A European brass single-plate astrolabe, seemingly for near the 52° latitude line, the 4 7/8-inch(12.4cm.) mater with .15-inch (.35cm.) thick limb, the front divided with one scale of time, twenty four hours I-XII-I-XII, in four-minute intervals (one degree=four minutes of time), the hours labelled in Roman numeralsm the cast-brass rete cut to a simple pattern of circles with approximately sixty star-pointers, (thirty-five inside the ecliptic circle, twenty-five outside; eighteen named), parts of the framework with dots in a small circle possibly indicating further star positions, the plate engraved with the stereographicprojection for 52.G as engraved on the limb, the back engraved with the circles for the equator and tropics only, the back with degree scale divided in single degrees and numbered every ten in four quadrents, the calendar scale eccentric inside the Zodiac scale, the point of Aries at 10.5 March, with unequal hour diagram and shadow square, lacks alidade and pin, late 16th/early 17th century

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A European brass single-plate astrolabe, seemingly for near the 52° latitude line, the 4 7/8-inch(12.4cm.) mater with .15-inch (.35cm.) thick limb, the front divided with one scale of time, twenty four hours I-XII-I-XII, in four-minute intervals (one degree=four minutes of time), the hours labelled in Roman numeralsm the cast-brass rete cut to a simple pattern of circles with approximately sixty star-pointers, (thirty-five inside the ecliptic circle, twenty-five outside; eighteen named), parts of the framework with dots in a small circle possibly indicating further star positions, the plate engraved with the stereographicprojection for 52.G as engraved on the limb, the back engraved with the circles for the equator and tropics only, the back with degree scale divided in single degrees and numbered every ten in four quadrents, the calendar scale eccentric inside the Zodiac scale, the point of Aries at 10.5 March, with unequal hour diagram and shadow square, lacks alidade and pin, late 16th/early 17th century

See colour plate

Lot Essay

The latitude line 52° could indicate use in Munster, Magdeburg, Berlin or Warsaw.

A remarkable feature of this instrument is the punches used to letter and number the parts. The set of punches was not complete, consequently A is a V inverted; R is I i and C; Q is O and I; T is I with another across the top; S is c twice; X is lacking or was forgotten, consequently the X is lacking for the numbers IX, X, XI and XII. The inside of the mater is blank, but does show the marks left by the punches used on the back of the instrument.

The design of this astrolabe is that published by Johan Krabbe (1553-1616), a native of Munden, northern Germany. A wood and cardboard version dated 1583 is in the Museum of the History of Science, Oxford. It is 8¼-inches in diamater and has about seventy-nine stars on the rete. The rete pattern and the star-pointers resemble closly those in the present brass instrument. Having been printed from an engraved plate the lettering on the cardboard instrument is good, whereas the person who tried to letter the brass version was unable to produce satisfactory labelling. Krabbe published Newes Astrolabium sampt deren Nutzen und Gebrauch (Wolfenbutel, 1608) and four later editions.

A brass astrolabe by Krabbe, dated 1579, is in the Museum of the Observatory of Strasbourg, and it is illustrated in A. Danjon & A. Couder, Lunettes et Telescopes (Paris, 1935), fig. 308. This shows a well executed astrolabe of 201mm. diamater. The present is likely to be one constructed for the diagrams in Krabbe's book.

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