This arrangement seems to me to be in many respects defective, however.

The slow movement in altitude is not uniform, but varies in effect according to the elevation of the object observed.

It is also limited in range; and quite a little series of operations has to be gone through when it is required to direct the telescope towards a new quarter of the heavens.

However expert the observer may become by practice in effecting these operations, they necessarily take up some time (performed as they must be in the dark, or by the light of a small lantern), and during this time it often happens that a favourable opportunity for observation is lost.
These disadvantages are obviated when the telescope is mounted in such a manner as is exhibited in fig.

8, which represents a telescope of my own construction.