38 



Prof. W. Thomson on the 



[Nov. 18, 



water of the ocean at any one place is due, in a great measure, to the tempe- 

 rature of the source of that water — not entirely due, for in passing through 

 a long distance the temperature of even the greatest masses of water is 

 certainly gradually altered by conduction and mixture. 



The suggestions of Dr. Carpenter and Mr. Buchanan that the existence 

 of a deep layer of warm water in the Atlantic might be connected in 

 some way with the mean annual temperature of the area and the absence 

 of ocean-currents, are very suggestive ; and I looked forward with great 

 interest to an opportunity of testing them in the corresponding position 

 in the Pacific. But there seems to be no trace of any thing of the kind ; 

 as the influence of the equatorial reflux becomes weaker the temperatures 

 fall uniformly. 



To show that the conditions in the two oceans differ more in degree 

 than in kind, I give in Plates 3 and 4 curves constructed from serial 

 soundings along nearly corresponding lines in the Atlantic and Pacific. 

 Curves A and B are added on Plate 3 to show the position of the deeper 

 belt of abnormally warm water which makes its appearance near the 

 coast of Europe. 



Plate 3. 

 North- Atlantic Ocean. 



No. of 

 Station. 



Latitude. 



43 36 23 N. 



44 37 25 „ 



53 36 30 „ 



65 36 33 „ 



69 38 23 „ 



71 



80 



38 

 35 



18 

 3 



Longitude. 



71 si w. 



71 40 „ 



63 40 „ 



47 58 „ 



37 21 „ 



34 48 „ 



21 25 „ 



A A In the Bay of Biscay. 



B B Off the coast of Portugal. 



Plate 4. 

 North-Pacific Ocean. 



No. of 

 Station. 



237 

 240 

 243 

 245 

 246 

 248 

 252 



Latitude. 



34 37 N. 



35 20 „ 



35 24 „ 



36 23 „ 



36 10 „ 



37 41 „ 

 37 52 „ 



Longitude. 



140 32 E. 

 153 39 „ 

 166 35 „ 

 174 31 „ 

 178 „ 

 177 4W. 

 160 17 „ 



Depth in 

 fathoms. 



1700 

 2650 

 2700 

 2200 

 1675 

 2660 

 2090 

 1090 



Depth in 

 fathoms. 



1875 



2900 

 2800 

 2775 

 2050 

 2900 

 2740 



There seems to be little doubt that the enormous mass of cold water 

 which fills up the trough of the Pacific is, like the cold bottom-water of 



