Magnetometer

Mascart Magnetometer, one of a set given to the Specola in 1891 by Fr. Lais; made of brass in the shops of Carpentier, Paris, with a silver inlaid Vernier scale. These instruments were used for the continuous recording of variations in the Earth’s magnetic field. There are two sets of three instruments each, one set for direct measurements, the other for continuous recording on a cylinder of photosensitive paper. Each set has a single wire instrument to record the direction of the field; a double wire instrument to record the horizontal component of the field; and (shown here) a third instrument consisting of a magnetic balance to record the vertical component of the field.