OCEANIC CIRCULATION. 229 



some currents must necessarily be submarine. For 

 instance, the quantity of water carried by the great 

 north-easterly drift into the Arctic Ocean is very much 

 greater than that which flows out of the Arctic Ocean, 

 by the so-called Arctic current, past Greenland. Ex- 

 amining, indeed, the ordinary current charts, always 

 drawn on Mercator's projection (seemingly because this 

 projection is the very worst that could be devised for 

 the purpose), we might suppose that this arctic stream 

 was much more extensive than it really is. But what 

 can be expected of a projection which makes Green- 

 land (whose real area is not much greater than that of 

 the Scandinavian peninsula) actually as large as South 

 America. The Arctic current, however, affords yet 

 better evidence of the occurrence of submarine streams, 

 for the extension which passes between the Gulf Stream 

 and the United States, is in places completely lost 

 sight of (the Gulf Stream touching the American 

 shores), and reappears farther on. It is clear that 

 it must have passed under the Gulf Stream in such 

 cases. 



Now, the study of the submarine currents has of late 

 years thrown considerable light on the whole question 

 of oceanic circulation, and has supplied the solution of 

 some problems which had formerly appeared altogether 

 perplexing. 



We owe to Drs. Carpenter and Wyville Thomson 

 some of the most important facts recently ascertained. 

 Others, however, have shared in the work. I would, 

 indeed, particularly invite attention to the fact that I 



