DEPTH OF THE OCEAN. 7 



Dr. Maury has also published many charts, giving the depths of the 

 ocean, the substance of which is given in the accompanying map, which 

 represents the configuration of the Atlantic up to the tenth degree of 

 south latitude, not in figures, as in Dr. Maury 's charts, but in tints ; 

 diagonal lines from right to left, representing the shores of both hemi- 

 spheres, indicate a depth of less than a thousand fathoms ; from left 

 to right, indicate bottom at one thousand to two thousand ; horizontal 

 lines, two to three thousand fathoms ; cross lines show an average depth 

 of three to four thousand fathoms ; finally, the perpendicular lines in- 

 dicate a depth of four thousand fathoms and upwards. Solid black 



Fig. 2. Chart of the Atlantic Ocean. 



indicates continents and islands; waving lines, surrounding both 

 continents at a short distance from the shore, indicate the sands which 

 surround the coast line at a little distance from the shore. 



The question may be asked, what useful purpose is served by taking 

 soundings at great depths? To this we may quote the answer of 

 Franklin to a question of similar tendency, addressed to aeronauts 

 "What purpose is served by the birth of a child?" Every fact in 

 physics is interesting in itself; it forms a rallying point, round which, 

 sooner or later, others will meet, in order to establish some useful 



