Leonardo's design for an underwater breathing apparatus consists
of cane tubes joined by leather, with steel rings to prevent them
being crushed by the water pressure. The tubes are attached to a
face-mask and at the other end to a bell-shaped float to keep the
openings above water.
A diving suit based on this design using pig leather, bamboo tubes,
and a cork float was built, and tested by a diver, Jacquie Cozens.
It worked well in shallow waters.
Other drawings for diving suits included a coat with a pouch to
hold a leather wineskin to store air and a urination bottle so the
diver could remain underwater for a long period.
Leonardo's vision of storing air in a wineskin was revisited in
1825 when an aqualung for compressed air was outlined by the English
engineer, William James. The necessary valve was designed by Emile
Gagnon and Jacques Cousteau in 1943.