lavas. It is possible that these fragments of iron and stone which
constitute the meteorites have been thrown into the planetary spaces
by the volcanic eruption of our own and other planets. If hurled forth
with a sufficient energy, the fragments would escape from the control
of the attraction of the sphere whence they came, and would become
independent wanderers in space, moving around the sun in varied orbits
until they were again drawn in by some of the greater planets.

As they come to us these meteorites often break up in the atmosphere,
the bits being scattered sometimes over a wide area of country. Thus,
in the case of the Cocke County meteorite of Tennessee, one of the
iron species, the fragments, perhaps thousands in number, which came
from the explosion of the body were scattered over an area of some
thousand square miles. When they reach the surface in their natural
form, these meteors always have a curious wasted and indented
appearance, which makes it seem likely that they have been subject to
frequent collisions in their journeys after they were formed by some
violent rending action.

In some apparent kinship with the meteorites may be classed the
comets. The peculiarity of these bodies is that they appear in most
cases to be more or less completely vaporous. Rushing down from the
depths of the heavens, these bodies commonly appear as faintly
shining, cloudlike masses. As they move in toward the sun long trails
of vapour stream back from the somewhat consolidated head. Swinging
around that centre, they journey again into the outer realm. As they
retreat, their tail-like streamers appear to gather again upon their
centres, and when they fade from view they are again consolidated. In
some cases it has been suspected that a part at least of the cometary
mass was solid. The evidence goes to show, however, that the matter is