SHEILA TERRY / SCIENCE PHOTO LIBRARY SHEILA TERRY / SCIENCE PHOTO LIBRARY
Da Vinci's underwater breathing apparatus. Drawing by Leonardo da Vinci (1452-1519) of his design for a snorkel-like breathing tube. At the top of the device is a float, whose domed shape prevents water from entering the breathing tubes. The tubes contain an inlet and outlet valve, and the sac below the chin of the user (bottom centre) is designed to collect waste. At left, a detail of the tubes is shown: they are formed of hollow canes linked by a double helix of coiled, flexible tubing to allow more freedom of movement. Due to the increasing pressure at depth, it is impossible for a snorkeller to inhale air at atmospheric pressure at even a metre down, as the lung muscles are not strong enough to work against the pressure.
Model release not required. Property release not required.