f the earth upwards, and knowing
from observation that at 18,000 feet above the surface, the density of
the air is only 1/2, it follows, (in accordance with the principle that
the density is as the compressing force,) that at 43 1/2 miles high, or
18,000 feet _below_ the surface of the atmosphere, the density is only
1/8000 part of the density at the surface of the earth. Let us
take this density as being near the limit of expansion, and conceive a
hollow tube, reaching from the sun to the orbit of Neptune, and that
this end of the tube is closed, and the end at the sun communicates with
an inexhaustible reservoir of such an attenuated gas as composes the
upper-layer of our atmosphere; and further, that the tube is infinitely
strong to resist pressure, without offering resistance to the passage of
the air within the tube; then we say, that, if the air within the tube
be continually acted on by a force equal to the mean centrifugal force
of the solar vortex, reckoning from the sun to the orbit of Neptune, the
density of the air at that extremity of the tube, would be greater than
the density of a fluid formed by the compression of the ocean into one
single drop. For the centrifugal force of the vortex at 2,300,000 miles
from the centre of the sun, is equal to gravity at the surface of the
earth, and taking the mean centrifugal force of the whole vortex as
one-millionth of this last force; so that at 3,500,000 miles from the
surface of the sun, the density of the air in the tube (supposing it
obstructed at that distance) would be double the density of the
attenuated air in the reservoir. And the air at the extremity of the
tube reaching to the orbit of Neptune, would be as much denser than the
air we breathe, as a number expressed by 273 with 239 ciphers annexed,
is greater than unity. This is on the supposition of infinite
compressibility. Now, in the solar vortex there is no physical barrier
to oppose the passage of the ether from the centre to the circumference,
and the density of the ethereal ocean must be considered uniform, except
in the interior of the stellar vortices, where it will be rarefied; and
the rarefaction will depend on the centrifugal force and the length of
the axis of the vortex. If this axis be very long, and the centrifugal
velocity very great, the polar influx will not be sufficient, and the
central parts will be rarefied. We see, therefore, no reason why the
density of the ether may not be three tim