Page:EB1911 - Volume 02.djvu/841

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Plate.
ASTROLABE


Britannica Astrolabe - Persian Astrolabe c.1712.jpg
Fig. 1. — PERSIAN ASTROLABE (c.1712) INSCRIBED IN ARABIC.
Front, showing the Rete or Spider, a network of star pointers. Beneath the Rete, in a hollow, are four thin brass discs, called Tables or Climates, engraved with projections of the sphere for different latitudes. Back, showing graduations, parallelogram for measuring heights, and other tables, together with the Rule with sights (A) held by a moveable pin (B), known as the Horse or Wedge.