lens jacket
1.Among the designs left by Leonardo da Vinci almost 500 years ago—with notes written backward to be read with a mirror—were the parachute，life jacket， water pump，swim fins，Well digger，paddle-wheel boat，horseless carriage ，sprocketchain， steam gun， water turbine，lens-grinding0 machine，shrapnel ，machine gun， airplane， helicopter，submarine，and mass production .
