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 302
ment by theWatkins factorial method. The two circular scales are divided logarithmicallyinto sixty parts. The pointer being set to the multiplying factor (9 in theillustration), the required time of development (usually in minutes) is read INSTRUMENTS OF CALCULATION 273 on the outer scale against… … Fig. 3. The Time Thermometer (fig. 4) utilises a logarithmic scale in aninteresting way. It has been found that the correct times of developmentare indicated against an even division temperature scale by a logarithmictime scale, as shown in rig. 5. Two things require to be settled to make…
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