Construction and Design
The astrolabe is constructed of gilt brass, featuring a throne of simple type decorated with s-shaped scrollwork and a small disc engraved with a flower on both sides. The mater and limb are of one-piece construction. The limb is inscribed with wind directions, including SYROCCHO, LEVANTE, GRECO, TRAMONTANO, MAGISTRAL, PONENTE, and LEBECCIO. The instrument is suspended by a simple band ring and a rotating pin-type shackle.
The back contains eleven scales, including altitude, zodiacal signs, calendar, windrose, dominical letter, solar cycle, golden number, epact, perpetual calendar, and a shadow square. The instrument is signed by the maker on the back. The rete is of an ornate type containing seventeen stars marked with flamant pointers and zodiacal labels in Latin.
Evidence for this section
- “The throne is of the simple
type made of brass with s-shaped scroll work support(s) made
of brass and has a simple, band ring made of brass
and rotating pin type shackle made of brass”
- “The back contains 11 scales of the following
types:
Altitude; Zodiacal signs; Calendar; Windrose; Dominical
letter; Solar cycle; Golden number; Epact; Perpetual
calendar; Shadow square.”
Projection and Modifications
This astrolabe features a unique southern projection of the terrestrial sphere, which departs from the more common north polar projections found in other instruments of the period. This specific plate depicts the terrestrial globe from the north looking south, with the plane of projection tangent at the south pole, effectively placing Madagascar to the left of Africa and South America to the right.
In the late 17th century, the instrument underwent modifications by the Parisian maker Pierre Sevin. He added a plate calibrated for the latitude of Paris, featuring a De Rojas universal projection on the reverse side. Additionally, he supplied a new regula, cursor, and brachiolum to ensure the functional compatibility of the instrument for its new user.
Evidence for this section
- “The remarkable feature of this instrument is the southern
projection of the terrestrial sphere.”
- “The astrolabe currently has just one other plate, added
for a later owner by the late 17th-century Parisian maker
Pierre Sevin.”
Provenance and History
The astrolabe was previously part of the Chadenat collection in Paris. It was displayed at the Musée des Arts Décoratifs in 1932. J. A. Billmeir acquired the object at the Chadenat auction held at the Hôtel Drouot on 24 May 1956.
Following its acquisition, it was presented to the History of Science Museum in 1957. The modifications performed by Pierre Sevin in the 1670s or 1680s suggest the astrolabe remained in active use in a Parisian context well after its initial manufacture in 1600.
Evidence for this section
- “Billmeir bought it at the auction sale of
the Chadenat collection at the Hotel Drouot, Paris, on 24 May
1956.”
- “The
additional plate for the latitude of Paris made by Pierre
Sevin, and the case of about the same date, indicate that it
was modified for a Parisian owner in the 1670s or 1680s.”
