Claw of Archimedes Claw of Archimedes The Claw (, "harpágē", "snatcher") of Archimedes (also known as the "iron hand") was an ancient weapon devised by Archimedes to defend the seaward portion of Syracuse's city wall against amphibious assault. Although its exact nature is unclear, the accounts of ancient historians seem to describe it as a sort of crane equipped with a grappling hook that was able to lift an attacking ship partly out of the water, then either cause the ship to capsize or suddenly drop it. These machines featured prominently during the Second Punic War in 214 BC, when the Roman Republic
SS Archimedes 1836 patent. Following the ship's entry into service, the propeller would subsequently undergo a number of modifications, the most important of which were an alteration to a double threaded/half turn format, and a division of the original 360° screw into two separate blades. The propeller had the unusual feature of being fully retractable in order to reduce drag when the ship was under sail—a task that took about 15 minutes. "Archimedes" made her maiden voyage, from London to Sheerness near the mouth of the Thames, commencing 2 May 1839. On the 15th, she commenced her first sea voyage, from Gravesend