32 A Retrospect of Oceanography 



ice-cold temperature until it was emptied on the bridge. An 

 ordinary thermometer plunged into it showed a temperature 

 almost exactly the same as that given by the registering thermo- 

 meter on the sounding-line. Indeed, I think that it was in 

 the first dredgeful of red clay that Professor Wyville Thomson 

 cooled a bottle of champagne to celebrate the discovery at 

 dinner. Similar observations were made on the way from 

 St Thomas to Bermuda. 



By this time it had been firmly established that the nature 

 of the deposits in the open ocean varies in a definite way 

 according to the depth of the water. Between 1000 and 1500 

 fathoms the predominant constituent was the pteropod shelL 

 At greater depths they disappeared, and the calcareous portion 

 of the mud consisted of the shells of foraminifera up to a depth 

 of about 2500 fathoms. Beyond this depth the foraminifera 

 rapidly disappeared, and at a depth of over 3000 fathoms 

 the mud consisted almost entirely of red ochreous and argil- 

 laceous matter. 



Bermuda island, separated from the nearest land by 600 

 miles of sea of over 2500 fathoms depth, consists entirely 

 of the debris of marine calcareous shells bedded mostly under 

 the influence of the wind. The island, however, is covered 

 with a rich soil, and in many places between the calcareous 

 beds there were layers of red earth. Professor Thomson was 

 much struck with this occurrence, and it suggested to him 

 an analogy with the distribution of the calcareous and the 

 earthy matter at the bottom of the ocean. The disappearance 

 of the calcareous matter with increasing depth had already 

 been attributed to solution in passing through a greater amount 

 of water ; and it was natural that the thin and delicate pteropod 

 shells should disappear before the smaller and stouter globi- 

 gerinae. 



Professor Thomson imagined that a similar action had 

 taken place in the calcareous beds of Bermuda under the action 

 of the rain, which removed the carbonate of lime, leaving the 

 red clay as a species of "ash." It was here supposed to have 

 formed an integral portion of the substance of the shells, which 

 thus consisted partly of carbonate of lime and partly of the 



