GB573095A - Improvements in or relating to calculators for the solution of triangles - Google Patents

Abstract

573,095. Trigonometrical calculators. BATES, E. Nov. 5, 1943, No. 18423. [Class 97 (iii)] [Also in Group XIX] A calculator for the solution of triangles comprises a rectangular base 1 marked with a datum line 2 spaced from each of its longitudinal edges and with graduations 3, 25, an arm 5 having graduations 6 and pivoted to the base by a pivot 4 to turn about an axis intersecting the datum line 2, a semi-circular protractor scale 8 situated on the base 1 about the said axis, a cursor 9 with an aperture 17 slidably engaged with the opposite longitudinal edges of the base 1 and carrying a pivot 10 which travels along the datum line 2 on movement of the cursor, a second graduated arm 13 mounted on the pivot 10 and a second semi-circular protractor scale 11 about the pivot 10 and disposed on the cursor. The arms 5, 13 may be locked in any position by the nuts 23 and each is marked with a line 26, 27 for alignment with the lines 24, 28 for right-angled positioning with respect to the base 1. When required a third protractor scale 18 may be slidably mounted on the arm 5 by lips 22 and extensions 270 may be fitted into slots 260 in the arms. In use the datum line 2 and adjustable arms 5, 13 are superposed on the triangle and detail read off.