244 



DEPTHS OF THE OCEAN 



an increase of density, but the differences are not so great as 

 to forbid the inclusion of the three stations in one region with 

 regard to the upper water-layers ; it is a region with a southern 

 character. 



The conditions are widely different when we come to a 

 northerly region, like that where the East Greenland Polar 

 Current and the Labrador Current bring down great water- 

 masses from the Arctic seas. On our passage to and from 

 St. John's we sailed across the Labrador Current and took a 

 number of observations at different places in it. Fig. 170 shows 

 the conditions at Station 76, due east of St. John's, towards the 

 eastern margin of the cold current. Here the temperature at 

 the surface was about 6° C, falling rapidly to —0.35° C. at 55 

 metres (30 fathoms), rising again, at first rapidly, to 3^ C. at a 



M. 



/oo 



Ji6o 

 33 



■ees 



33 6 

 Z" . 3° 



g7o 



3i.o 



4' .5" 



J'fS 



i'ao 





Fig. 170. — Temperature, Salinity, and Density at Station 76, in the eastern part 

 OF THE Labrador Current, off Newfoundland (9th July 1910). Depth in metres. 



little more than 200 metres, and then slowly to 3.4" C. towards 

 the bottom in about 400 metres. If the depth had been 

 greater, we should have found that the temperature fell 

 again as we penetrated into the deep water. This is an 

 example of the usual conditions in Arctic and Antarctic regions, 

 where in summer the temperature decreases gradually from the 

 surface to a minimum at 50 to 70 metres, then rises to a 

 secondary maximum at 300 to 400 metres, falling again towards 

 the bottom, and it is in a case like this that the ordinary 

 maximum and minimum thermometer is inadequate (see p. 216). 

 At Station 76 the water was warmer through the influence of 

 the Gulf Stream ; it was much colder, for instance, at Station 75 

 farther west, where we found -1.43° C. at 55 metres, and at 

 Station 74, just off St. John's, where the temperature was —1.52° 

 at 91 metres. As a rule, it may be said that in a polar current 



