The aerophore, an apparatus to enable a person to enter a noxious, inflammable atmosphere, was successfully tested at Chatham, 12-14 Jan 1875. Invented by Louis Denayrouze, a naval lieutenant, it comprised an air-pump, lamp, and flexible tubing*. Air in cylinders at a pressure of 300-350 lb/in2, reduced through a valve to atmospheric pressure, supported respiration. The apparatus was heavy and unmanageable for more than an hour's supply. He and Benoit Rouquayrol, a French mining engineer, had patented an underwater aerophore (1865), a steel tank filled with compressed air carried on a diver's back, connected through valves to a mouthpiece. It was the predecessor of contemporary scuba equipment.

The first U.S. patent for a submarine cable plow was issued. It was designed to feed a cable at the same time that it would dig a trench in the ocean bed. The device could be used at depths up to a half mile. The first transatlantic cable of high-speed formally was buried on 14 Jun 1938. The inventors were Chester S. Lawton of Ridgewood, N.J., and Capt. Melville H. Bloomer of Halifax, Nova Scotia, Canada. They assigned the patent to the Western Union Telegraph Co. (No. 2,607,717).