The first engineer to combine a gas and an electric power plant in a submarine as described above was Depuy de Lôme. This French engineer turned out a wonderfully successful submarine; and this was still further perfected by another Frenchman, named Gustave Zédé. Many of the submarines used in the French Navy at the present time are of the Depuy de Lôme-Zédé type.
The Two Types of Submarines.—Two American inventors, name Lake and Holland, were working independently of each other—that is, neither knew the other was working on submarines—and each developed a different type of undersea boat. This was about 1896.
FIG. 8. THE LAKE SUBMERSIBLE BOAT.
The Lake Submersible.—The first underwater boat built by Simon Lake was shaped very much like a ship. The hull was mounted on wheels, so that it could travel on the bottom of the sea if need be, for it was originally intended to be used by pearl divers and oystermen.
FIG. 9. THE HOLLAND SUBMARINE BOAT.
In the early part of this chapter I told you that the word submarine means anything that lives in, is done, or works beneath the water-line of the sea. Now, in naval engineering, submarine has come to mean an undersea craft that can dive, while an undersea boat that simply sinks on an even keel is called a submersible. So the Lake shown in [Fig. 8] is a submersible, for it is not intended to dive.
