LEONARDO da Vinci
(b. 1452, Vinci, d. 1519, Cloux, near Amboise)
Biblioteca Ambrosiana, Milan
From the Codex Atlanticus.
Rotating poles sweep atackers off the walls. One wonders how effective this would have been. The mechanical workings are essentially the same as that used in a mill of the same period; Leonardo was simply looking for a new application of the device.