fect the barometer at certain hours every day,) give that peculiarity
of form in certain positions of the planet in its orbit. Justice to Sir
Wm. Herschel requires that _his_ observations shall not be attributed to
optical illusions. This view, however, which may be true in the case of
Saturn, would be absurd when applied to the earth, as has been done
within the present century. From these considerations, it is at least
possible, that the density of Saturn may be very little less, or even
greater than the density of Uranus, and be in harmony with the law of
distances.

It is now apparently satisfactorily determined, that Neptune is denser
than Uranus, and the law being changed, we must look for transneptunean
planets at distances corresponding with the new law of arrangement. But
there are other modifying causes which have an influence in fixing the
precise position of equilibrium of a planet. Each planet of the system
possessing rotation, is surrounded by an ethereal vortex, and each
vortex has its own radial stream, the force of which in opposing the
radial stream of the sun, depends on the diameter and density of the
planet, on the velocity of rotation, on the inclination of its axis, and
on the density of the ether at each particular vortex; but the numerical
verification of the position of each planet with the forces we have
mentioned, cannot be made in the present state of the question. There is
one fact worthy of note, as bearing on the theory of vortices in
connection with the rotation of the planets, viz.: that observation has
determined that the axial rotation and sidereal revolution of the
secondaries, are identical; thus showing that they are without vortices,
and are motionless relative to the ether of the vortex to which they
belong. We may also advert to the theory of Doctor Olbers, that the
asteroidal group, are the fragments of a larger planet which once
filled the vacancy between Mars and Jupiter. Although this idea is not
generally received, it is gathering strength every year by the discovery
of other _fragments_, whose number now amounts to twenty-six. If the
idea be just, our theory offers an explanation of the great differences
observable in the mean distances of these bodies, and which would
otherwise form a strong objection against the hypothesis. For if these
little planets be fragments, there will be differences of density
according as they belonged to the central or superficial parts of the