Joseph L. Boucher and Emery H. Brault and Romuald Filteau took out a patent for an improved diving-dress in 1891. They do not seem to have hampered by any previous acquaintances with practical diving operations, for they calmly state;

“… With the ordinary diving suit the pressure of the water on the body and limbs increases in such ratio as the diver descends that it is not practical to work at a greater depth than about forty feet…”

After this, it is scarcely surprising to find that the invention itself is typical of the amateur dabbler. It consists of three pieces of armour, interlocking in the manner of a jig-saw puzzle, and covering the diver’s head and trunk. Over this an ordinary diving-dress is to be worn. As in the case of Don Quixote’s helmet, cardboard armour would look just as well and be equally useful.

R.H. Davis "Deep Diving and Submarine Operations" page 590