For measurement of small quantities of electrical charge. the moving coil is suspended by a phosphor bronze strip, which carries an optically true concave mirror. The coil can be raised, lowered or set to zero by an adjusting knurled knob at top. A knob at back is provided for clamping and releasing the coil. With levelling screws.
Sensitivity of coil 100 ohms 10-12 sec. 180 mm
Resistance Period Sensitivity of coil 500 ohms 10-12 sec. 400 mm