THE GUINEA GURBENT. 



329 



The temperature of the Guinea Current is high, and demonstrates its 

 Equatorial origin, although the branch of it which comes from the North- 

 ward past Cape Verde has probably a lower temperature as coming from 

 a higher latitude. The Equatorial Current to the Southward of the 

 Guinea Current is also of a lower temperature, coming direct along the 

 African coast from the Southern Polar regions. The mean summer tem- 

 perature is about 78°, but in our winter and autumn months it is higher, 

 being from 82-6" to 83° as a mean, and sometimes it is found higher than 

 this. 



(281.) H.M.S. Challenger, in crossing this Current, iVugust 10th to 2l3t, 

 1873, made the following observations on the Temperature of the sea at 

 different depths. From the Cape Verde Islands, 300 miles West of Cape 

 Verde, her track was in a general South-Easterly direction for 88 miles to 

 a position 150 miles S.S.W. of Sierra Leone ; thence, in the next two 

 days, she proceeded to a position 160 miles to the S.S.W., or 310 miles 

 from Sierra Leone. 



Temperature Observations, in Degrees f Fahrenheit), hy H.M.S. Challenger, 

 while crossing tiie Guinea Current, in August, 1873. 



The above Table, it must be remembered, refers to the time of year 

 when the Guinea Current is at its greatest power. Subsequently, in 

 returning home, the Challenger, in the passage from Ascension to the 

 Cape Verdes, in April, 1876, found the surface temperature in lat. 2° 30' S. 

 to be 821°; in 0° 15' S., 81^°. In lat. 3^ N., long. 15^ W., 300 miles S.W. 

 of Cape Mesurado, the temperature was 83° on the surface, in the same 

 position in which a temperature of 78° only was found in August, but the 

 warm water did not penetrate to so great a depth. At 50 fathoms, 65° was 

 found in August, but only 59° in April. Sir Wyville Thomson remarks : — 

 " "Where the rate of the current is highest, we have as usual a rapid fall 

 in the temperature below the surface. This is caused by the cooler water 

 rising to supply the place of the hot surface water, which is being rapidly 

 drifted and evaporated away." 



N. A. 0. 43 



