and we pass over
the border into Corvus, and go at once to its chief attraction, the star
delta. The components of this beautiful double are of magnitudes three
and eight; distance 24", p. 211 deg.; colors yellow and purple.

The night being dark and clear, we take the five-inch and turn it on the
nebula 3128, which the map shows just under the border of Corvus in the
edge of Hydra. Herschel believed he had resolved this into stars. It is
a faint object and small, not exceeding one eighth of the moon's
diameter.

Farther east in Hydra, as indicated near the left-hand edge of map No.
8, is a somewhat remarkable variable, R Hydrae. This star occasionally
reaches magnitude three and a half, while at minimum it is not much
above the tenth magnitude. Its period is about four hundred and
twenty-five days.

[Illustration: MAP NO. 9.]

While we have been examining these comparatively barren regions, glad to
find one or two colored doubles to relieve the monotony of the search, a
glittering white star has frequently drawn our eyes eastward and upward.
It is Spica, the great gem of Virgo, and, yielding to its attraction, we
now enter the richer constellation over which it presides (map No. 9).
Except for its beauty, which every one must admire, Spica, or alpha
Virginis, has no special claim upon our attention. Some evidence has
been obtained that, like beta Aurigae and Capella, it revolves with an
invisible companion of great mass in an orbit only six million miles in
diameter. Spica's spectrum resembles that of Sirius. The faint star
which our larger apertures show about 6' northeast of Spica is of the
tenth magnitude.

Sweeping westward, we come upon Sigma 1669, a pretty little double with
nearly equal components of about the sixth magnitude, distance 5.6", p.
124 deg.. But our interest is not fully aroused until we reach gamma, a star
with a history. The components of this celebrated binary are both
nearly of the third magnitude, distance about 5.8", p. 150 deg.. They
revolve around their common center in something less than two hundred
years. According to some authorities, the period is one hundred and
seventy years, but it is not yet certainly ascertained. It was noticed
about the beginning of the seventeenth century that gamma Virginis was
double. In 1836 the stars were so close together that no telescope then
in existence was able to separate them, although it is said that the
disk into which they had merged was elo