DEEP-SEA DEPOSITS. " 547 



wait more than sixteen years for it. They had however already par- 

 tially satisfied the impatience of the world of learning- by publishing 

 the principal results as separate memoirs. 



Mr. John Murray, on board the exploring ship, had the duty of col- 

 lecting, examining, preserving, and classifying all the specimens brought 

 to the surface by soundings or the dredge, and of making all the notes 

 relating to their derivation. Since his return to England this scientist 

 has devoted himself entirely to the examination of this large quantity 

 of material. 



In 1878 Sir Wyville Thomson* and Mr. Murray were happily led to 

 ask the collaboration of the eminent Belgian ijetrologist, the Abbe 

 Renard, jjrofessor at the University of Ghent, whose microscopic inves- 

 tigations of rocks had already contributed much to the progress of 

 science, and had secured him special authority in that study. 



Among thedififlculties presented to these gentlemen were the tenuity 

 of the dusts, often extreme, the almost constant fragmentary form of 

 the particles, and the change in their nature, effected by the chemical 

 action of the sea. 



In another j)ortion of the work Mr. Eenard had given a description 

 of the rocks, mostly of a volcanic nature, collected in the Oceanic 

 Islands, and had determined with precision their crystalline elements.t 

 These rocks were to serve as terms of comj)arisou with the debris of 

 the same nature which occupies so large a sjiace in the great ocean 

 depths. 



In addition to the collections of the Challenger, Messrs. Murray and 

 Eenard had at their disposal the sediments gathered by several other 

 English expeditions. Prof. Mohn, of Christiana, gave them the deposits 

 dredged in the North Atlantic by the iS^orwegian expedition, whose 

 beautiful and important publications are known to all naturalists. 

 Besides these, the Coast Survey of the United States and Mr. Alex- 

 ander Agassiz consigned to them a series of specimens of soundings, 

 obtained by various American ships. Thus, the material gathered by 

 almost all the sub-marine explorations, were used in the investigations, 

 the results of which we are about to consider. 



The two great French expeditions, vso well known from their splendid 

 discoveries in the deep seas, are not spoken of in this article, because 

 they were of a subsequent date to that of the Challenger and because 

 their i)nrpose was essentially zoological. That of the Traraillenr was 

 from 1880 to 1882, and that of the Talisman in 1883. Of the studies 

 made by Albert First, sovereign prince of Monaco, the first date from 

 1885. 



Before noting the discoveries relative to the great depths of the sea, 

 it is well to recall in a succinct manner the knowledge already possessed, 



* Sir Wyville Thomson died in 1882. 



tReport on the Petrology of Oceanic Islands, 1889 1 180 pages, 7 maps, and numerous 

 diagrams. 



