DEPTH OF THE OCEAN. 9 



line of soundings, the result of which is represented in the accom- 

 panying section, differed slightly from that followed by Lieutenant 

 Berryman. 



In the Gulf of Mexico, the depth does not seem to exceed seven 

 thousand feet ; the Baltic does not in any place exceed eleven hun- 

 dred. The depth of the Mediterranean is, as we have said, very variable. 

 At Nice, according to Horace de Saussure, the average depth is three 

 thousand three hundred feet. Between the Dalmatian coast and the 

 mouth of the Po, bottom is found at a hundred and forty feet. 

 Captain Smith found soundings at from one thousand to nine thou- 

 sand feet in the Straits of Gibraltar, and at ten thousand feet 

 between Gibraltar and Ceuta, where the breadth exceeds sixteen miles. 

 Between Ehodes and Alexandria, the greatest depth is ten thousand 

 feet. Between Alexandria and Candia it is ten thousand three hun- 

 dred. A hundred and twenty miles east of Malta it is fifteen thousand. 

 The peculiar form of the Mediterranean has led to its being compared 

 to a vast inverted tunnel. 



The Arctic Ocean has, probably, no great depth. Hence salt water, 

 following the general law of contracting as it is cooled until it freezes, 

 no ice can be formed on its surface till the temperature has fallen 

 through its entire depth nearly to freezing point, when the entire 

 mass is consolidated into pack-ice. According to Baron Wrangel, the 

 bottom of the glacial sea, on the north coast of Siberia, forms a gentle 

 slope, and, at the distance of two hundred miles from the shore, it is 

 still only from ninety to a hundred feet. Nevertheless, in Baffin's 

 Bay, Dr. Kane made soundings at eleven thousand six hundred feet. 



The inequalities of the basin of the Pacific Ocean are, comparatively, 

 unknown to us. The greatest depth observed by Lieutenant Brooke 

 in the great ocean is two thousand seven hundred fathoms, which he 

 found in fifty- nine degrees north latitude and one hundred and sixty- 

 six degrees east longitude. Applying the theory of waves to the billows 

 propelled from the coast of Japan to California, during the earth- 

 quake of the 23rd of December, 1854, Professor Bache calculated that 

 the mean depth of this part of the Pacific is fourteen thousand 

 four hundred feet. In the Pacific Ocean, latitude sixty degrees 

 south and one hundred and sixty degrees east longitude, he found 

 soundings at fourteen thousand six hundred feet about two miles and 

 a half. Another cast of the lead in the Indian Ocean was made in 



