The circles of the instrument are of aluminum, attached to the
shafts by means of wooden clamps. They were nicely graduated by a
home-made dividing engine of very simple construction, and the
figures were engraved with a pantograph. The reading is indicated
by a cut on a small aluminum plate attached to a pointer. The hour
circle is divided into 24 parts and subdivided to every four
minutes. The figures are arranged so that when the instrument is
set up, the number of hours increases while the pointer travels
oppositely to the stars. The declination circle is graduated from
zero to 90 deg. in each direction from two points 180 deg. apart.
It is, adjusted to read zero when the pointer and two axes are
mutually perpendicular as shown in the picture.
To adjust the instrument it is set up on the iron pipe and the
pointer directed to some distant object. All set screws, excepting
those on the declination axis, are tightened. Then the pointer is
carefully turned through 180 deg. and if it is not again directed
to the same point, it is not perpendicular to the declination
axis. When properly set it will describe a great circle.
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