59 



most of the time was spent, prevented a more numerous result. The 

 weak signals seemed to be caused by trouble in the sound-receiving 

 and amplifying devices. The oscillators in the hull sent out good 

 signals, but it was very difficult to pick up the echoes in the head 

 telephones. 



The apparatus worked well during the fifth cruise. Soundings up 

 to 2, GOO fathoms were obtained. Besides tabulating for reference 

 251 depths taken when the ship's position was well fixed, the instru- 

 ment was an invaluable aid in locating the ship during thick and over- 

 cast weather. 



The sixth patrol cruise produced 97 values for the depth records; 

 330 soundings were obtained but the majority were thrown out on 

 account of doubtful positions due to the impossibility of getting 

 enough sights. The short seventh cruise furnished 31 good sound- 

 ings to be added to the season's total. 



It was noted that when the depth finders were in good v.oiking 

 order, results in water up to 1,000 fathoms in depth could usually be 

 counted on. The deepest soundings were all made under especially 

 quiet wave and sea conditions. Very likely on ships using less 

 electricity than the electric-drive ice-patrol vessels better results 

 would be obtained. The Diesel-drive cutter Marion, on the Marion 

 Expedition, shortly after the termination of ice patrol could sound 

 with her instruments of the same make down to 2,000 fathoms 

 consistentl,y, so long as the radio apparatus was not being used. 

 Whenever the near-by transmitter was sending the fathometer was 

 strongly affected with induced noises that entirely blotted out the 

 incoming echoes. Such a condition did not exist on the ice-patrol 

 cutters where the radio room was a long distance aft of the bridge, 

 but no doubt some of the noises that interfered with the hearing of 

 weak echoes were picked up from the numerous strong electric fields 

 on board. 



