1870.] 



Deep-sea Researches. 



185 



been noticed on the outward voyage on entering it (§ 30). This change 

 proved to be very decided. As we kept along the Southern Coast of Por- 

 tugal towards Cape St. Vincent, the Surface-temperature averaged 73 0, 5. 

 At 6 p.m. we were turning the corner of the Cape, and found the Surface- 

 temperature 72°'5 ; and at 8 p.m., when we were fairly in the Atlantic, 

 we found that the Surface-temperature had fallen to 69°, thus showing a 

 difference of 4°'5. On the following day, when we were off Lisbon, the Sur- 

 face-temperature was 69°'5 ; and it gradually diminished as we proceeded 

 Northwards from that point. — Although the season of the year led us to 

 expect a rough passage across the Bay of Biscay, the weather continued 

 remarkably fine until we reached the " Chops of the Channel," where we 

 fell in with a rather fresh breeze ; this did not interfere, however, with our 

 anchoring at Cowes on the afternoon of the next day (Oct. 8th), after an 

 absence of just two months, during which a greater number of most im- 

 portant Public events had occurred than had ever before been crowded 

 within so short a period. 



GENERAL RESULTS. 

 Temperature and Composition of Atlantic Water. 



[For this portion of the Report Dr. Carpenter is alone responsible.] 



73. Surface-Temperature. — The Temperature of the surface-water at 

 the Chops of the Channel (Stations 1-9) averaged 62° for five days ; and 

 it rose gradually in conformity with the Southing, until at Cape St. Vincent 

 it stood at 69°. The Temperature of the Air, which averaged 63°*4 in the 

 former locality, rose to about 69° in the latter ; but it is specially note- 

 worthy that whilst, as we crossed the Bay of Biscay and drew southwards 

 along the coasts of Spain and Portugal, the temperature of the Air was 

 almost always higher by from 2° to 5° than that of the Sea, this difference 

 ceased to show itself as we neared Cape St. Vincent, and was even replaced 

 by a slight difference in the contrary direction. The excess in the Surface- 

 temperature of the Sea above the temperature of the Air became still more 

 marked after we had passed the Cape, and had changed our course to the 

 East ; a sudden rise of from 2° to 4° then showing itself in the former, 

 whilst the latter did not rise by more than half that amount. Thus on 

 July 30, between Stations 27 and 28, on our way to Cadiz, in about 

 Lat. 36|° N. and Long. 7J° W., the surface-temperature of the Sea exceeded 

 74°, whilst the temperature of the Air was only 72°. The like condition 

 showed itself after leaving Cadiz, on August 2, between Stations 29 and 30 ; 

 the surface-temperature of the Sea being 73°*2, whilst the temperature of 

 the Air was 71°*4. That this excess did not depend upon a reduction of 

 evaporation, consequent upon a peculiarly damp condition of the atmo- 

 sphere, appeared from the fact that the Wet-bulb thermometer during this 

 period stood at from 3° to 4° below the Dry a difference fully equal to 



