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 227
t 1 Phil. Mag., p. 643, April 1914. ig8 SECTION G out is given by \l2\d<p = \l2(p, where (p is the angle turned through by the arm in making a complete circuit of the curve. The first instrument based onthis principle is that due to Prytz of Copenhagen. The area swept out bythe arm is made up of… … Fig. 6. approximately \l2(p if the normal to AB at A, in its initial position, dividesthe curve into two nearly equal portions. ... S-ir-cf) = ii2(pi.e. S=l2<p. Hence, if AB, AB be the initial and final positions of the arm, the requiredarea is equal to the product of / and the length of the arc…
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