626 



Dr. W. B. Carpenter on the 



[June 13, 



in July 1868, on the axis or northern border of the Gulf-stream. Thus 

 near the southern edge of the Grand Bank, the temperature of the surface 

 being 65°, it was found to be only 50° at 100 fathoms ; and a large iceberg 

 was met with as far as 30 miles south of the Grand Bank, showing the 

 southward extension of an underflow of Arctic water, although the surface- 

 temperature of 62° indicated that the upper stratum consisted of Gulf- 

 stream water flowing in a very different direction. " Although it was still 

 " 150 feet high, and nearly 400 immersed, it was quickly and perceptibly 

 " undermining, decomposing, splitting with loud reports, and floating 

 " away in large portions with the easterly current." In another instance, 

 the surface-temperature being 61°, the temperature at only 50 fathoms 

 depth was as low as 43° ; but there was here probably a mere overflow of 

 the surface-stratum, corresponding to that which extends beyond the " cold 

 wall" off the coast of the United States (§ 128). That there is still 

 a warm band extending to a considerable depth, seems to be indicated 

 by the sounding taken in Lat. 43° 30' N. and Long. 38° 50' W. to test 

 the existence of the supposed " Milne Bank." Here the surface-tempera- 

 ture being 73°, the temperature at 100 fathoms was 62°, and at 300 

 fathoms was 55° ; and thus, although the temperature of the upper stratum 

 was nearly ten degrees lower than that which it showed off Sandy Hook 

 (§ 128), the temperatures at 100 and 300 fathoms were nearly identical 

 with those there found at corresponding depths, and were above those 

 found at the same depths and under almost the same parallel nearer the 

 coast of Europe (§ 13). 



147. The direction of the Gulf-stream current is here so nearly due 

 East, that we should naturally look for its continuation across the open 

 Ocean in the same direction. After passing the meridian of 40° W., how- 

 ever, we find the summer Isotherm of 75°, which rises between the meridians 

 of 45° and 65° W. to the north of the parallel of 40° N., and the summer 

 Isotherm of 70°, which rises to 43° N., as well as the winter Isotherm of 

 60°, which nearly coincides with it, all tending southwards, — the first very 

 abruptly, the second and third more gradually (Plate VII.) ; and this ten- 

 dency corresponds with the general set of the surface-current. From the 

 coincidence of these facts, there can be no reasonable doubt that a very 

 large portion of the Gulf-stream here takes a Southward direction, passing 

 first S.E. towards the Azores, and then due S. and S.W., so as to return off 

 Cape Verde into the Equatorial Current, — thus completing, with the 

 North-African Current (§ 120), the "shorter circulation' 5 of the North 

 Atlantic. This deflection of the Gulf-stream current seems dependent 

 on an indraught, producing a " compensation-current" for the replacement 

 of the water driven westward by the Trade-winds. 



148. The question we have next to consider is, — What evidence can be 

 adduced of the extension of any part of the Gulf-stream proper, on the 

 Easterly line of direction which it retains on the Meridian of 40° W., to the 

 western coast of Europe ? It seems to be now clearly established that 



