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HOW TO WORK WITH THE TELESCOPE. 
PART II. 
THE ALT-AZIMUTH. THE EQUATORIAL. PRACTICAL HINTS. 
OBJECTS FOR OBSERVATION. 
By RICHARD A. PROCTOR, B.A., F.R.A.S., 
Author of “ Saturn and its System .” 
T HE best known, and, in some respects, tbe simplest method 
of mounting a telescope for general observation is that 
called the altitude and azimuth mounting. In this method 
the telescope is pointed towards an object by two motions, — 
one giving the tube the required altitude (or elevation), the 
other giving it the required azimuth (or direction as respects 
the compass-points). 
For small alt-azimuths the ordinary pillar-and-claw stand 
is sufficiently steady. For larger instruments other arrange- 
ments are needed, both to give the telescope steadiness, and 
to supply slow movements in altitude and azimuth. The 
arrangement of sliding-tubes and rack- work commonly adopted 
is defective in many respects. 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 sky. However expert the observer may become by prac- 
tice 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 the manner shown in Plate XXII., fig. 1, which re- 
presents a telescope of my own construction. The slow move- 
ment in altitude is given by rotating the rod h e , the endless 
screw in which turns the small wheel at h, whose axle in turn bears 
a pinion-wheel working in the teeth of the quadrant a. The slow 
