Lot 172

German, 55 x 95 x 10 mm, 99 g, circa 1580
An important ivory Regiomontanus sun dial with original leather box
Case: ivory, silver.
A brilliant invention dating from the year 1476, by Johannes Müller known as Regiomontanus, the famous astronomer and mathematician from Königsberg in Lower Franconia. The travel sundial was suited for latitudes from 25 to 66°. This ivory sundial is fitted with a small, articulated silver arm with a fine string; the string has a silver bead as a weight and a second bead that moves. On the side are two holes for sighting. To read the time, the plumb line and the moving bead are set on the date and the geographic latitude. When the sunlight falls through the two holes and the watch is aligned accurately, the bead will show the correct local time. The silver lid conceals a tiny compartment for accessories and on the back a table with the signs of the Zodiac is shown.
Even the extensive collection of sundials in the National Maritime Museum in Greenwich only owns two similar examples.

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