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Inventory no. 37525 - Epact entry

Epact number: 54973

Radio Latino

Signed by Giovanni Maria Mancini
circa 1600; Italian
Gilt brass; 460 mm in length (folded)

Main text

The radio latino was an instrument intended to be useful to both the gunner in elevating his cannon, and the military engineer in taking measurements and laying out fortifications. A contemporary textbook explained its application any number of practical problems of warfare. It was even designed to be reminiscent of a weapon, with its shaped handle and central arm arranged in the manner of a short sword. When folded up it was supposed to be carried in a scabbard on the military surveyor's belt.

The back of the compass box incorporated into the handle has an engraving of Christ at Calvary. It is unusual, and interesting in an instrument intended for military use, that the only figures shown at the foot of the cross are the soldiers.

Source museum: Museum of the History of Science, Oxford
Museum number: Inventory no. 37,525

Detailed text

The handle, richly decorated with strapwork and foliage, incorporates a silvered magnetic compass, the cardinal points marked with the initials of the winds, with a glass cover (needle missing). The sides of the handle have foliate decoration in relief. The back has an engraving of Christ on the cross and the signature: 'IO · MAR MANCiNVS · F ·'

There is a central arm and four arms linked by pivoted joints, one of which is carried by a decorated cursor that slides along the main arm. The central arm has an unnumbered linear scale on top. The upper surfaces of the shorter pair of pivoted arms have the same scale as the upper surface of the central arm.

Underneath the central arm has a non-linear scale 5 to 90 increasing and 90 to 20 decreasing, divided to 10, subdivided to 5 and to 1, numbered by 5, indicating the angles between pivoted arms corresponding to the positions of the cursor. The underside of one of the longer pivoted arms has shadow-square scales 0 to 12 to 0, divided to 1, subdivided to |1/4|, numbered by 3, marked 'VMBRA VERSA VMB MED VMBRA RECTA'. The other has a degree scale 0 to 45 to 0, divided to 10, subdivided to 5 and to 1, numbered by 5, marked 'AD SOLIS ET STELLARVM ELEVATIONES'.

One side of the central arm has a scale marked 'PALMO ROMANO', unnumbered but with the first inch subdivided. The other side has scales '{?B}occh de Pezzi', 1 to 120, and 'Mezo Piede Venetiano', unnumbered.

J. Bennett and S. Johnston, The Geometry of War 1500-1750 (Oxford, 1996)

Jim Bennett

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