n divided according to their brilliancy into sixteen classes or
magnitudes. The fifteen brightest stars are said to be of the first
magnitude, the fifty next of the second, and so on to the sixth, which
comprises the faintest stars visible to the unassisted eye. The
brightest star of all visible in our latitude is the dogstar, which
gives four times as much light as any other. In every age of the world
there have been learned men interested enough in the stars to make
catalogues of them, giving their magnitudes and their positions."

"I think they must have been very slow and stupid follows," said Gus,
"or they would have found something better to do."

At this the Professor laughed.

[Illustration: THE GREAT EQUATORIAL, UNITED STATES NATIONAL
OBSERVATORY.]

"I think, Gus, you are hungry, and have your mind on mutton-chops. I
shall not talk to you any more this morning; but, after lunch, if you
will look in one of the great books in papa's library, which he will
point out, you will find pictures of all the great telescopes in the
world. The best one in our own country is that at the United States
National Observatory at Washington. Without the aid of these wonderful
instruments we should never have learned much about the stars."

THE HISTORY OF PHOTOGEN AND NYCTERIS.

A Day and Night Maehrchen.

By GEORGE MACDONALD.

I.--WATHO.

There was once a witch who desired to know everything. But the wiser a
witch is, the harder she knocks her head against the wall when she comes
to it. Her name was Watho, and she had a wolf in her mind. She cared for
nothing in itself--only for knowing it. She was not naturally cruel, but
the wolf had made her cruel.

She was tall and graceful, with a white skin, red hair, and black eyes,
which had a red fire in them. She was straight and strong, but now and
then would fall bent together, shudder, and sit for a moment with her
head turned over her shoulder, as if the wolf had got out of her mind on
to her back.

II.--AURORA.

This witch got two ladies to visit her. One of them belonged to the
court, and her husband had been sent on a far and difficult embassy. The
other was a young widow whose husband had lately died, and who had since
lost her sight. Watho lodged them in different parts of her castle, and
they did not know of each other's existence.

The castle stood on the side of a hill sloping gently down into a narrow
valley, in which was a river, with a pebbly ch