A galvanometer with a mobile coil and mirror mounted on a circular bakelite platform (diameter 14 cm) with three adjustable feet and a round spirit level. The permanent horseshoe magnet is vertical and attached directly to the platform. The mobile coil is protected by two thick metal plates attached to the arms of the magnet.
Two superimposed cylinders, one slightly larger in diameter and shorter than the other, protect the mirror and the suspension wire respectively.
The overall height of the instrument is 40 cm. A window at the level of the mirror allows optical scanning of the deviations.
At the top of the case we see the screw that regulates the suspension wire of the mobile part. A 9500 ohm resistor, consisting of a small coil of thin wire, can be affiliated in series with the mobile coil when the instrument is to be used as a voltmeter. Of the three connecting terminals attached to the platform, the two on the side are directly connected to the extremities of the mobile coil while the central one is connected to one end of the mobile coil by means of the additional resistor.

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