Leonardo da Vincis Planungen zum Bau von Brennspiegeln

The use of burning mirrors has been an issue for Leonardo since his apprenticeship under Andrea Verrocchio (1468–70). From about 1508 he dealt more closely with the theoretical prerequisites of reflection. In his Codex Arundel and on numerous sheets of the Codex Atlanticus we find more than 200 designs belonging to the subject. Afterwards (1513–15), in the service of Giuliano de’ Medici, he planned the process-steps for the production of large concave mirrors. He set great expectations on this technology (ms. G). In this stage he complains about lack of support by two German craftsmen and encrypts his notes in cipher. Several times he remembers the problems of soldering, which his teacher Verocchio had met while soldering the spherical segments on the lantern of Florence cathedral. Numerous are the drawings of precise grinding and polishing machines for the production of mirrors. Leonardo finds a solution to avoid shading if the receptor of the solar rays obstructed the front of a mirror. Burning mirrors should heat fishponds or dyeing tubs, and they would save fire-wood during lime-burning. In the service of Giuliano, commander-in-chief of the papal army, Leonardo may well have trusted in the legend of Archimedes destructing Roman ships by burning mirrors.