From Cape of Good Hope to Melbourne. 91 



H.M.S. " Challenger" left her anchorage in Simons Bay at 

 6.30 a.m., the 17th December, 1873. Between 10 and 11 

 a.m., she traversed a current of cold water with a surface- 

 temperature of 1 3 C, or 5 below the temperature recorded at 

 4 a.m. At noon the thermometer had again risen to i8°.3 C, 

 and at 3 p.m. to ic/.2 C. After sailing at midnight on the 

 following day through a second streak of cold water, the ship 

 crossed the northern limit of the Agulhas Current between 

 1 and 2 a.m. of the 19th December, at which time the surface- 

 temperature was observed to rise to 2 2°.2 C. Towards noon of 

 the same day, and at Station 143, distant about 150 nautical 

 miles from the Cape, the thermometer recorded the maximum 

 of 2 2 . 8 C. It next fell to 2 2°.2 C, and, with the exception 

 of a cold streak of 19 . 4 C. observed in the course of the 

 20th December, remained stationary until 2 a.m. on the 21st, 

 between which hour and 2.30 a.m. it fell from 2 2°.2 C. to 

 20°.6 C. This, then, was the southern limit of the Agulhas 

 Current, and the distance run between the two limits amounted 

 to about 250 miles. 



The existence of a streak of cold water in the opening of 

 Simons Bay and in the immediate vicinity of the Cape, agrees 

 with an explanation attempted by the author of the sudden 

 changes of temperature observed in Simons Bay, and of the 

 difference in the temperature of the water in the latter bay as 

 compared with Table Bay. It is contained in a short paper 

 published in The Cape Monthly Magazine for January, 1874, 

 edited by the late Professor Noble, and its substance may be 

 repeated here, as it furnishes a good illustration of the incessant 

 contest going on between the equatorial current of the Indian 

 Ocean and the polar current of the Southern Ocean, in the seas 

 off the Cape of Good Hope. 



The observations arranged in the following table were made 

 on board H.M.S. " Challenger," supplemented by Surgeon 



