Fig. 1. (A) The hand-held masses (halteres) used to increase the long-jump distance in ancient Olympics. (B) Drawing by Giovanni Alfonso Borelli (1608–1679) published in his `De Motu Animalium', suggesting the use of fins in swimming. (C) The human-powered aircraft from the Nihon University Aero Student Group (NASG), flying for almost 35 km at the 27th Birdman Rally (Japan) in 2003 (www.nasg.com/birdman/bm-e.html). (D) The Decavitator, a hydrofoil-based boat with a crank-operated propeller, capable of a speed of about 34 km h^–1 on the water surface.