594 



Dr. W. B. Carpenter on the 



[June 13, 



within the Arctic area ; and he inferred, from the direction of the Iso- 

 thermal curves, that the influence of the Gulf-stream extends as far as 

 Nova Zembla*. 



90. The doctrine of the Gulf-stream as the efficient heater of North-western 

 Europe, and of the Sea that stretches from it towards the Pole, found an 

 enthusiastic and eloquent advocate in Capt. Maury. " There is," he says, 

 " a river in the ocean : in the severest droughts it never fails, and in the 

 " mightiest floods it never overflows ; its banks and its bottom are of cold 

 " water, while its current is of warm ; it takes its rise in the Gulf of Mexico, 

 " and empties into Arctic Seas : this mighty river is the Gulf-stream," — 

 which, he affirms, discharges over the Atlantic in a winter's day a quantity of 

 heat " sufficient to raise mountains of iron from zero to the melting-point, and 

 " to keep in flow from them a molten stream of metal greater in volume than 

 " the waters daily discharged through the Mississippi river ; " or as " suffi- 

 " cient to raise the whole column of atmosphere that rests upon France and 

 " the British Islands from the freezing-point to summer-heat." — Capt. 

 Maury, however, contests the doctrine originated by Dr. Franklin and 

 supported by Rennel, as to the propulsive force by which the Gulf-stream 

 is sustained : for instead of attributing it, like his predecessors, to the 

 action of the Trade-winds in driving the Equatorial Current into the Gulf 

 of Mexico, where, by the narrowness of its channel of exit it is converted 

 from a superficial c?n/if-current into a deep stream-current, he assigns it to 

 a combination of other agencies, the operation of which, however, he rather 

 indicates than distinctly specifies. Thus, he says, " modern investigations 

 " seem to encourage the opinion that this stream, as well as all the constant 

 " currents of the sea, is due mainly to the constant difference produced by 

 " Temperature and Saltness in the Specific Gravity of water in certain parts 

 " of the ocean. Such difference in specific gravity is inconsistent with 

 " aqueous equilibrium ; and to maintain this equilibrium these great cur- 

 " rents are set in motion. The agents which derange equilibrium in the 

 " waters of the sea, by altering specific gravity, reach from the Equator to 

 " the Poles ; and in their operations they are as ceaseless as heat and cold ; 

 " consequently they call for a system of perpetual currents to undo their 

 " perpetual work." Again, — " As for the seat of the forces which put and 

 " keep the Gulf-stream in motion, theorists may place them exclusively 

 " on one side of the Ocean with as much philosophical propriety as on the 

 " other. Its waters find their way into the North Sea and the Arctic 

 " Ocean in virtue of their specific gravity ; while water thence, to take 

 " their place, is, by virtue of its specific gravity and by counter-currents, 

 " carried back into the Gulf. The dynamical force which causes the Gulf- 

 " stream may therefore be said to reside both in the polar and in the inter- 

 " tropical waters of the Atlantic." 



91. The whole of Capt. Maury's reasoning on this point, however, is 



* "Ueber Linien gleicker Monatswarme," in Berlin Abhandl. (Phys.) 1848, p. 209 ; 

 and British Association Keport for 1848, p. 84. 



