Khwarizmi’s sine quadrant was a type of quadrant used by Arabic astronomer for various purposes. It was used to measure celestial angles, to tell time, and to find directions, among its many other uses. According to Wikipedia:
“The instrument is a quarter of a circle made of wood or metal (usually brass) divided on its arc side into 90 equal parts or degrees. The 90 divisions are gathered in 18 groups of five degrees each and are generally numbered both ways from the ends of the arc. That is, one set of numbers begins at the left end of the arc and goes to 90 at the right end while the other set the zero is at the right and the 90 is at the left. This double numbering enables the instrument to measure either celestial altitude or zenith distance or both simultaneously.”