From Station 253 to Station 288. 117 



ing the meridian of long. 180°, we pass into the thermal area 

 of the North-Eastern Pacific. 



Section from Station 253, along the Meridian of Hono- 

 lulu and Tahiti, to Station 288 (Plate 19, Table XIII.). — 

 Embracing nearly 80 degrees of latitude, and extending along a 

 track of considerably over 5000 nautical miles divided into 35 

 stations, this section, surveyed in the third year of the " Chal- 

 lenger" cruise round the world, is a lasting- monument of the 

 skill and perseverance of the officers and men of the old English 

 frigate. 



A minute examination of the section could only lead to an 

 unnecessary repetition of much that has been said in connection 

 with the other sections. With the assistance of the sketch given 

 in previous chapters of the leading phenomena of oceanic circu- 

 lation, it will not be difficult to arrive at the principal facts 

 connected with the distribution of temperature in the Pacific 

 Ocean, viz. : The warm surface-stratum between the parallels of 

 lat. 30° N. and lat. 30° S., the "cold wall" between the 35th 

 and 40th parallels, and the gradual warming of the intermediate 

 strata indicated by the spreading out of the isotherms from the 

 equatorial belt towards the 35th parallel. 



A comparison of the Atlantic section (Plate 9) with the 

 Pacific section (Plate 19) brings out the principal contrast 

 between the two oceans. While the North Atlantic basin is 

 considerably warmer than the South Atlantic basin, we observe 

 the contrary in the Pacific Ocean ; or it would be more correct to 

 say that the South Pacific is warmer than the South Atlantic, 

 and the North Pacific colder than the North Atlantic, since the 

 two sections do not afford a fair comparison between north and 

 south in the two oceans. The differences observed between the 

 Atlantic and the Pacific are due chiefly to the great difference 

 between their respective areas. Owing partly to the projection 

 of the South American coast at Cape S. Roque into the com- 



