As far as we know, the Rothé-Carpentier balance on display here is a unique prototype. It was designed around 1930 in Strasbourg's Institute of Globe Physics to be used on field in the study of regional magnetic anomalies. It was used in 1935 in Welschbruch magnetic station 40km south of Strasbourg. This recording balance was used as a reference apparatus in the study of magnetic anomalies in the Vosges dyorite mountains at Neuntelstein. In spite of several technical advantages, which were publicised, this balance had no real commercial success. The EOST still uses Welschbruch experimental station for developing magnetometry equipment for use in the French Austral and Antarctic magnetic observatories.
The sensitive parts of the Rothé-Carpentier balance are enclosed in a sealed metal box. The removable cover contains the optical recording system (the photographic recorder itself is not displayed here). The mobile equipment is made of two magnetic steel or cobalt blades and the counterweights can be fixed from the outside, which is in fact the originality of the apparatus compared with foreign models made at the same time (Schmidt's balance, for example). The box rotates on a platform which carries a graduated disc, and a compass shows the direction of the magnetic meridian. As in the case of the other balances, sensibility is controlled by using two Helmholtz coils.