Chap. 12] 



MISCELLANEOUS GEOPHYSICAL METHODS 



955 



trated in Fig. 12-24. Both transmitter and receiver are high-frequency 

 (16,000 cycles) magnetostriction units and are mounted on opposite sides 

 of the ship in water-filled tanks. The sound impulse is initiated by dis- 

 charging a high tension generator through a condenser into the windings 

 of a submarine oscillator, the transmission key being actuated by the 

 recorder itself when it reaches the zero position. The recording unit is 



PMOTOtLCCTRiC 



fllOvelU 

 60 eyclta 



^TUNING rORK 



i 

 >t025 eyela supply 



-»KEVING CIRCUIT 



-^ 1T.5 k.c supply — - 



llOvelU 

 0O eyclas 



CONVERTOR 



— n — 



t10v*Ks,O.C. 

 SHIPS SUPPLY 



II 



Fig. 12-23. 



U. S. Coast and Geodetic Survey 



Schematic circuit of Dorsey fathometer. 



essentially a spiral drive which moves a stylus back and forth across re- 

 cording paper impregnated with starch iodide. An imprint is produced by 

 liberating iodine when current passes through the stylus and the paper to 

 a metal roller beneath the paper. When the stylus is at the edge of the 

 paper, the transmission key is closed and current passes through the stylus, 

 thus marking the instant when the signal is dispatched. On arrival of the 

 echo, current is again passed, thus producing a continuous record of the 

 ocean bottom. With these high-frequency recorders it is possible to dif- 



