"Squadra mobile" (folding square)

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Name coined by the inventor.



Ottavio Fabbri

Historic Period



Instrument for architectural drawing and measurement. It is a sophisticated version of the square perfected and described by Ottavio Fabri for performing any kind of measurement, from levelling land and canals to calculating heights, distances and depths, and to urban and territorial surveying with the relevant cartographic drawing. The two arms (one called stationary, the other mobile) are fitted with sights. The mobile arm rotates 180° along a half-circle with the degree scale (attached to the stationary arm), whose first quarter bears the shadow square, also called altimeter scale. The instrument thus served as quadrant, geometrical square and compass.

Bibliographical Resources

Fabri, Ottavio, L'uso della squadra mobile con la quale per teorica et per pratica si misura geometricamente ogni distanza altezza, e profondità, s'impara a perticare, livellare, et piglare in disegno, le città, paesi, et provincie, il tutto con le sue dimostrationi intagliate in rame, appresso Francesco Barilleti, Venezia, 1598.
Scamozzi, Vincenzo, L’idea della architettura universale, Venezia 1615, Parte I, Lib. I, Cap. XV, p. 51: “la lettera X figura la Squadra mobile con la quale si forma ogni sorte d’angoli”.

Existing Instruments

Venezia, Museo Correr, Cl. XXIX, 21.


Author of the entry: Filippo Camerota

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