Movable quadrant by S. Menini - Bologna, 1710: brass and iron, radius 100 cm.

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Movable quadrant by S. Menini - Bologna, 1710: brass and iron, radius 100 cm.

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This instrument was used in Bologna by Eustachio Zanotti in order to take the positions of Venus on the Sun during the 1761 transit. It is fitted with two telescopes, one fixed the other movable. It had been made in 1710 by the Bolognese watch-maker Sante Menini, as witness the inscription in the central brass escutcheon - "Sante Menini orologiere/ in Bologna 1710" - under the motto "Suum volvens/ audax industria/ mundum".

We know that the instrument was very successful and that other quadrants were ordered from Menini. At a certain point, however, he turned down the many requests he received on account of the harm caused him engraving scales of this size which he did using nitric acid. The decision was perhaps somewhat belated, since shortly after the craftsman was to die.

One of the telescopes is missing together with the object lenses of the second which apparently was the movable one. The connection to the limb has been restored in 1979. Of all the quadrants at the Specola this is the only one that still has its joint which allowed it to be used as an astronomical sextant.

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Object contributed by Museo della Specola, Department of Astronomy, Universit? di Bologna

Object 9 of 14 objects associated with "1761".

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