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— Mobile Sun-Dials: Compass Sun-Dial Type 3 (Box) —

These instruments measure the hour angle. When the box is opened, a thread functions as pointer. The opened box is to be aligned until the compass points to north. The shadow on the vertical scale shows the True Local Time for 50° north, the one on the horizontal one that for 40° south. The original was built in 1745 with the inscription Je suis pour tous (I am for everyone).

Compass 3
 
  © 2004 - 2017 by Horo Wernli.