Page 396 - 89 history of astronomy_opt
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[1] In 1480 Martin Behaim, of Nurem-
berg, produced his astrolabe for measur-
ing the latitude, by observation of the sun,
at sea. It consisted of a graduated metal cir-
cle, suspended by a ring which was passed
over the thumb, and hung vertically. A
pointer was fixed to a pin at the centre.
This arm, called the alhidada , worked round
the graduated circle, and was pointed to the
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