|This instrument was invented by Latino Orsini and described in his Trattato del Radio Latino, published in Rome with a commentary by Egnatio Danti in 1583 and 1586. |
The instrument is made up of a central rod on which four hinged rods move, in the form of a parallelogram and provided with sights. On the rods various scales of measurements are inscribed, such as the degree scale, the shadow quadrant, the division into braccie (Italian units of length), the wind rose, the angles of regular polygons inscribed in a circle and the diameters of shot used by artillery. A compass is housed in the handle. Once the instrument is closed, it is placed in a sheath which makes it appear like a dagger. It can be used to measure distances, heights, and depths, the elevation of cannon, the level of planes, and to carry out topographical surveys.