SHEILA TERRY / SCIENCE PHOTO LIBRARY SHEILA TERRY / SCIENCE PHOTO LIBRARY
Leonardo da Vinci produced several designs for ornithopters but this drawing can be interpreted as acceptance that man-powered flight is not practicable and that some form of mechanical power is required. Within the small sketch on the left is written 'fondamento del moto' (foundation of motion) and the spring-loaded device depicted is similar to those in his 'automobile' and clock mechanisms.
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