ith the force, we will
reduce them by making the first numbers equal.

Distances. Diameters. The 2.5th power Reduced
of the Distances. Diameters.
1.4617 79.4 2.58 2.58
1.3217 64.8 2.10 2.10
0.9668 29.8 0.92 0.97
0.8473 19.9 0.66 0.65
0.7285 11.3 0.45 0.37
0.5419 3.1 0.21 0.10

This is a very close approximation, when we consider the difficulty of
micrometric measurement, and the fact, that as the comet gets nearer to
the sun, as at the last date of the table, the diameter is more than
proportionally diminished by the fainter nebulosity becoming invisible.
But, there may be a reality in the discrepancy apparent at the last
date, as the comet was then very near the plane of the ecliptic, and
was, consequently, exposed to the more violent action of the radial
stream.

To attempt to explain the _modus agendi_ is, perhaps, premature. Our
principal aim is to pioneer the way into the labyrinth, and it is
sufficient to connect this seeming anomaly with the same general law we
have deduced from other phenomena. Still, an explanation may be given in
strict accordance with the general principles of the theory.

Admitting the _nucleus_ of a comet to be gaseous, there is no difficulty
about the solution. According to Sir John Herschel, "stars of the
smallest magnitude remain distinctly visible, though covered by what
appears the densest portion of their substances; and since it is an
observed fact, that the large comets which have presented the appearance
of a nucleus, have yet exhibited no phases, though we cannot doubt that
they shine by the reflected solar light, it follows that even these can
only be regarded as great masses of thin vapor." That comets shine
solely by reflected solar light, is a position that we shall presently
question; but that they are masses of vapor is too evident to dispute.
According to the same authority quoted above, "If the earth were reduced
to the one thousandth part of its actual mass, its coercive power over
the atmosphere would be diminished in the same proportion, and in
consequence the latter would expand to a thousand times its actual
_bulk_." If this were so, and comets composed of the elementary gases,
some of them would have ve