When used with the auxiliary field, the sensitivity can be miscellaneousd, within certain limits, also by varying the auxiliary tension.
The instrument can be mounted on a special tripod and in that case the reading of the deviations is performed (with the Poggendorff method) thanks to a small mirror attached to the wire from which the reed is suspended; it can also be mounted on a projection device, containing a projector and scale, and in that case the reading is made directly on the scale with the aid of a lens mounted on the window of the electrometer.
With a sensitivity of 1 mV/mm and the scale at a distance of 1 metre, the electrometer is quick to respond and quite stable.
When the instrument is mounted on the tripod (heavy alloy, painted black and with adjustable feet) its overall height is 20 cm. The projection device, composed of a projector and a scale with zero at the centre (graduated to 250 mm) is contained in a trapezoidal sheet steel case with three adjustable feet and is painted black.
The case, made of chrome-plated brass, is composed of two identical, vertical and coaxial cylinders (height 5 cm, diameter 2.7 cm) and of a third, horizontal cylinder (height 4.5 cm, diameter 4.6 cm) placed between the two vertical cylinders....continues