National Geographic : 1932 Dec
Photographs from Dr. William Beebe THE AUTHOR MAKES ELABORATE NOTES UNDER WATER With the help of a sheet of zinc or of waterproof paper, it is easy to write details of impressions at any depth down to ten fathoms (see text, page 741). HEAVY IN AIR, THE HELMET ISLIGHT UNDER WATER The device is made of copper, with theglasses setinthefront, and rests on the shoulders. In thedepths itsweight isnegligible. Vision isclear through the windows.