um which is gradually
destroying its motion, or that there are other dependent orbs whose
attractions affect the period of this secondary. In the latter case the
decrease in the period will attain a limit and be followed by an
increase.
However, interesting as the subject may be, it is a digression from
telescopic work, to which we now return.
Within the confines of the second map in Plate 4 is seen the fine star
[gamma] Andromedae. At the hour of our observations it lies high up
towards E.S.E. It is seen as a double star with very moderate telescopic
power, the distance between the components being upwards of 10"; their
magnitudes 3 and 5-1/2, their colours orange and green. Perhaps there is
no more interesting double visible with low powers. The smaller star is
again double in first-class telescopes, the components being yellow and
blue according to some observers, but according to others, both green.
Below [gamma] Andromedae lie the stars [beta] and [gamma] Triangulorum,
[gamma] a fine naked-eye triple (the companions being [delta] and [eta]
Triangulorum), a fine object with a very low power. To the right is
[alpha] Triangulorum, certainly less brilliant than [beta]. Below
[alpha] are the three stars [alpha], [beta], and [gamma] Arietis, the
first an unequal and difficult double, the companion being purple, and
only just visible (under favourable circumstances) with a good 3-inch
telescope; the last an easy double, interesting as being the first ever
discovered (by Hook, in 1664), the colours of components white and grey.
Immediately below [alpha] Arietis is the star [alpha] Ceti, towards the
right of which (a little lower) is Mira, a wonderful variable. This star
has a period of 331-1/3 days; during a fortnight it appears as a star of
the 2nd magnitude,--on each side of this fortnight there is a period of
three months during one of which the star is increasing, while during
the other it is diminishing in brightness: during the remaining five
months of the period the star is invisible to the naked eye. There are
many peculiarities and changes in the variation of this star, into which
space will not permit me to enter.
Immediately above Mira is the star [alpha] Piscium at the knot of the
Fishes' connecting band. This is a fine double, the distance between the
components being about 3-1/2", their magnitudes 5 and 6, their colours
pale green and blue (see Plate 5).
Close to [gamma] Aquarii (see Frontispiece,
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