Turkish Horary Quadrant

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This undated Turkish quadrant is made of yellow paper lacquered to a wooden base. Lines, script, and numerals are marked in red and black pigment. All markings are in Arabic. The edges are painted red. One edge is indented, serving to sight the sun. A hole near the square corner would hold a plumb bob.
One side of the quadrant contains scales for declination and right ascension, azimuth arcs, an ecliptic arc, and hour arcs. The circumference is calibrated from zero to ninety by single degree in groups of five.
The reverse contains a grid for reading off sines and cosines. It also has two semicircles at right angles to each other, an arc connecting the twenty-fourth mark on each axis, and two red lines sloping up to the right. Numerous dots are at points of intersection on the grid. Both axes of the grid are marked in groups of five units. The circumference on this face is also calibrated from zero to ninety degrees by degree in groups of five.
A similar horary quadrant is at the Museum of the History of Science of Oxford University. , inventory number 35612 (accessed 29 February 2016).
Glen van Brummelen, The Mathematics of the Heavens and the Earth: The Early History of Trigonometry, Princeton and Oxford: Princeton University Press, 2009, esp. pp. 209-211.
A similar instrument in the collections of the Greenwich Maritime Museum is described in Hester Higton, Sundials at Greenwich, Oxford: Oxford university Press, 2002, esp. pp. 368-369.
Currently not on view
place made
Physical Description
wood (base material)
paper (scales material)
overall: 1.6 cm x 14 cm x 14.1 cm; 5/8 in x 5 1/2 in x 5 9/16 in
ID Number
catalog number
accession number
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Data Source
National Museum of American History, Kenneth E. Behring Center


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