Fahie, J. J. (John Joseph), 1846-1934 · London, J. Murray · leaf 67
is now called the Sector,and is to be found in most cases of mathematicalinstruments. It consists of two straight rulersconnected by a joint so that they can be set toany required angle. On one face are four pairsof lines. Arithmetical lines, which serve for the division of lines, the solution of… … ■<, ^ i6io) GEOMETRICAL COMPASS 43 Metallic lines, for finding the proportionalweights of metals, and other substances, for trans-forming a given body into one of another materialand of a given weight. On the other side of the instrument are : Polygraphic lines, for describing regularpolygons, and…
