Middle size quadrant

In order to accomplish his purpose of surverying the whole nation of Japan and to measure the distance of 1 degree latitude, Tadataka Ino needed to make accurate astronomical observations throughout the country. The quadrant was one of the surverying equipments used to measure the position of the stars. It was made with reference to the Reidaigishoushi (1674) under the order of master Shigetomi Hazama. There were two quadrants: the large-size quadrant measuring 6 shaku ( or approximately 180 cm) in radius and the middle-size quadrant measuring 3.8 shaku ( or approximately 115 cm) in radius. The middle-size quadrant was used for the nationwide surverying project.