverse motions, and therefore an excess of attraction over 
repulsion, this attraction, exerted between all the particles 
of the mass, necessarily generalises, and becomes in effeCt 
a single attraction exerted from the axis of movement of the 
