Surveying Compass

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Name currently used to distinguish the instrument used for surveying from the instrument of orientation also called compass.


Contents

Historic Period

15th-16th C.


Description

Goniometric circle similar to the horizon of Leon Battista Alberti but equipped with diopter and magnetic needle. The circumference is divided into 8 sectors designating the directions of the winds (Tramontana, Greco, Levante, Scirocco, Ostro, Libeccio, Ponente, Maestro), and each part is divided generally into 45°, for a total of 360°. In Raphael’s famous letter to Pope Leo X (c.1515), containing a first description of this instrument, the suggested division is 4 degrees for each wind, for a total of 32 degrees. The position angle of a place is read in relation to the direction of the wind blowing from the sector of the circumference carrying the diopter. The instrument is named for the compass usually found at the centre of the graduated disc.


Bibliographical Resources

Bartoli, Cosimo. Del modo di misurare le distantie, le superficie, i corpi, le piante, le provincie, le prospettive, & tutte le altre cose terrene, che possono occorrere a gli huomini..., Venezia, Francesco Franceschi, 1564.

Sanzio, Raffaello. Memoria a Leone X, in Raffaello Sanzio, Tutti gli scritti, a cura di Ettore Camesasca, Milano, Rizzoli, 1956, pp. 51-64.


Existing Instruments

Florence, Museo Galileo. Institute and Museum of the History of Science, inv. 154.
Florence, Museo Galileo. Institute and Museum of the History of Science, inv. 1279.
Florence, Museo Galileo. Institute and Museum of the History of Science, inv. 144.
Florence, Museo Galileo. Institute and Museum of the History of Science, inv. 3371.
Florence, Museo Galileo. Institute and Museum of the History of Science, inv. 2506.


Images


Author of the entry: Filippo Camerota

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