It is evident from a study of the
picture that the position of the small pointer which indicates the
reading on the hour circle is not independent of the way in which
the tripod or pipe is set up. It would then be useless to adjust
it carefully to zero when the pointer cuts the "zenith" as is done
with a large equatorial. Instead, the adjustment is made by
setting the clock or watch which is part of the outfit. The
pointer is directed to Alpha, Cassiopiae, and the hour reading
subtracted from 24 hours (the approximate right ascension of the
star) gives the time which the clock should be set to indicate.
All of these settings should require not more than five minutes.
To find a star in the heavens, look up its declination and right
ascension in an atlas. Set the declination circle to its reading.
Subtract the clock time from the right ascension (plus 24 if
necessary) and set the hour circle to the result. The star will
then be seen on the tip of the pointer.
To locate a known star on the map, turn the pointer to the star.
Declination is read directly. Add the clock time to the hour
reading to get right ascension.
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