616 The Vehicle of Force. [October, 
momentum, tending to draw all these lines of motion to- 
wards their general centre of influence. 
If our principle be correct, these motions certainly have 
a gravitative influence. The equatorial regions of the earth 
rotate at a speed of about 1000 miles per hour. But the 
earth moves around the sun at a speed of over 1000 miles 
per minute — in round numbers, about 18 miles per second. 
Here is a vast mass of momentum all of whose influence 
must be attractive, since all its motions are in one direction. 
Its effect must be double. It must yield a centripetal influ- 
ence, adding to the great sum of terrestrial gravity. It 
must also yield a centrifugal influence, extending to all simi- 
larly moving matter in space, and aCting attractively upon 
the sun and its attendant planets. If such be the case the 
gravitative force of a planet could not be measured by its 
density or mass of matter alone, but must be to some extent 
influenced by its orbital momentum. 
Yet this could be only an aid, possibly only a slight aid, 
to the full force of gravitation, since the latter must be 
largely due to atom attraction, proceeding from the deep- 
lying fixed motions supposed to exist in atoms. 
It may be advisable here to consider the character of this 
supposed atom motion. The theory that atoms are minute 
vortex rings of ethereal substance has many points in its 
favour, although it is not easy to conceive how such vortex 
rings could arise in the original ether, since its conditions 
were certainly not those of ordinary fluids. Yet if the ether 
possessed inter-movement, with its consequent attraction, 
we can readily conceive of a condition arising similar to 
another probable condition of fluids, viz., an aggregation 
around a common centre of attraction, and possibly the 
formation of permanent spherical or discoidal masses 
through the influence ot rotation about an axis. And upon 
such masses, if forced to move through the ether, secondary 
vortex-forming influences might aCt, similar to those which 
aft upon moving fluids. Such a process of formation would 
give a double motion to the atom, it possessing not only the 
peculiar motions requisite to the vortex ring, but also a 
rotation of the ring as a whole around its axis, or the com- 
mon centre of its material. In such a case the atom would 
be at once a colleaion of individual particles and a single 
mass, these particles pursuing the vortex movements as 
individuals, and the whole ring its axial rotation as a mass. 
In such a rotating ring opposite influences must exist. 
Its parallel movements must yield an attractive force, and 
constitute centripetal influences, tending both to the centre 
