Object Name: planispheric astrolabe
Dimensions: 19.6 x 14.9 x 3.1 cm (7 11/16 x 5 7/8 x 1 1/4 in.)
Description: This planispheric astrolabe is made of brass and has projections for 7 latitudes.
The front rim of the mater is divided. In the well of the mater is a stereographic projection for a given latitude and lines for unequal hours. The back side of the mater has a crack with a repair. The limb is divided into 1° units. There are concentric scales for the zodiacal and civil calendars, and these are divided into units of 1° and days. The upper right and upper left quadrants are plain except for a crescent moon shape. The lower right quadrant has a shadow square. The lower left quadrant is plain.
The rete has 27 stars. The zodiacal scale on the ecliptic is divided every 3°. The reverse side shows construction marks from a prior attempt.
The rule is plain.
The alidade has pin-hole sights.
The bolt has a flower head on the top and "pleated hat" on the other end. The horse is shaped like the figure of a horse.
There are three typmans. Each is notched. There are two stereographic projections on each tympan, giving a total of six. All are for low latitudes. All show unequal hours. One has the astrological houses marked, and has inlaid silver prayer lines.
Curatorial Remarks: XRF analysis of the metals was done by Katherine Eremin and Sara Schechner in August 2007.
On Gillingham inventory, April 5, 1949, typescript p. 11: "Astrolabe. Arabian, 5, 3/4 inches diam. with horse pin. Mercator, Paris, 1930. 8,000 fcs. 350."
Primary Sources: Harrold Edgar Gillingham Papers, Collection of Historical Scientific Instruments, Harvard University.
Provenance: Mercator (Gertrude Stein), Paris, 1930; Harrold E. Gillingham, Philadelphia, 1930; David P. Wheatland, Topsfield, MA, 1949; gift to CHSI, c. 1985.