Modern instruments and methods of calculation : a handbook of the Napier Tercentenary Exhibition (1914)
Horsburg, E. M. (Ellice Martin), Napier Tercentenary Exhibition (1914 : Edinburgh, Scotalnd) · London : G. Bell · leaf 299
B :o 3o *i *• ** *u w w» * li5 ,M w°t.l5*il- /;o 11; is; i?= w> w «J_«f. »o i« *» ;,V^ Fig. 1.—Protractor for Polar Co-ordinates. … Fig. 2.—Single Parts of Protractor. The rule L is 12 inches long, and bears on the bevelled edge a suitablegraduation. It is fixed to the drawing by setting the pin p, which marksthe centre, in the socket h. The roller frame R is then connected with therule by placing the small ball pins/and/ in…
