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 223
6. 2 Dycks Catalogue, 1892. ■- Morin, Les Appareils dIntegration, p. 6i, 1913. 13 194 SECTION G Type II.—Planimeters with an Arm of Constant Length The construction of this type is based on the following theory :— Consider two areas S, S, bounded by the closed contours C, C. Take a point A on C and… … Fig. 3. If in this motion AB be any position of the arm, and AB a consecutiveposition, the elementary area ABBA swept out by AB=/^ssin a+ \l2d<bwhere ds is the arc BB of C, a is the angle between AB and the tangent atB to C, and dcp is the angle turned through by AB. This is seen at onceby…
