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Inventory no. 50889 - Epact entry

Epact number: 35728

Surveying Instrument

Signed by Tobias Volckmer
Dated 1612; Brunswick
Brass; 1 x 88 x 195 mm

Main text

This surveying instrument brings together a number of functions in a neat design. Horizontal angles can be measured using the compass and the pivoted alidade at one side means that bearings of elevated or depressed positions can be taken. Bearings can also be measured by the alidade on the quadrant, using the compass for orientation. The grid within the quadrant is used for calculations involving right-angled triangles, while on the reverse is a set of linear scales with the standards of different cities.

There is no sign of any means of fixing the instrument to a stand and it was probably meant for use on a plane table, at least when taking sights. The long edge, with a scale of inches, could be used in conjunction with the alidade on the quadrant. This alidade has a stud for stopping it when it is parallel to the edge, while the other one is pierced to allow a clear view of the sights in that position.

Source museum: Museum of the History of Science, Oxford
Museum number: Inventory no. 50,889

Detailed text

The surveying instrument has on one side a pair of sights, moveable in the vertical plane, on a decorated arm. On the same side is a wind rose with three concentric divisions; the first is 1 to 12, 1 to 12, the second is 1 to 24, the third is in 360° by 2°. A further inner scale is divided in transversals. The spandrels are decorated with fruits and flowers. Next to the wind rose is a pair of two calibrated rules from [0] to [25] by 5, one of which is equipped with sights. They can both move over a quadrant of degrees divided [5] to 25 by 1 to 5, and on the limb divided 0 to 90 in both directions. Within the quadrant is a sine and cosine diagram. Next to the edge of the instrument is a graduation [0] to 9 by 1.

On the other side is the signature 'TOBIAS VOLCKMER BRAVNSWEIGENSIS · SERENI: DVCIS BAVARORVM &c: Mathe: & aurifaber faciebat · anno 1612'. Below it is a comparative table entitled 'HALBER WERCKSCVECH ETLICHER STEDTE' ('half foot of a few cities'), showing the inches of the foot-measures of Strasbourg, Munich and Brunswick (indicated 'MVNCHEN & BRAVNAV'), Nuremberg ('NVRNBERG'), Salzburg ('SALTZBVRG'), Regensburg and Augsburg ('REGENSPVRG & AVGSPVRG'), Vienna ('WIEN'), Landshut ('LANDSHVT'), Paris, Venice and Innsbruck ('PARIS ET VENETIA ET INSPRVK').

Ilaria Meliconi

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