from the Falkland Islands to Monte Video. 629 



again a little more rapidly to — 0°*4 at the bottom. At the next Station 

 (326) all the upper temperatures were remarkably low, corresponding 

 with the cold "interdigitation" in the Brazil current. Stations 328 and 

 329 repeat Stations 324 and 325 with little variation ; at the three Sta- 

 tions 330, 331, and 332 there was a most marked hump on the curves, 

 occupying roughly the space between 150 and 250 fathoms ; and at the 

 three succeeding stations, 333, 334, and 335, the hump wore out and 

 finally disappeared. 



The high surface-temperatures between the mouth of the Eiver Plate 

 and Station 328 are doubtless due to solar radiation (early autumn tem- 

 perature) plus the additional warmth of the Brazil current, which is 

 logged from the 29th of February to the 10th of March as running in a 

 generally southerly direction at an average rate of 20 miles a day. The 

 rapid fall for the first 150 fathoms represents mainly the loss of the heat 

 due to direct radiation, which does not affect the curve to a depth much 

 greater than 100 fathoms ; and the hump from 150 to 250 fathoms re- 

 presents the extra effect of the current, which appears to have there an 

 average depth of 250 fathoms ; it seems, however, not to be very con- 

 stant, either in volume, direction, or rate. 



To recapitulate briefly the more important points with regard to the 

 distribution of temperature : — 



1. The section between Monte Video and the meridian of Tristan 

 d'Acunha includes, besides the soundings on the South-American plateau 

 and the sounding on the " cold wall," a series of soundings in a western 

 trough with an average depth of 2750 fathoms and an average bottom- 

 temperature of — o, 4 0. ; and a series of soundings on the middle bank 

 of the Atlantic, with an average depth of 1850 fathoms and a mean bot- 

 tom-temperature of 1 0, 3 C. 



2. In the trough a huge mass of Antarctic water at temperatures 

 ranging from 1°*5 C. to — o, 6 C. is creeping northwards at depths 

 greater than 1800 fathoms ; on the rise very little water at a lower tem- 

 perature than 1°*5 C. passes northward ; but that is only on account of 

 the absence of the required depth, for the isothermobaths of 1°*5 and 2° 

 C. are practically at the same level over the central plateau and over the 

 trough. 



3. On the surface a warm current, perhaps about 800 miles wide, and 

 affecting the temperature of the water to a depth of 250 fathoms, con- 

 tinuous to the northward with the southerly deflection of a part of the 

 equatorial current, passes to the southward, taking a slightly easterly 

 direction on account of its higher initial velocity. 



4. As a rule, the temperature falls rapidly throughout the section to 

 a temperature of 3° C. at 600 fathoms, and then extremely slowly to 

 the bottom. 



We had always attached special importance to the temperature- sound- 

 ings on this section, for we had expected them to throw some additional 



