The Museo Galileo has recently acquired a dagger-shaped compass by Benvenuto della Volpaia, one of the most famous Florentine clockmakers of the sixteenth century. The initials of the maker, B∙V, are engraved on one leg of the instrument, as in the analogous compass of the same author already present in our collections with the inventory number 2515.
The two compasses - together with a third in a private collection, also signed B∙V - were ordered by Pope Clement VII (Giulio Zanobi di Giuliano de' Medici) immediately after the siege of Florence in 1530. On the occasion of that historic event that would put an end to the Republic and restore the power to the Medici, Benvenuto della Volpaia was charged with an espionage action: secretly carrying out a survey of the city and the Oltrarno hills in order to build a model in wood to allow the Pope to follow the siege developments from Rome. The model was built by the sculptor Niccolò Pericoli, called Tribolo, and sent to Rome with as much secrecy, hidden "in some bales of wool that went to Perugia" (Benedetto Varchi, Storie fiorentine).
In its dual mathematical and military function, the compass disguised as a dagger was almost certainly ordered to simbolically celebrate that historic undertaking.