Was used for the measurements for locating the south magnetic pole in 1951.
The Q.H.M. on display in real life conditions on the Dietzgen theodolite is the one used by P.N. Mayaud.
Although in 1911 the location of the magnetic pole was the subject of much speculation and had motivated several expeditions, it was 40 years before a new attempt was made, this time by the French scientist P.N. Mayaud. In November 1951, after updating measurement instruments, several raids were carried out by the French Polar Expeditions in the Antartic, with Port Martin in Terre Adélie as a base. By studying the observations made during the raids and those gleaned at Port Martin Magnetic Observatory (founded in 1951), P.N. Mayaud was able to propose a likely position for the surface magnetic pole.