shown that, if the periodic times of the planets are
approximately equal to the periodic times of the contiguous parts of the
solar vortex, the density of the ether is directly as the square roots
of the distances from the centre. As the earth is at her perihelion
about the first of January, the density of the surrounding ether is then
less than in other parts of the orbit; consequently, if we suppose that
there is a continual tendency to equilibrium, the ether of space must
press inwards, during the time between the perihelion and aphelion,
(_i.e._ from January to July,) lowering the temperature and increasing
the electrical action of those months. As the distance from the sun is
most rapidly augmenting about the first of April, and the effective
power of the sun's radiation is most rapidly increasing in May; by
combining the two we shall find, that about the first of May we shall
have considerable electrical action, and cold weather. This explains
also, in part, the prevalent tradition of certain days in May being very
cold.[26] When the earth leaves the aphelion, a reaction takes place,
being most rapid in September. There is then an _escape_ of ether from
the earth, which keeps up the temperature, and causes these months to be
sickly, from the negative electrical state of the atmosphere. In the
southern hemisphere, the effects in the same season will be reversed,
which may partly account for the greater degree of cold in that
hemisphere, and for accelerating the approach of both summer and winter,
while in the north they were both retarded.

We must now advert to another cause, which of all others is probably the
most important, at least to the other members of the solar system.

In every part of the solar vortex the ether is continually pressing
outwards. We are not now speaking of the radial stream, but of the
slower spiral motion of the ether around the axis of the vortex, whose
centrifugal force is bearing the whole body of the ether outwards, thus
rarefying the central parts, and thus giving rise to the polar influx,
from which arises the radial stream. This may be made more intelligible,
by reflecting that the polar current is comparatively dense ether, and
that the length of the axis of the vortex prevents this influx current
coming in sufficient quantities to restore an equilibrium in the density
of the medium. Yet, what does come down the poles, is distributed
rapidly along the equatorial plane, leaving th