Repeating Circle

1815 - Georg Reichenbach, Munich / Brass, silver / Diameter: 32 cm

The repeating circle is so called because it can ‘repeat’ several observations of the angular distance of two objects and of their zenithal distance. In fact, for each observation, it is possible to obtain increasing integer multiples of the unknown angle, thus minimising reading errors and obtaining more precise measurements.
 
The instrument is made of a circle of one Parisian foot in diameter (32.5 cm). The scale, divided into five-minute segments, is engraved on a silver strip. Two telescopes run independently along the limb, on or under the circle; they can also turn together with it. The instrument is supported by a brass tripod, with two counterweights and a horizontal circle for measuring the azimuth. On the limb is engraved: “Reichenbach Utzschneider u Liebherr in München”.
 
This instrument was purchased in 1815 and used by Giovanni Santini to determine the geographic latitude of the Observatory of Padova.

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