Declination compass

25 x 25
Engraved metal, wood and brass

INDEX 1788 : M.IV.53

Pyxis magnetica, cujus Acus longa est poll. 8 elegantissime fabrefacta.

Magnetic box with an eight inch long needle, very artistically fashioned.

This handsome compass, mounted on a square of brass, made in England by George Adams, belongs to the group of instruments used to study magnetism. It is kept in a wooden box.

The needle is attached to a spike and turns on a vertical axis. Beneath the needle is a fine engraving of the compass, rose, bordered by a graduated circle.

The compass rose and magnetic needle are contained in a round box, about 2.5 cm in height, with a 22 cm diameter glass top, the same size as the compass rose. Thirty-two points are indicated and the four cardinal points are highlighted. As with the previous instrument, North is indicated with a fleur-de-lis.

The circle bordering the compass rose is graduated in ten degree intervals; the outer perimeter of this scale has a second circle, graduated from 0 to 360o at half degree intervals. The compass bears the following inscription: "Hoc Instrumentum factum fuit a GEO. ADAMS in Fleet Street LONDINI".

From Colégio dos Nobres, catalogue n.º 49.

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