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 301
d or in the centre. (2) Pantograph. By Carey, London.Exhibited bv the Mathematical Laboratory, University of Edinburgh. XIII. Watkins Instruments for Calculating Times forPhotographic Exposure and Development. These all use logarithmic scales arranged as described below :— The Standard Exposure… … Fig. 1. on each scale, the two end scales being fixed on the bod} of the instrument,while the two central scales revolve with the movable pointers. After theseparate pointers P, D, and A are set to the required values, the final pointerE indicates the cumulative result on the final exposure scale.…
