Magnetometers are instruments that measure the intensity of a magnetic field and the magnetic moment of a bar magnet by means of the deviation or oscillation of a magnetic needle of a size small enough to allow us to consider the field uniform throughout the region it occupies.
Magnetometers have been used mostly in the study of the Earth's magnetic field and its miscellaneousations and, basically speaking, they use the methods proposed by Karl Friedrich Gauss (1777-1855) who is considered the inventor, some time about 1827. The specimen exhibited here, which is the single-fibre type and which is equipped with a large number of accessories, is without any instructions for its use, which certainly must have been rather complex. It is entirely made of burnished brass, with the exception of the four vertical walls of the case and the sleeve that protects the fibre from which the magnetic needle is suspended, which are made of glass, and the magnetic needle itself.
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