Who invented jet propulsion?
Jet propulsion is commonly believed to be a modern breakthrough. The modern jet engine, in fact, dates only from the 1930s. However, the possibility of jet propulsion was demonstrated long ago. A Greek mathematician and scientist, Hero of Alexandria, produced a working model of a steam-powered engine (a forerunner of the jet engine) as far back as the first century AD. But even before this, jet propulsion was in use. A class of molluscs known as cephalopods, which includes the squid, are amazingly fast-moving creatures. Squid have been recorded escaping from predators at an incredible 55 kilometres an hour (34 miles per hour). By squirting a strong jet of water from a tube, or funnel, squid propel themselves through the water at remarkable speeds. Muscles contract to force a narrow jet of water out through the funnel, and the squid rockets off — backwards! This backwards jet propulsion may seem an odd arrangement, but the squid’s funnel is flexible, and can bend around 180 degrees, all
