Description

Extremely rare military surveyor’s rule made of brass with two movable arms pivoting around a flat hinge supporting a compass. The ends of the arms are decorated with stops and the underside of the compass is adorned with a superb rosette. Both sides of the instrument are engraved with scales and the instrument is signed “Iacobus Lusuerg Faciebat Romae A.° 1677.”.

One of the very rare artillery instruments made by the Lusuerg family and, to our knowledge, the second attributed to Jacobus Lusuerg, also the earliest recorded. It is distinguished by exceptional workmanship, with very fine engraving and a perfectly fitted hinge. It likely formed part of an artilleryman’s or military engineer’s kit, comparable to examples in the Science Museum, London, and the Museo Galileo, Florence.

Note: The instrument was used for military surveying and ballistics to set the elevation of cannons. The inscription “Pro Eleuatione Bombardæ” refers to adjusting the firing angle in order to calculate the range, using auxiliary instruments such as a quadrant, a sector for calculations, and a calliper (curved-leg compass) to measure the projectile.

References:

1) At the Science Museum, London, in a case of brass mathematical and drawing instruments signed “Dominicus Lusuerg F. Romae 1701” (inv. 1976-637). This box contains an artillery compass similar to ours but later (1701) and signed by Dominicus Lusuerg.

2) At the Museo Galileo, Florence, in a box of brass and steel mathematical instruments (inv. 243, 244, 247), from the Medici collections, most of the instruments are signed “Dominicus Lusuerg F. Romae 1710”, as well as two instruments signed by his grandfather, Jacobus Lusuerg. This box contains an instrument that is a variant of our instrument. It is equipped with sights and a ball joint for topographical use and is signed “Dominicus Lusuerg F. Romæ. 1710”.

3) At the Museo Galileo, Florence, in a box of brass and steel mathematical instruments (inv. 639, 640, 673, 703), from the Medici collections, most of the instruments are signed “Dominicus Lusuerg F. Romae 1710”, but two are older, as they are signed by Jacobus. Among the latter is an artillery rule identical to ours, signed “Iacobus Lusuerg Fā Romæ” but undated.

Dimensions: length of 22,5 cm × width of 5,1 cm × height of 1,4 cm (closed).

Italy, Rome, dated 1677.