Scorpion or catapult, c 1750.
© Science Museum / Science & Society Picture Library
Model. The scorpion was a device used by the ancient Romans to throw stones. Dr Stephen Demainbray (1710-1782), a science lecturer, used this model to demonstrate a lever in action. The long arm, or tail, was pinned down and a misile was attached to it. When released, the weights on the short arms fell and the misile was hurled into the air.