OBSERVATIONS ON THE TEMPERATURE AND 



SALINITY OF THE SEA AROUND THE CAPE 



PENINSULA. 



By J. D. F. GILCHRIST, M.A., B.Sc, Pn.D. 



It has been knowu for some time that the Cape of Good Hop© 

 presents many interesting problems with regard to the physical 

 condition of the sea in its neighbourhood. It is the meeting plac-e 

 of two great ocean currents, the warm equatorial current from tlie 

 Indian Ocean, (known on the East coa^t as the Mozambique 

 current, on the South as the Agulhas current,) and the cold 

 Antarctic drift current. These encounter each other not far from 

 the Cape Peninsula ; the greater portion of the Agulhas current 

 being turned baok again into the Indian Ocean, while a portion, as^ 

 shall be shown, escapes round the Cape Peninsula and proceeds up 

 the West coast. The Antarctic drift current is also split into two 

 branches as it encounters the projecting continent of South Africa 

 and into the fork so formed flows the warm equatorial current. 



This phenomenon is exhibited at each of the three great 

 continents projecting into the Southern Ocean, viz. : — South 

 America, South Africa and Australia, but in neither of the others 

 is it so well marked as in the second. 



The following observations are a contribution to our knowledge 

 of the phenomena associated with the meeting-place of the great 

 currents at the Cape Peninsula. It consists of four separate series 

 of observations, but these are more or less connected with each 

 other. They are : — First, a series of observations, made in March 

 and April, 1900, by the Government steamer Pieter Fcaire, of 

 temperatures at the surface and at about every ten fathoms, on a 

 survey to the West of the Peninsula, water samples being at the 

 same time collected and the amount of chlorine in grains per 

 gallon determined in the laboratory. In addition to these, obser 

 vations of surface temperatures were made on the ord March, 1898, 

 and llth-18th February, 1898, at intervals of about 5 miles, to a 

 distance of 50 miles West of Cape Town, and on a voyage to St. 

 Helena Bay. Second, daily records of air and sea temperatures 

 taken at Robben Island in liable Bay, and at Roman Rock in 

 Simon's Bay for a period of three years (1898, 1899 and 1900). 

 Third, tempejature observations and analyses of water sampler 

 taken at intervals on passages of the (iovernment trawler between 

 Table Bay and Simon's Bay, and of mail steamers between Table 

 Bay and Cape Hangklip, 



All these are parts only of a more extended scheme of observa- 

 tions now being carried out for the whole of the South African 

 coast, and are brought together here in the hope that they may 

 throw some light on the hydrographical phenomena in th& 

 particular region under considerotion 



B ^ 



