pal star varies
from magnitude three and seven tenths down to magnitude four and a half
in a period of a little more than ten days.

[Illustration: WONDERFUL NEBULA IN GEMINI (1532).]

With the four-or five-inch we get a very pretty sight in delta, which
appears split into a yellow and a purple star, magnitudes three and
eight, distance 7", p. 206 deg..

Near delta, toward the east, lies one of the strangest of all the
nebulae. (See the figures 1532 on the map.) Our telescopes will show it
to us only as a minute star surrounded with a nebulous atmosphere, but
its appearance with instruments of the first magnitude is so
astonishing and at the same time so beautiful that I can not refrain
from giving a brief description of it as I saw it in 1893 with the great
Lick telescope. In the center glittered the star, and spread evenly
around it was a circular nebulous disk, pale yet sparkling and
conspicuous. This disk was sharply bordered by a narrow _black_ ring,
and outside the ring the luminous haze of the nebula again appeared,
gradually fading toward the edge to invisibility. The accompanying cut,
which exaggerates the brightness of the nebula as compared with the
star, gives but a faint idea of this most singular object. If its
peculiarities were within the reach of ordinary telescopes, there are
few scenes in the heavens that would be deemed equally admirable.

In the star eta we have another long-period variable, which is also a
double star; unfortunately the companion, being of only the tenth
magnitude and distant less than 1" from its third-magnitude primary, is
beyond the reach of our telescopes. But eta points the way to one of the
finest star clusters in the sky, marked 1360 on the map. The naked eye
perceives that there is something remarkable in that place, and the
opera glass faintly reveals its distant splendors, but the telescope
fairly carries us into its presence. Its stars are innumerable, varying
from the ninth magnitude downward to the last limit of visibility, and
presenting a wonderful array of curves which are highly interesting from
the point of view of the nebular origin of such clusters. Looking
backward in time, with that theory to guide us, we can see spiral lines
of nebulous mist occupying the space that now glitters with interlacing
rows of stars. It is certainly difficult to understand how such lines of
nebula could become knotted with the nuclei of future stars, and then
gradually be absorb