Inventory no. 45366 - Former Display Label
German ASTRONOMICAL COMPENDIUM
16th century
Gilt brass, silver, etc. Unsigned and undated.
In the form of a book with clasps. Includes:
1a. A geographical astrolabe, consisting of an hour-scale within which can rotate a stereographic projection, on the plane of the Equator, of the Earth from the N. pole to the Tropic of Capricorn, showing outlines of the continents and engraved with the names of various countries and regions. Such a plate is, in fact, an ordinary plate for latitude 90° (in which almucantars coincide with declination circles and the azimuths with the hour-lines) to which have been added certain cartographical features. Over this plate is a rete, consisting of the ecliptic circle and three stars only, and an index, engraved with a latitude scale. A geographical astrolabe was useful for the resolution of certain problems relating to local time in various places of the Earth.
1b. A map of France (and parts of Italy and Switzerland), showing the positions of over a hundred towns, engraved within a circle showing sixteen of the points of the compass. In the centre is pivoted an index-arm, bearing a cursor to which a second index-arm is pivoted (about its centre). This enables the bearings of various towns relative to each other to be determined.
2. A horizontal string-gnomon dial. Under the gnomon is a compass set in a plate engraved with a compass-rose. Above are three loose silver plates, engraved on each side with hour-lines. These are marked for use in latitudes 38°-55°, each side of a plate serving for three consecutive latitudes. These plates have a central hole to reveal the compass, and are placed above the wind-rose so that the plate for the appropriate latitude is on top. There is a detachable gnomon-support (a replacement - the original would have had provision for latitude adjustment) which plugs into a slot. The knotted end of the string-gnomon projects above a small tube by the compass, the string-gnomon itself being wound round a small drum, containing a spring, below the compass-plate. When the gnomon-support has been placed in the slot, the knotted end of the gnomon is pulled until it can be inserted in a notch in the gnomon. As the gnomon is pulled, the spring in the drum is further wound up keeping the gnomon taut while in use, whatever latitude it is set to. On releasing the gnomon, the spring rewinds it on the drum.
3a. A lunar volvelle and aspectarium.
3b. A 'Geminus' or Roias dial.
The inscriptions are in French and Latin. This instrument was probably made by Christoph Schissler the Elder, of Augsburg, and has many of the characteristics of his work, especially the decorative engraving, the design of the wind-rose and the map, and the spring-wound drum for the string-gnomon.
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Billmeir Collection