ECHO-SOUNDING AND H YDROGRAPHIC AL STUDIES 



U 13 14 IS 16 17 18 19 20 21 21 23 24 2.5 If C 



39 



Temperature (T), salinity (S), and oxygen content (O2) Thermometers crushed by the 



in the Philippine Trench. is the potential temperature. pressure of the water. 



tion with light and production measurements in the upper layers, and 

 70 down to the bottom, some at great depths. 



At deep stations we would use four or five reversing water bottles to 

 the wire, with two thermometers mounted on each. But when five bottles 

 and 10 thermometers were lost owing to the breaking of a wire with 

 3,000 metres paid out, and when some other thermometers showed doubt- 

 ful accuracy, we were obliged increasingly to use only one thermometer 

 to the bottle. 



The first station was in the Bay of Biscay, where the high oxygen 

 content and salinity of the North Atlantic were immediately apparent at 

 deep levels; but here a comparison with the data of earlier observations 

 would be interesting. Off the west coast of South Africa we encountered 

 the cold but highly nutritious surface water which is sucked up from 

 some depth by the persistent easterly winds; and the deep water off the 

 southern tip of Africa clearly displayed the cold mixture of the eastward- 

 bound, south circumpolar current. 



It was with considerable excitement that we began work, on July 12, 



