Hence (assuming the existence of a dark secondary) we must suppose that either it travels in a resisting medium 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.