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 241
The motion of the recording pen is always parallel to theplane of a small, sharp-edged, non-slipping wheel w. By means of the parallelframework shown, the plane of the wheel w is maintained parallel to theradial bar. When the tracing point is being guided round the given curve,the scale bar is… … Fig. 12. Since the wheel w is at any instant moving in the direction of its planeat that instant, guiding the tracing point round a curve such as OP resultsin the machine drawing a curve such as 0^. The end ordinate H1P1 of thecurve traced out by the machine is a measure of the area ORP roun4…
