Physical Conditions of Inland Seas. 549 



phenomena of the Mediterranean present when compared with those of the Eastern 

 Atlantic, as will be seen in the following table : — 



SuLxi Sea. China Sea. 



deg. deg. 



83 surface 84 



— 



30 



fathoms ... 



... 77 



— 



40 





... 74 



— 



60- 



80 " 



... 71 



64-5 ... 



100 





... — 



— 



... 120 





... 62 







150 





... 66 



— 



... 200 





... 61 



— 



... 250 





... 4& 



51-5 ... 



... 308 





... — 



— 



... 416 





... 41 



50 



... 500- 



-1603 



... — 



— 



... 673- 



1546 



... 37 



Thus it appears that with a Surface -temperature almost exactly identical, and with 

 a rate of descent through the Sub-surface stratum which seems nearly the same, there is 

 a most marked difference beneath. For whilst, in the Sulu Sea, the thermometer 

 only falls from 61§° at 308 fathoms to 50° at 600 fathoms, and the temperature is 

 uniform from that point down to the bottom at 1,603 fathoms, the thermometer 

 undergoes a rapid descent in the China Sea from 49' at 250 fathoms to 41° at 416 

 fathoms, and thence to 37^ at 673 fathoms, at which point it remains stationary dowa 

 to the bottom at 1,546 fathoms. This difference is attributed by Capt. Chimmo, in the 

 Aiithor's opinion with adequate reason, to the exclusion from the Sulu Sea of the deep 

 Polar (Antarctic) current, which lowers the temperature of the China Sea. That the uni- 

 form temperature of its deep water from 500 fathoms downwards is lower by 4^ or 5"" than 

 that of the Mediterranean, notwithstanding that it is so much nearer the Equator that 

 the temperature of its superficial stratum is considerably higher, can be easily 

 accounted- for on the very probable supposition that there are passages between its 

 bounding reefs and islands, which admit water of a temperature below 50° from the 

 outside sea. In fact, we might fix the probable depth of such passages at about 250 

 fathoms. 



The influence of a still less complete seclusion from the Polar under-flow is shown 

 in the Celebez Sea, which has lately been found by Capt. Chimmo to have the ex- 

 traordinary depth of 2667 fathoms, with a bottom-temperature of 38^°; whilst at 

 nearly the same depth in the Indian Ocean a little to the west of Sumatra, the 

 bottom-temperature was 32°. And the land-locked condition of the Gulf of Mexico 

 seems to furnish the explanation of that extension of a high temperature to a much 

 greater depth than in ordinary Atlantic water, which is the distinguishing attribute 

 of the Gulf Stream; as the Author has shown in his Eeport of the ' Shearwater' 

 Scientific Ilesearches (Proceedings of the Eoyal Society, vol. xx. pp. 615-619). 



In his Eeport for 1870,^ in which year the Author's researches were confined to the 

 "Western basin of the Mediterranean, he described the fine muddy deposit which is 

 being formed over the whole of its deeper portion ; this probably consists mainly of 

 the minuter particles brought down by the Ehone, which appear to be diffused 

 through the entire mass of the water of the basin, and to be gravitating very slowly 

 to the bottom— the lowest stratum of water being everywhere rendered turbid by 

 their accumulation. Last year he found the same condition to prevail over the 

 bottom of the Eastern basin, the sediment having been there obviously brought down, 

 for the most part, by the Nile. This turbidity of the bottom-water appeared to him 

 to afford a rational explanation of the extreme scantiness of animal life on the deep 

 bottom of the Mediten-anean,^ which presented a most unexpected contrast to its 

 abundance, even at temperatures more than 20" lower, on the deep bottom of the 



and heavier stratum underlying the Gulf Stream comes nearer the surface with every rise of the 

 bottom over which it flows, I thinls it may fairly be presumed that the same cause is in operation 

 here also ; as it seems to be likewise in the " Lightning Channel " between the north of Scotland 

 and the Faroe Islands. 



1 Proceedings of the Koyal Society, vol. six. pp. 199-202. 

 • * His results on this point have been confirmed by the results of Oscar Schmidt's dredgings in 

 the Adriatic. 



