From Falkland Islands to Cape of Good Hope. 85 



Station 323 and Station 140 traverses the whole of the South 

 Atlantic Ocean from the mouth of the Rio de la Plata to the 

 Cape of Good Hope, between the parallels of lat. 35° and 38° 

 S., and only a few degrees north of what may be considered as 

 the limit between the S3uth Atlantic and the Southern Ocean. 

 It is a combination of two sections surveyed at two different 

 periods of the circumnavigation cruise of H.M.S. " Challenger," 

 and Station 333 of the homeward voyage in March, 1876, 

 nearly coincides with Station 133 of the outward voyage in 

 October of 1873. The former date being in those southern 

 latitudes the end of summer, when warm currents may be 

 expected to have attained their maximum volume and velocity, 

 while the latter date marks the beginning of spring, when cold 

 currents have acquired their greatest power, this difference in 

 the seasons ought not be entirely lost sight of in a comparison of 

 the distribution of temperature in the two portions of the section 

 east and west of Tristan d'Acunha. At Stations 317, 318, 319, 

 and 3^0, we find the Antarctic Current pressing up against the 

 coast of Patagonia and nearly coming to the surface at Station 

 317; while at Stations 318, 319, and 320, it is disguised by a 

 warm surface-stratum about 100 fathoms thick — an extension or 

 overflowing of the South Atlantic Equatorial Current between 

 Rio de la Plata and the Falkland Islands. An examination of 

 Curve Fig. 7, belonging to Station 318, shows that the Antarctic 

 current here forms a stratum of the enormous thickness of 

 about 1400 fathoms, or one and a-half English miles, with a 

 nearly uniform temperature of from 1° to 2° C. The abnormal 

 bottom-temperatures ascertained by the " Challenger " (varying 

 from —o.'^ to — o°.6 C), between Station 319 and Station 330 

 (long. 55° W., and long, t^'^ W.), a distance of over 1000 nautical 

 miles, have been alluded to in a former chapter, as well as the 

 slight increase of these temperatures towards the equator, where 

 they are still found to vary between o°.4 C. and o°.9 C. — an 



