SECT. 1] 



gINGLE-SHIP SEISMIC REFRACTION SHOOTING 



B. The Sono- Radio Buoys 



43 



There are two types of buoy at present in use. The hrst contains the radio 

 transmitter and its associated dry batteries. The second, which is considerably 

 larger, contains a transmitter, a radio receiver, the dry battery supply and an 

 eight-channel 35-mm photographic recorder, associated filters, and amplifiers. 

 A photograph of one of the smaller buoys is shown in Fig. 4. 



Fig. 4. A photograph of a sono-radio buoy and hydrophone. The 8-ft-long bottom pole, 

 made from galvanized iron tubing, is not shown. 



The bottom poles are 8 ft in length wdth lead weights at their bases to main- 

 tain the buoy-can vertical. The top poles are 11-ft bamboos with heavy gauge 

 copper wires strapped to them; these wires act as aerials. The poles are mounted 

 on the aerial insulators on the tops of the buoys. A small flag is tied to the top 

 of the pole. 



