Gnomonic Stylus
From Inventions
Has no specific name.
Contents |
Inventor
Giovanni Battista Vimercati
Historic Period
1565
Description
Simple but ingenious procedure described by the Carthusian monk Giovanni Battista Vimercati for enlarging the drawing of a sundial to the desired scale. The drawing is spread out on a table big enough to hold the enlarged drawing as well. In place of the gnomon, a stylus proportioned to the size of the desired dial is used. If the drawing is to be four times larger, the gnomonist must place another stylus four times longer than the first on the table. The drawing is reproduced by moving the table in the sunlight so that, at each move, the shadow of the shorter stylus touches a significant point on the dial. The corresponding position of the longer stylus’s shadow is then transcribed onto the sheet of paper. In his treatise on perspective Daniele Barbaro describes this procedure used also to reproduce "a fortress, a human figure, and anything else".
Bibliographical Resources
Vimercati, Giovanni Battista, Dialogo della descrittione teorica et pratica degli horologi solari, Venezia 1565, parte II, capp. II, IV, V.
Barbaro, Daniele, La pratica della perspettiva, Venezia 1569, Parte IX, cap. V.
Author of the entry: Filippo Camerota
