An introduction to astronomy: designed as a text-book for the use of students in college. By Denison Olmsted ...

ARTIFICIAL GLOBES. 23
62. An artificial globe is encompassed from north to south
by a strong brass ring, to represent the meridian of the place.
This ring is made fast to the two poles, and thus supports the
globe, while it is itself supported in a vertical position by
means of a frame, the ring being usually let into a socket in
which it may be easily slid, so, as to give ally required elevation to the pole. The brass meridiaf is graduated each way
from the equator to the pole 90~, to measure degrees of latitude
or declination, according as the distance from the equator
refers to a point on the earth or in the heavens. The horizon
is represented by a broad zone, made broad for the convenience
of carrying on it a circle of azimuth, another of amplitude, and
a wide space on which are delineated the signs of the ecliptic,
and the sun's place for every day in the year; not because
these points have any special connection with the horizon, but
because this broad surface furnishes a convenient place for
recording them.
63. IIlour Circles are represented on the terrestrial globc
by great circles drawn through the pole of the equator; but,
on the celestial globe, corresponding circles pass through the
poles of the ecliptic, constituting circles of celestial latitucle
(Art. 37), while the brass meridian, being a secondary to the
equinoctial, becomes an hour circle of any star which, by
turning the globe, is brought under it.
64. The:zotur Index is a small circle described around the
pole of the equator, on which are marked the hours of the day.
As this circle turns along with the globe, it makes a complete
revolution in the same time with the equator; or, for any less
period, the same number of degrees of this circle and of the
equator pass under the meridian. Hence the hour index
measures arcs of right ascension. (Art. 37.)
65. The Quadrant of Altitude is a flexible strip of brass,
graduated into ninety equal parts, corresponding in length to
degrees on the globe, so that when applied to the globe a:id
bent so as closely to fit its surface, it measures the ari,gular
distance between any two points. When the zero, or the
point where the graduation begins, is laid on the pole of any