ow come to be applied.

As regards the Moon itself during the continuance of the total phase,
all that need be said is that our satellite usually exhibits a disc
which is simply black; but on occasions observers have called it purple
or purplish. Although during totality the Moon is illuminated by a full
allowance of Earth-shine (light reflected by the Earth into space), yet
from all accounts this is always insufficient to reveal any traces of
the irregularities of mountains and valleys, etc., which exist on the
Moon.

When during totality any of the brighter planets, such as Mercury,
Venus, Mars, Jupiter, or Saturn, happen to be in the vicinity of the Sun
they are generally recognised; but the stars seen are usually very few,
and they are only very bright ones of the 1st or 2nd magnitudes. Perhaps
an explanation of the paucity of stars noticed is to be found in the
fact that the minds of observers are usually too much concentrated on
the Sun and Moon for any thought to be given to other things or other
parts of the sky.

Perhaps this is a convenient place in which to recall the fact that
there has been much controversy in the astronomical world during the
last 50 years as to whether there exist any undiscovered planets
revolving round the Sun within the orbit of Mercury. Whilst there is
some evidence, though slight, that one or more such planets have been
seen, opponents of the idea base their scepticism on the fact that with
so many total eclipses as there have been since 1859 (when Lescarbault
claimed to have found a planet which has been called "Vulcan"), no
certain proof has been obtained of the existence of such a planet; and
what better occasion for finding one (if one exists of any size) than
the darkness of a total solar eclipse? At present it must be confessed
that the sceptics have the best of it.

THE CORONA.

We have now to consider what I have already called the central feature
of every total eclipse. It was long ago compared to the nimbus often
placed by painters around the heads of the Virgin Mary and other saints
of old; and as conveying a rough general idea the comparison may still
stand. It has been suggested that not a bad idea of it may be obtained
by looking at a Full Moon through a wire-gauze window-screen. The Corona
comes into view a short time (usually to be measured by seconds) before
the total extinction of the Sun's rays, lasts during totality and
endure