254 THE PHYSICAL GEOGRAPHY OF THE SEA. 



steppes and mountains, extending across that continent from west 

 to east, and disappearing on the shores of the Pacific. We do 

 not know how it is at the bottom of the " Grand Ocean," but the 

 chain of Aleutian islands, rising out of the water midway between 

 Asia and America, seem to suggest that it is there also. How- 

 ever, if we run the eye along to America, we shall perceive again, 

 as soon as we come to this continent, indications of this ridge, 

 which here divides the waters that flow north from those that seek 

 the ocean in more southern latitudes. 



716. It was upon this ridge or plateau, as it crosses the Atlan- 

 tic, that Brooke's sounding apparatus brought up its first trophies 

 from the bottom of the sea. These specimens Lieutenant Berry- 

 man and his officers judged to be clay ; but they took the precau- 

 tion to label them, carefully to preserve them, and, on their re- 

 turn to the United States, to send them to the proper bureau. 

 They were divided : a part was sent for examination to Professor 

 Ehrenberg, of Berlin, and apart to Professor Bailey, of West Point 

 — eminent microscopists both. I have not heard from the former, 

 but the latter, in November, 1853, thus responded : 



717. " I am greatly obliged to you for the deep soundings you 

 sent me last week, and I have looked at them with great interest. 

 They are exactly what I have wanted to get hold of. The bottom 

 of the ocean at the depth of "inore than tico miles I hardly hoped 

 ever to have a chance of examining ; yet, thanks to Brooke's con- 

 trivance, we have it clean and free from grease, so that it can at 

 once be put under the microscope. I was greatly delighted to 

 find that all these deep soundings are filled with microscopic 

 shells ; not a particle of sand or gravel exists in them. They are 

 chiefly made up of perfect little calcareous shells {Fo7Xi')niniferoe), 

 and contain, also, a small number of silicious shells {DiatomacecB), 



"It is not probable that these animals lived at the depths where 

 these shells are found, but I rather think that they inhabit the wa- 

 ters near the surface ; and when they die, their shells settle to the 

 bottom. With reference to this point, I shall be very glad to ex- 

 amine bottles of water from various depths which were brought 

 home by the Dolphin, and any similar materials, either ' bottom,' 

 or water from other localities. I shall study them carefully 



