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.