418 OBSERVATIONS ON THE CURRENTS. 



beyond longitude 60°. This adds very much to the complexity of the 

 problem of how the warmer waters of the Gulf Stream can possibly reach 

 the coasts of N.W. Europe, as strenuously claimed for them by some. 

 The Northern margin is known to be in a continual struggle with the 

 Arctic Current, which sets at right angles to its course with about an equal 

 velocity ; and, therefore, a mere verbal account can give but little definite 

 information.* 



With this uncertainty about its limits or existence in some parts, it is 

 evidently difficult to estimate its breadth ; but, according to the generally 

 received extent, it may be about 300 or 350 miles on the meridian of 

 48° W., a most vague amount, but which makes it about eight times the 

 breadth that it was in the Narrows of Florida ; and, as its mean velocity 

 is less than one-half of what it was at the commencement, it follows that 

 the whole body of water passing Florida will not be more than 20 or 25 

 fathoms deep over such a line ; and, as its temperature is lower on the 

 surface at the Eastern part of the course in question than it was at its 

 commencement, it follows that the film of warm water it sends up here 

 cannot be more than a few inches in thickness. The area supposed to be 

 covered by it between Nantucket and long. 48° W. is not less than 

 280,000 square miles ; and, therefore, 240-7 cubic miles (see page 414) 

 poured over this per diem will make a stratum of about 5^ feet thick per 

 diem. If the larger figures of the American observers on this point be 

 accepted, or about 850 cubic miles per diem, the addition to the thickness 

 of the stratum does not amount to much. 



Temperature. — There is one singular fact — elicited by later researches, 

 and by a comparison with the Current Charts of the Meteorological Ofl&ce 

 — which is, that the main body of the warm water, which has been traced 

 along the United States coast, bears off in a due Easterly course South- 

 ward of the parallel of 38° N. — that is, directly across the ocean (not on a 

 Great Circle course, but to the Southward of it) toward the Strait of 

 Gibraltar ; and this, too, where there is not the slightest evidence of an 

 Easterly Current on the former monthly or annual mean charts of the 

 Currents. This is very remarkable, and well deserves attention from those 

 who study the distribution of Ocean warmth. There can be no doubt of 

 the fact, since Maury, Rennell, Andrau, and the Meteorological Office, all 

 agree on the point. 



(409.) The late Dr. Petermann, who gave an immense amount of study 

 to the subject, drew up two charts to illustrate his views, taken from the 

 mean values of Maury's and other charts, for the months of July and 

 January. On the July chart, the core of the Gulf Stream {Kern des Golf- 

 stroms) shows the form of a tongue, of a temperature of 81-5^ (at some 

 places even 84° was observed), extending North of the Equator to the 

 38th degree of latitude. This may be called not only a warm, but, better, 

 a hot stream. This hot stream thence continues as a double tongue, with 

 a mean temperature of from 77° to 81-55° towards the North as far as the 

 40th degree of latitude (in one spot only), and towards the East to the 43rd 



• At times the change from warm to cold surface water is very marked. Commander 

 Chimmo found it deocaase in going Northward, from 72° to 58° in 2J hours. 



