A vertical galvanometer with a fixed coil having a coarse and fine winding and a controlling magnet. It can be turned on a tripod.

Functioning:
Galvanometers are sensitive instruments usually used for measuring small currents. The can be used as amperemeters or voltmeters. The instrument is balanced by turning the magnet over the coil.

The French Physicist M. Boyrbouze conceived this galvanometer in roder to send signals for Paris during the siege bu Germans in 1870.
(See: http://earlyradiohistory.us/1901fa11.htm)