ON THE COAST SURVEY, ETC., OF THE UNITED STATES. 257 



Among the earliest results of this work was the conclusion 

 reached by Dr. Carpenter in 1869, that there is practically no limit 

 to the depth at which animal life may exist in the ocean bed. 



This conclusion was based upon the results of dredgings made 

 during the " Porcupine " expedition, when the dredge was used at 

 a depth of 2,435 fathoms. Later researches have however, shown 

 that there is no life at the greatest depths, where the bottom 

 consists of a very fine ooze, almost entirely inorganic. Any remains 

 of pelagic organisms which may be presumed to live above it are 

 disintegrated and dissolved before they reach the abyssal depths. 



The " Challenger " was fitted with a fine collection of apparatus 

 for the purpose of dredging, but most of it was so heavy as to be 

 somewhat difficult to manage, especially at great depths. The more 

 recent introduction of the steel wire rope has enabled dredging to 

 be done with much smaller and lighter apparatus, and has also 

 enabled soundings to be obtained with much greater accuracy. 



Since the date of the " Challenger " expedition very little work of 

 the kind has been done by this country. The most important 

 recent investigations of the life and the physical conditions of the 

 sea have been conducted by the United States Coast and Geodetic 

 Survey, and by the United States Fish Commission. 



The former has been conducting observations along the eastern 

 coast of the United States, in the Carribean Sea, the Gulf of Mexico, 

 and adjacent waters, the steamer tl Blake," fitted with the most 

 perfect apparatus yet devised for the purpose, having, under the 

 direction of Professor Agassiz, been almost continually engaged in 

 the work during the past four years or more. 



The Fish Commission has also accomplished much valuable 

 work in studying the natural history and habits of the fishes and 

 other animals living in the United States waters, conducting 

 physical investigations, and in many ways contributing largely to 

 our stock of knowledge. Some interesting observations on the 

 temperature have been made by Professor Verral. 



Although the United States Government fitted out a smaller vessel 

 than the " Challenger " for their investigations, they have continued 

 the work for a much longer time, and one of the results of this is 

 that they have a good series of specimens of sea bottom along the 

 whole coast as far as the State of Maine, as well as a series of 

 observations on the Gulf Stream. On the western border of the 

 Gulf Stream a new fish has been found, the so-called " Tile-fish. " 



