"Children playing in the sea, 1933."

Plastic bearing. Acetal co-polymer (black)

Copper-lead bearing. Structure of sintered

Machine for bridging a moat and scaling walls, 1588.

Title page to 'The book of various and ingenious machines', 1588.

Device for lifting a door from its hinges, 1588.

Ballista, or crosbow for projecting heavy misiles, 1588.

Machine for removing excavated earth, 1588.

Method for firing artillery at night, 1588.

Machine for lifting very great weights with ease, 1588.

Device for forcing apart the iron bars of a grating, 1588.

Device for cutting the iron bars of a portcullis, 1588.