ast might arise from a momentary
fluctuation in the relative intensities of the electric radiation of the
comet, and of the radial stream, owing to the probable irregularities
just alluded to. Such and kindred phenomena are utterly inexplicable,
without we adopt the theory we are advocating. One other feature, and we
will leave the subject.

From our explanation of the solar spots, we inferred the existence of
another large planet in the system. Might not the same effect be
produced by a comet? Or may there not be so many comets, whose great
elongation, combined with even a moderate mass, may render it impossible
to calculate the position of the sun with respect to the central axis of
the vortex,--always considering this last as the axis of equilibrium? In
a general way, we might say that the very number of comets in all
directions and all distances, would tend to neutralize each other's
effects; but we are not under this necessity. A comet, moving in a
parabola, does not belong to the system or to the rotating vortex; and
the periodic comets, if of gaseous elements, (as seems so probable,)
must, from the size of their nuclei, which the theory considers the only
part constituting their mass, have far less mass than the very smallest
of the asteroids, and consequently could have very little effect on the
mechanical balance of the vortex, even if elongated as far as the orbit
of Neptune. Did we know the influence of cold in limiting the
expansibility of the elementary gases, we might approximately determine
the mass of a comet, from the size of its nucleus; but this is a problem
that has never yet been solved; and astronomers ought to avail
themselves of every indication which promises to realize this great
desideratum. The grand comet of 1556 is now probably approaching, and,
from recent investigations, it appears that it will arrive at its
perihelion in 1858,--subject to an error either way of about two years.
An opportunity may thus be presented of determining the mass of one of
the largest comets on record, which may not again occur. This arises
from the possible appulse of the comet to the planet Pallas, whose mass,
being so small, would more sensibly be disturbed by such an appulse than
the earth. As the inclinations and ascending nodes of the two orbits
approximately coincide, and as Pallas will be near the comet's path, on
the approach of the latter to the sun, at the beginning of the year
1857, should the comet b