From Hong-kong to the Admiralty Islands. 107 



2800 fathoms, forming a stratum of more than two miles in 

 thickness of the uniform temperature of 3° C. The existence of 

 this stratum seems to prove that if the Banda Sea has any deep- 

 sea communication with the Indian Ocean — of which there are 

 certain indications in the deep soundings of 2005 and 2320 

 fathoms found by the " Gazelle " close to and north of the 

 island of Timor — the depth of the channel or channels which 

 connect the two oceans cannot exceed 900 fathoms. At Station 

 195, between Banda and Amboina, 4400 fathoms of dredge- 

 rope were paid out in anticipation of a depth of 4000 fathoms, 

 marked in the older charts, but the depth turned out to be only 

 1425 fathoms (bottom temperature, 3° C.) — a further proof of how 

 little reliance can be placed on soundings taken with the imper- 

 fect appliances formerly in use. 



The Molucca Passage. — The bottom temperature of i°.8 C, 

 registered in a depth of 1200 fathoms at Station 197, contrasts 

 remarkably with the temperature of the corresponding depth in 

 the Banda Sea ; and a comparison of the isotherms of this station 

 with those of Station 214 and Station 215, at the entrance of the 

 Molucca Passage, establishes the deep-sea communication 

 between this passage and the North Pacific. 



The Sea of Celebes. — This sea forms another of those 

 areas of narrow superficial extent, but of great depth, so charac- 

 teristic of the Indian Archipelago. The several soundings of 

 H.M.S. "Challenger" give depths of 2150, 2600, and 2050 

 fathoms, with bottom temperatures respectively of 3°.; C, 3°. 5 C, 

 and 3° C. The decrease of temperature is arrested at a depth of 

 800 fathoms with a temperature of 3°.; C. The line of islands 

 between Celebes and Mindanao, therefore, forms an effectual 

 barrier against the inflow of colder water from the Pacific. 



The Sulu Sea. — The portion of this sea in the immediate 

 vicinity of the east coast of Mindanao forms a deep hollow, with 

 depths of 2225 and 2550 fathoms, and furnishes, with the Medi- 



