Immagini

DESCRIPTION

Exhibit 635 is an original astatic galvanometer invented by Nobili. It is based on the principle that the permanent magnetic needles, constituting the moving part are really two needles with opposite magnetic poles tied together with one inside the fixed coils and one above the coils. In this way the galvanometer is insensitive to the earth's magnetic field, while the field of the coils provides torques on the two needles in the same sense. The double astatic needle is attached to a silk thread suspended by a tension screw at the top of the glass column that protects the silk thread from external perturbations. The orientation of the upper needle as referred to a 360 graduated scale provides the value and direction of the current in the fixed coil (or coils).

The instrument is mounted on a circular wood with three leveling screws. This model has two fixed coils and thus four terminals.

ISCRIZIONI

1. Sulla base di legno c'è un'incisione leggibile in piccola parte:
   "...ATH ..DAM"

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