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Inventory no. 71015 - Former Display Label

English MECHANICAL EQUINOCTIAL DIAL
c.1700

Brass and silvered brass. Signed, "WM. DEANE Fecit"; undated.

This dial is similar, in design and use, to the large equinoctial ring dial by T. Heath (no. 100, shown in case no. 31), except that the equatorial ring is replaced by a clock-face a minute- and an hour-hand, controlled by the position of a moveable ring bearing the declination-scale and sights.

In use, after the usual adjustments have been made, the short index arm on one side of this ring is moved to the date. This operation causes the sights, which are on the other side, to move to the correct point on the declination scale. The ring is then turned until the sun shines through the lens in the front sight on to the spot engraved on the back "sight". The clock face then indicates the time.

On the base is engraved a scale giving the equation of time.

[108]
Lewis Evans Collection.

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