550 



Dr. W. B. Carpenter on the 



[June 13, 



was still more explicitly set forth two or three years later by Prof. Buff, in 

 his " Physics of the Earth," as I showed in my First Report (1868, p. 187, 

 note) ; and although his experimental illustration was inappropriate, he 

 very clearly attributed the initiation of the movement to Polar Cold, rather 

 than to Equatorial Heat. It was not to this, as I shall hereafter show 

 (Appendix I., §§ 92, 93), but to the clearly untenable doctrine of Capt. 

 Maury, as to the production of the Gulf-stream and other sensible currents 

 by the elevation of level resulting from Equatorial Heat, that Sir John 

 Herschel's trenchant criticism applied ; and, as will presently appear, the 

 doctrine advocated in my last Report was explicitly accepted by him shortly 

 before his lamented death (§ 37). So that the general opinion of the most 

 eminent authorities in Physics may be fairly said to have been in favour of 

 the opinion which Mr. Croll dismisses as "a supposition very improbable." 



19. The facts on which I would lay most stress as justifying the pro- 

 visional acceptance of this doctrine, may be summarized as follows : — 



i. The marked horizontal division of the North Atlantic — the only open 

 Ocean of which the temperature has been yet examined by Serial Soundings 

 — into an upper Warm and a tower Cold stratum ; as shown by the rapid 

 descent of the thermometer in the M stratum of intermixture" between 

 them (§§ 5, 6). 



it. The entire absence of any such horizontal stratification in the water 

 of the Mediterranean (§ 7), as also in that of the Red Sea (§11) and of the 

 SuluSea(§ 12); the temperature of these Inland Basins, beneath the stratum 

 heated by direct insolation, being uniform down to their greatest depths. 



in. The prevalence of a Temperature averaging 52° at a depth of only 

 200 fathoms, and of 47° at 400 fathoms, in the Atlantic Ocean between the 

 Tropics (§8) ; where the water, even at these small depths, is lower in 

 temperature than at the greatest depths in the Mediterranean. 



iv. The prevalence of a Temperature only a few degrees above 32° over 

 the Deep Sea-bed of the North Atlantic generally (Report for 1869, 

 §§ 113-118), as also in the deepest parts of the Indian Ocean, not only to 

 the south (§10) but to the north of the Equator (Report for 1869, § 120), 

 and in the China Sea (§ 12) ; and the deep flow of Polar water, which, as 

 will be shown hereafter (§ 129), underlies the Gulf-stream from the Banks 

 of Newfoundland to the Florida Channel, and there passes beneath the 

 outflowing current into the Gulf of Mexico. 



v. The prevalence of a Temperature of from 32° to 29|° in the deeper 

 stratum of a portion of the " Lightning Channel " (§ 14) ; indicating, with 

 the Boreal character of the Fauna of that area, a S.W. underflow of glacial 

 water from the Arctic Sea. 



vi. The existence of a Temperature much warmer than the normal of 

 the Latitude, down to a depth of more than 500 fathoms, in another part 

 of the same Channel (§ 13), indicating a N.E. movement of the whole upper 

 stratum in this part of the Atlantic ; and the extension of that movement 

 as shown by Thermometric observation, into the Arctic Sea. 



