Museo Galileo
Virtual Museum
Surveying compass
    • Setting:
      Room VI
    • Maker:
      Matteo Botti, Giovanbattista Botti
    • Place:
    • Date:
      17th cent.
    • Materials:
    • Dimensions:
      diameter 180 mm
    • Inventory:
    • Surveying compass (Inv. 2506)
    • Surveying compass (Inv. 2506)

Surveying compass consisting of a disk whose circumference is divided into eight 45° sectors carrying the names of the winds. On the lower half is engraved a double shadow square. In the upper part is a horizontal sundial with a gnomon on the alidade. The alidade, equipped with viewers, rotates around a magnetic compass complete with a glass cover and a magnetic needle. The magnetic declination, of 5° W, is indicated under the compass. At one end of the alidade is fixed a perpendicular bar, tangent to the circumference. The bar could be used for architectural surveying as a means of measuring the declination of the walls of a building. There are no markings on the back of the disk except the names of Matteo and Giovanbattista Botti. We have no information on Giovanbattista. Provenance: Medici collections.