(FIG. 3.)
In this mounting I have seen little or no alteration needful, except
that the tube is now made to balance so that the eye-tube can be
reached for objects in the zenith without the observer having to
elevate himself, and the elevating rod can be clamped without the
lever, the legs of the stand are more curved and have more spread in
them.
This “Alt-Azimuth” stand has met with much approval; and where
portability is of consideration and the observer has to set up and
remove the entire instrument after every night’s work, this, or the
Angle-Block stand, will be found the most convenient, more so than
an equatorial in any form. There is much less weight to remove, and
being in three convenient parts is more readily put together and
separated in the dark. If the stand and trunnions can be left in the
open air a very small covering will serve to protect them, and then
the tube alone has to be removed. The equatorial cannot be too
highly recommended where it can be a fixture and undisturbed, as
when once got into proper adjustments its advantages can then be
realised, but not unless it is a permanent fixture. The circles of a
portable equatorial can only be used for very rough reading, and
consequently the adjustments are never in order, and the readings
are of very limited use indeed.