's Wain, but
astronomers prefer to regard it as a portion of the constellation of the
Great Bear (Ursa Major). There are many features of interest in this
constellation, and the beginner should learn as soon as possible to
identify the seven stars which compose it. Of these the two marked
a and b, at the head of the Bear, are generally called the
"pointers." They are of special use, because they serve to guide the eye
to that most important star in the whole sky, known as the "pole star."

Fix the attention on that region in the Great Bear, which forms a sort
of rectangle, of which the stars a b g d are the corners. The next fine
night try to count how many stars are visible within that rectangle. On
a very fine night, without a moon, perhaps a dozen might be perceived,
or even more, according to the keenness of the eyesight. But when the
opera-glass is directed to the same part of the constellation an
astonishing sight is witnessed. A hundred stars can now be seen with the
greatest ease.

But the opera-glass will not show nearly all the stars in this region.
Any good telescope will reveal many hundreds too faint for the feebler
instrument. The greater the telescope the more numerous the stars: so
that seen through one of the colossal instruments the number would have
to be reckoned in thousands.

We have chosen the Great Bear because it is more generally known than
any other constellation. But the Great Bear is not exceptionally rich in
stars. To tell the number of the stars is a task which no man has
accomplished; but various estimates have been made. Our great telescopes
can probably show at least 50,000,000 stars.

The student who uses a good refracting telescope, having an object-glass
not less than three inches in diameter, will find occupation for many a
fine evening. It will greatly increase the interest of his work if he
have the charming handbook of the heavens known as Webb's "Celestial
Objects for Common Telescopes."

CHAPTER II.

THE SUN.

The vast Size of the Sun--Hotter than Melting Platinum--Is the Sun
the Source of Heat for the Earth?--The Sun is 92,900,000 miles
distant--How to realise the magnitude of this distance--Day and
Night--Luminous and Non-Luminous Bodies--Contrast between the Sun
and the Stars--The Sun a Star--Granulated Appearance of the
Sun--The Spots on the Sun--Changes in the Form of a Spot--The
Faculae--The Rotation of the Sun on its Ax