CUEEENTS ON THE SOUTH AFEICAN COAST, 

 AS INDICATED BY THE COUESB OF DEI FT 

 BOTTLES. 



By J. D. V. GILCHRIST, M.A., B.Sc, Ph.D. 



rrovernrment Biologht to the Colony of the Cape of Good Hope. 



Paht I. 



The following is a record oi the course of a number of drift 

 bottles sent off at various localities in the sea surrounding the 

 South African coast. 



The method adopted was simply to drop into the sea a small 

 bottle (2 oz.) containing a card with a request to the finder to re- 

 turn it, after noting the locality and time at which the bottle 

 was found. Such a method of testing currents, of course, raises 

 the obvious objection that a record is got more of wind direc- 

 tion than of sea currents. This objection has already been 

 discussed elsewhere, and it need only be repeated that while it 

 is to a certain extent valid, yet, in view of the fact that the 

 bottles when afloat are fairly well submerged, and that the 

 winds themselves are the chief causes of all surface currents, 

 we cannot but attach considerable importance to the results 

 of such experiments. Moreover, we shall produce some direct 

 evidence that the course taken at least in one case was to be 

 attributed more to current than wind. Of particular interest 

 in this respect is the directions taken by bottles Nos. 108, 296, 

 316, and 318, the last two being set off in practically the samo 

 place and at the same time, yet, apparently, taking quite 

 opposite directions. 



The bottles consist of two series, viz.: — First, those set off 

 at fairly regular intervals, and at fourteen definite points along 

 the coast between Cape Town and Natal, from the mail steamers. 

 At the request of the Meteorological Commission of Cape 

 Colony the Union-Castle Steamship Company most willingly 

 undertook to assist in the investigations, and the results, of 

 which only a part is here reported on, are of special value on 

 account of their regularity. The bottles set off in this way 

 were numbered consecutively, and are distinguished here by 

 the addition of the letter " MV' That no confusion might arise 

 the card enclosed in the bottle was of a different colour from 



