Museo Galileo
Virtual Museum
Tychonic scale

In the scale of degrees, denotes the division used to measure the minutes of each degree. If, for example, we want to divide the degree into four minutes, the radiocentric lines indicating the 360° along the circumference will be intersected by four equidistant concentric circles. The four minutes will be identified by the intersections of these circles with the diagonal lines plotted between two degrees. The scale is named after Tycho Brahe (1546-1601), but was probably invented by the Jewish astronomer Levi ben Gerson (1288-1344).