History of Science Museum: Collection Database Search


Inventory no. 35171 - Former Display Label


Brass. Unsigned, but probably by Johan Motter (or Mueter); dated, "1602".

This instrument is an example of the astronomical ring as described by Gemma Frisius. It is almost identical with the astronomical ring by Johan Motter in the Royal Observatory of Belgium. Astronomical rings of this type are very rare.

As well as for time-telling by the sun, the instrument may be used by night. The declinations and names of twenty fixed stars (each with a number) are marked on the outside of the moveable meridian ring. Within the same ring is engraved a Zodiac scale on which the same stars are marked (by their numbers) at the dates when their right ascension is the same as that of the sun.

Under the equatorial ring is marked a shadow-scale whose use is the same as the shadow-square on an astrolabe i.e. determining the heights of objects by means of the length of the shadows they cast.

[F. 42]
Lewis Evans Collection.

Other narratives:

Related Objects: