Ruler
From Inventions
Name adopted since the fifteenth century, and perhaps already in the Middle Ages (from the Latin regula = rule).
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Inventor
Anonimo fiorentino.
Francesco di Giorgio Martini
Historic Period
1460
Description
Described by the Anonymous Florentine in codex L.IV.18 (1460, fols. 81v-82r) and by Francesco di Giorgio Martini (c.1480, fols. 30v-31r), the rule is composed of two slender rods attached at right angles and a third rod pivoting from the upper end of the vertical arm. At the foot of this arm is a hole through which passes the visual ray, guided by the sight mounted on the other end of the horizontal arm. Through this sight a distant point is observed, which is sighted also by means of the mobile rod, subsequently locked in place with a screw. The distance is measured empirically, repeating the sighting operation in an accessible place and having a mark put at the intersection of the visual rays, or by laying the rule on the ground and pulling two strings in the direction indicated by the horizontal arm and the inclined rod.
Bibliographical Resources
Anonimo fiorentino. Trattato di geometria pratica, dal codice L.IV.18 (sec. XV) della Biblioteca comunale di Siena. A cura e con introduzione di Annalisa Simi. Siena, Università degli studi, 1993, cc. 81v.-82r.
Francesco di Giorgio Martini. La pratica di geometria: dal codice Ashburnham 361 della Biblioteca Medicea Laurenziana di Firenze. A cura di Gino Arrighi. Firenze, Giunti, 1970, cc. 30v-31r.
Author of the entry: Filippo Camerota
