t that the legend is really "Isti
mirantur stellam," the missing letters being supposed to be hidden by
the building and the comet.

CHAPTER XXI

METEORS OR SHOOTING STARS

Any one who happens to gaze at the sky for a short time on a clear night
is pretty certain to be rewarded with a view of what is popularly known
as a "shooting star." Such an object, however, is not a star at all, but
has received its appellation from an analogy; for the phenomenon gives
to the inexperienced in these matters an impression as if one of the
many points of light, which glitter in the vaulted heaven, had suddenly
become loosened from its place, and was falling towards the earth. In
its passage across the sky the moving object leaves behind a trail of
light which usually lasts for a few moments. Shooting stars, or meteors,
as they are technically termed, are for the most part very small bodies,
perhaps no larger than peas or pebbles, which, dashing towards our earth
from space beyond, are heated to a white heat, and reduced to powder by
the friction resulting from their rapid passage into our atmosphere.
This they enter at various degrees of speed, in some cases so great as
45 miles a second. The speed, of course, will depend greatly upon
whether the earth and the meteors are rushing towards each other, or
whether the latter are merely overtaking the earth. In the first of
these cases the meteors will naturally collide with the atmosphere with
great force; in the other case they will plainly come into it with much
less rapidity. As has been already stated, it is from observations of
such bodies that we are enabled to estimate, though very imperfectly,
the height at which the air around our globe practically ceases, and
this height is imagined to be somewhere about 100 miles. Fortunate,
indeed, is it for us that there is a goodly layer of atmosphere over our
heads, for, were this not so, these visitors from space would strike
upon the surface of our earth night and day, and render existence still
more unendurable than many persons choose to consider it. To what a
bombardment must the moon be continually subject, destitute as she is of
such an atmospheric shield!

It is only in the moment of their dissolution that we really learn
anything about meteors, for these bodies are much too small to be seen
before they enter our atmosphere. The debris arising from their
destruction is wafted over the earth, and, settling down eventually