Universal circle, Strasbourg Observatory, 1876.
© Science Museum / Science & Society Picture Library
Photograph of a universal circle that made by the German instrument makers of F W Breithaupt & Son of Kassel. A portable astronomical instrument it was used to measure the position of the stars, planets, Moon and Sun in the heavens. Unlike a transit instrument, which can only be used in the north-south meridian, the universal circle can make measurements anywhere in the sky. The instrument shown in the photograph was supplied to the Strasbourg Observatory that was then part of Germany, but now lies in France.