Deductions from the Curve. 43 



temperature of 4 . 1 C. at 300 fathoms, of 3 C. at 900 fathoms, 

 and of 2 C. at 1 500 fathoms. The temperature of the surface 

 has fallen from 24 C. to n°. 1 C. The space which contains 

 the three stations covers i° 2c/ of latitude, and i° 57' of 

 longitude — truly an extraordinary change in the distribution 

 of temperature in so small a portion of the Atlantic. 



In Fig. 3, the Curves A, B, C illustrate the gradual dis- 

 appearance towards the Azores of the same stratum, 300 fathoms 

 in thickness, which appears in Curve A, Fig. 2. 



In Curve A, Fig. 4, the hump between 200 and 700 

 fathoms (12 C. to 7°.5 C.) marks the presence of a large 

 current flowing between the Azores and Madeira ; and the low 

 gradients of Curve B indicate the existence, between the surface 

 and 1500 fathoms, of various strata of gradually decreasing 

 temperatures moving more or less in the same direction. 



Curve A, Fig. 5, shows the rise of temperature caused by 

 the Agulhas current, to the southward of the Cape of Good 

 Hope; while Curve B of Station 139, situated but a short 

 distance westward of the Cape, affords little or no indication of 

 the proximity of this large current of warm water. The 

 unusually irregular shape of Curve B betrays the existence in 

 the vicinity of the Cape of numerous currents moving in different 

 directions one above the other. 



The two curves in Fig. 6 illustrate the temperature-con- 

 ditions in the great South Australian current. H.M.S. "Chal- 

 lenger," after a three months' cruise, her stores of coal having 

 run short, was precluded from establishing numerous stations 

 on her way from the Antarctic Circle to Australia. Thus it 

 was found, on arriving at Station 159, that the ship had already 

 crossed the southern limit of this great current, of which, at 

 Station 158, in lat. 50 S., long. 123 E., there had been little 

 or no trace (Plate 12). The isotherm of 5 C, which at the 

 latter station was reached at a depth of 200 fathoms, fell to 600 



