8 



DEPTHS OF THE OCEAN 



depths greater than 300 fathoms. He was afterwards assisted 

 by his son, G. O. Sars, in carrying on this work, and in 1864 

 they gave a Hst of 92 species Hving in depths between 200 and 

 300 fathoms, and showed a few years later that marine Hfe was 

 abundant down to depths of 450 fathoms. 



In 1856 Mac Andrew pubHshed the results of his observations 

 on the marine Mollusca of the Atlantic coasts of Europe and 

 northern Africa, giving a list of 750 species obtained in his 

 dredgings, which covered 43 degrees of latitude. 



The oceanographical researches of the United States 

 Coast Survey may be said to date back to 1844, when the 

 Director, Bache, issued instructions to his officers to preserve 

 the deposit-samples brought up by the sounding-machine. 

 J. W. Bailey studied these deposit-samples, and published the 

 result of his examination in 1851, followed in 1856 by other 

 papers on deposits and on the formation of greensand in 

 modern seas. 



The name of M. F. Maury, of the United States Navy, was 

 for a long period associated with the hydrographical work of 

 the United States. He issued several editions of his Sailing 

 Directions to accompany the wind and current charts published 

 by the U.S. Hydrographic Office, the last edition appearing in 

 1859. About this time the need was felt for an improved and 

 more trustworthy method of sounding in deep water, and 

 various attempts were made to devise forms of apparatus to 

 replace the heavy weight attached to a line which had to be let 

 down and then drawn up to the surface again, the difficulty 

 being to know when the weight touched the bottom. This 

 problem was finally solved by Midshipman Brooke, who 

 conceived the idea of detaching the weight used to carry down 

 the sounding lead upon striking the bottom, the sounding tube, 

 enclosing its deposit-sample, being alone drawn to the surface. 

 He used a spherical weight (a bullet), with a hole passing 

 through the centre to receive the sounding tube, suspended by 

 a cord to the upper part of the sounding tube ; on touching the 

 bottom the cord was thrown off its support and remained at the 

 bottom along with the weight. With the aid of Brooke's 

 sounding apparatus, the records of deep-sea soundings rapidly 

 accumulated, and enabled Maury to prepare the first bathy- 

 metrical map of the North Atlantic Ocean, with contour-lines 

 drawn in at 1000, 2000, 3000, and 4000 fathoms, which was 

 published in 1854 and is reproduced in Map I. The deposit- 



