OCEANOGRAPHIC INFORMATION FOR SUBMARINE CABLES 



10G9 



(c) Sound investigations. 



(d) Investigations of magnetic and gravity fields, and heat flow. 

 Visual inspections have been performed by divers in depths up to 



only about two hundred feet. Vessels such as the bathyscaphe must be 

 employed for greater depths but their design precludes any extensive 

 observation of the sea floor. 



Bottom photographs in shallow waters are fairly numerous but those 

 taken in depths greater than 1,000 fathoms are still rare. Good photo- 

 graphs usually show an area approximately 5 ft by 8 ft and are focussed 

 well enough to make objects and organisms | inch in diameter clearly 

 identifiable. A compass and a current indicator are often lowered with 

 the camera and included in the photograph. These provide indications 

 of current velocity and direction and a means of orienting the bottom 

 features. Locations of almost all deep water photograph stations in the 

 Atlantic are shown on Fig. 10, and a typical deep sea camera rig is de- 

 picted in Fig. 11. 



I 



/ ,- 



CAMERA — 



/ / 



/ I 



/ 

 / 

 / 

 / 

 / 

 / 



V 



-15"h 



> 



I 



7' 



I 



I _LIGHT 

 ■ I SOURCE 



-I 



I 

 I 



I 



-f-SWITCH 

 3' 



3*--^ — SPRING 



iV ARFA OF -^t^ /iLra'' ^.j ^^ ( 



AREA OF 

 PHOTOGRAPH 



— >T<- 



-4-3"-- 



-^ CONTACT 

 PLATE 



Fig. 11 — Diagram of miilti])lo-shot uiidorwalor camera taking a bottom picttire. 



