Radius mathematicus Joachima Stegmanna

Joachim Stegmann the elder (1595–1633), Brandenburg born theologian of the Polish Brethren, was also a mathematician. In this area of his activity, he published a textbook for the Unitarian school in Raków, Institutionum Mathematicarum Libri Duo (Two Books of Mathematical Sciences, Raków 1630), and two works describing multifunctional surveying devices: Circinus Quadrantarius (Quadrant Compass, Berlin 1624) and Radius Mathematicus (Mathematical Walking Stick, Berlin 1626). This paper deals with Stegmann’s Radius Mathematicus, which is a description, or rather a manual, of a walking stick of hexagonal section. Each of its sides was engraved with scales of various surveying devices. There were a cylinder sundial, a scale of quadrant for determining the altitude of Sun, a cross staff, a scala altimetra for determining the height of an object basing on the length of its shadow, a caliber gauge for determining the weight of cannonballs, a length of an ell and a gauging rod for surveying barrels. Some surveys had to be conducted with a separate gnomon. The stick was probably about 130 cm long and the gnomon was about 30 cm long. The paper is followed by a reproduction of Radius Mathematicus from the Gdańsk Library of the Polish Academy of Sciences (call number Sa 1 8° adl. 11) and its Polish translation.