Page:Popular Science Monthly Volume 88.djvu/740

 712

��Popular Science Monthly

���working and no more. As in the case of the regulation diving-suit, the amount of air is regulated by signals, but should any accident happen at the source of air, the diver simply lifts the helmet off his shoulders and quickly floats to the surface, an utter impossibility in the regulation suit.

A small glass window en- ables the diver to see the dam- aged part, in shallow water. With this simple appliance, a rope tangled in the propeller, a broken blade, a jammed rud- der or hull punctures can be readily taken care of.

The accompanying illustra- tions were made by photo- graphing the diver in twenty feet of water at Sea Gardens along the Florida Keys.

Submarine Signaling with Sound Waves

��A^

��A submarine signaling apparatus that makes under water by vaporizing the water and thus waves which transmit the sound

front and two in back, are fastened in place by metal strips. These weights overcome the buoyancy* of the air in the hood and the natural buoyancy of the person wearing it. The buoyancy of the air in the hood tends to hold it in an up- right position. Since the weights are suspended below the center of buoyancy of the body (which is in the chest), the shoulders are held firmly in the curved lower edge of the helmet.

Fresh air is supplied to the diver by means of a single tube which leads to a small hand-pump in the boat. The pressure of the pumped air not only prevents the water from entering the hood, but keeps a fresh supply passing through at all times. Since there is no suit to inflate, pressure of the air in the helmet is always sufficient to equalize the water pressure at the depth the diver is

��sounds causing

��N improvement has been made upon the usual bell and striker for use in subma- rine signaling. By means of a new device, recently patent- ed by Theodore -Bodde, waves may be transmitted much greater distances than hereto- fore. Also, the frequency or pitch of the sound waves is entirely under control. Another advantage lies in the relatively small size of the apparatus.

An electrode i, centrally placed in the bushing 2, passes through the hull of the boat, the collar 3 holding the bushing in position. The electrode terminates ex- ternally in a sparking-knob 4. The bushing and the electrode are connected with the two brushes of an alternating current generator. A switch is inserted between one brush and the bushing for interrupting the circuit.

When the circuit is closed, the alter- nating current which is made to flow from the knob 4 to the collar 3, vaporizes some of the surrounding water. A power- ful strain is exerted on the water, result- ing in strong impulses being sent out. Signaling may be accomplished by opening and closing the switch.

�� �