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 237
>*r Fig. of two readings from an area, one with the pole to the left of the tracer arm,the other with the pole to the right, as indicated in rig. 4. With the Amslerplanimeter this cannot be done. The tracer arm is mounted above the polearm, and so the range of the tracing point is restricted.… … Fig. 5. INSTRUMENTS OF CALCULATION 209 made, and so any error due to improper mounting of the recording wheelcan be eliminated. Another type of Amsler planimeter is illustrated in fig. 6. The advantageof this type lies in the fact that the recording wheel works on a revolving disc
