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, allowing the creature to also move forward.
While humans have attained some remarkable achievements in jet propulsion, we should pause to reflect that the Creator of the heavens and the earth, and of all living things, was the one who invented it first.