If we place a globe in a vessel of water, so that the vertex shall only
just be covered, and place the globe eccentrically in the vessel so that
the centre of the vessel may not be too far from the outside of the
globe, and then impart an equable but slow motion to the water, in the
manner of a vortex; by viewing the reflected light of the sky from the
surface of the water above the globe, we shall be able to trace a
succession of dimples, originating at I and O, and passing off with the
current, and dying away. The direction of the fluid in these little
eddies, will be the same as the direction of the current in the main
vortex. If we displace the globe, so as to remove it far from the centre
of the vessel, and impart the same motion, the vortex I will be found at
E, and the direction of the current will be contrary to the direction
of the fluid in the vessel. In the case of the earth and moon, the
displacement can never change the position of the inner vortex much. It
will always be to the right hand of the central vortex in north
latitudes, and in consequence of the ether striking our globe in such a
position, the current that is deflected from its true path, by the
protuberance of the earth forcing it inside, is prevented by the
circular current of the parts nearer the axis of the vortex, from
passing off; so that a vortex is formed, and is more violent, _ceteris
paribus_, than the vortex at O.