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. 



