An air-lock separates the diver’s section from the main hold so that it is possible to pass from one to the other while the entrance to the sea is still open.  A person entering the lock from the large room first closes the door between and then gradually admits the compressed air until the pressure is the same as in the diving compartment, when the door into it may be safely opened.  When returning, this operation is simply reversed.  The lookout stands forward of the diver’s space.  When the Argonaut rolls along the bottom, round openings protected with heavy glass permit the lookout to follow the beam of light thrown by the searchlight and see dimly any sizable obstruction.  When the diving compartment is in use the man on lookout duty uses a portable telephone to tell his shipmates in the main room what is happening out in the wet, and by the same means the reports of the diver can be communicated without opening the air-lock.

This little ship (thirty-six feet long) has done wonderful things.  She has cruised over the bottom of Chesapeake Bay, New York Bay, Hampton Roads, and the Atlantic Ocean, her driving-wheels propelling her when the bottom was hard, and her screw when the oozy condition of the submarine road made her spiked wheels useless except to steer with.  Her passengers have been able to examine the bottom under twenty feet of water (without wetting their feet), through the trap door, with the aid of an electric light let down into the clear depths.  Telephone messages have been sent from the bottom of Baltimore Harbour to the top of the New York World building, telling of the conditions there in contrast to the New York editor’s aerial perch.  Cables have been picked up and examined without dredging—­a hook lowered through the trap door being all that was necessary.  Wrecks have been examined and valuables recovered.

[Illustration:  SINGING INTO THE TELEPHONE Part of the entertainment furnished by the telephone newspaper at Buda-Pest.]

Although the Argonaut travelled over 2,000 miles under water and on the surface, propelled by her own power, her inventor was not satisfied with her.  He cut her in two, therefore, and added a section to her, making her sixty-six feet long; this allowed more comfortable quarters for her crew, space for larger engines, compressors, etc.

It was off Bridgeport, Connecticut, that the new Argonaut did her first practical wrecking.  A barge loaded with coal had sunk in a gale and could not be located with the ordinary means.  The Argonaut, however, with the aid of a device called the “wreck-detector,” also invented by Mr. Lake, speedily found it, sank near it, and also submerged a new kind of freight-boat built for the purpose by the inventor.  A diver quickly explored the hulk, opened the hatches of the freight-boat, which was cigar-shaped like the Argonaut and supplied with wheels so it could be drawn over the bottom, and placed the suction-tube in position.  Seven minutes later eight tons of coal had been transferred from the wreck to the submarine freight-boat.  The hatches were then closed and compressed air admitted, forcing out the water, and five minutes later the freight-boat was floating on the surface with eight tons of coal from a wreck which could not even be located by the ordinary means.