The description and use of the globes and the orrery: To which is prefix'd, by way of introduction, a brief account of the solar systemHarris, Joseph
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The description and use of the globes and the orrery: To which is prefix'd, by way of introduction, a brief account of the solar system
Harris, Joseph
Astronomical models; Globes
The distance betwixt two Stars, or the number of degrees contained
betwixt them, may be found by laying the quadrant of altitude over each
of them, and counting the number of degrees intercepted; after the same
manner as we found the distance betwixt two places on the _Terrestrial_
Globe, in _Prob._ VII.
PROB. XXXVI. _The Latitude of the Place, the
Day of the Month, and the Hour being given; to
find what Stars are then rising or setting, what
Stars are culminating, or on the meridian, and
the Altitude and Azimuth of any Star above the
Horizon; and also how to distinguish the Stars in
the Heavens one from the other, and to know them by
their proper Names._
Having rectified the globe for the latitude, the zenith, and the Sun’s
place, turn the globe about until the index points to the given hour,
the globe being kept in this position.
All those Stars that are in (Eastern/Western)
side of the horizon, are then (Rising/Setting).
All those Stars that are under the meridian, are then culminating. And
if the quadrant of altitude be laid over the center of any particular
Star, it will show that Star’s altitude at that time; and where it cuts
the horizon, will be the Star’s azimuth from the North or South part of
the meridian.
The globe being kept in the same elevation, and from turning round its
axis, move the wooden frame about until the North and South points of
the horizon lie exactly in the meridian; then right lines imagined to
pass from the center thro’ each Star upon the surface of the globe,
will point out the real Star in the heavens, which those on the globe
are made to represent. And if you are by the side of some wall whose
bearing you know, lay the quadrant of altitude to that bearing in the
horizon, and it will cut all those Stars which at that very time are
to be seen in the same direction, or close by the side of the said
wall. Thus knowing some of the remarkable Stars in any part of the
heavens, the neighbouring Stars may be distinguished by observing their
situations with respect to those that are already known, and comparing
them with the Stars drawn upon the globe.
Public-domain text, read in full here on John Shaqi.
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