Tank

The idea of a covered vehicle that could penetrate enemy lines, followed by soldiers, had already appeared in the Middle Ages and was enthusiastically taken up again in the 15th century.

Leonardo designed a heavy vehicle shaped like a tortoise with cannons all round it and perhaps reinforced with metal plates. Some people had thought of moving it with sails, but Leonardo's solution was a system of gears moved by cranks which were worked by eight men inside.

He even thought of using horses instead of men but the risk of the animals manicking in such a tight, noisy space made him change his mind.

Credit : HK Sciences Museum.