312 ANNUAL OF SCIENTIFIC DISCOVERT. 



9 24 45 



The whole, time therefore, taken by the plummet in descending 

 through 7706 fathoms, or nearly 7.7 geographical miles of 60 to the 

 decree, was 9 h 24 m 45 s . The highest summits of the Himalaya, Dha- 

 walagiri and Kinchinginga, are little more than 28,000 feet, or 4.7 

 geographical miles above the sea. The sea-bottom has therefore 

 depths greatly exceeding the elevation of the highest pinnacle above 

 its surface. 



The strength of the line tried before the sounding was found to be 

 equal to bear 72 pounds in air. The 7706 fathoms which ran out 

 weighed, when dry, 77 pounds, exclusive of the plummet, 9 pounds. 

 Great care was taken in the endeavor to bring the plummet again to 

 the surface to show the nature of the bottom, but, whilst carefully 

 reeling in, the line broke at 140 fathoms below the water-line, carrying 

 away a Six's thermometer which had been bent on at 3000 fathoms. 



During the past summer, the United States brig Dolphin has been 

 engaged in Atlantic explorations under the direction of Lt. Maury. 

 Sailing from the Chesapeake Bay his first task was, to strike a line 

 from that bay to Rockule, on the west coast of Scotland, and take 

 soundings at intervals of a hundred miles along it. From Rockule a 

 second line was run to the Azores ; a little to the north of which a 

 ridge, 6,000 feet in height from the ocean bed, was discovered, the 

 soil on this elevation being a fine yellow, chalky substance, mixed 

 with fine sand. From the Azores the explorer made a westerly cut, 

 everywhere finding bottom, and everywhere noting the set of tides 

 and currents, and the temperature of the water. The Dolphin next 

 steered for the Three Chinmies, where she found bottom at a depth 

 of 1,900 fathoms. The greatest depth of water was found in lat. 41 

 to 43, long. 51 to 56, where the line fell out 3,130 fathoms. The 

 Dolphin is to continue her observations on the eastern side of the 

 Azores. She is admirably fitted for her work, and possesses the finest 

 sounding apparatus hitherto constructed. Hitherto a continuous se- 

 ries of soundings in deep water has been rendered difficult by the 

 fact of each sounding costing the ship a fresh line ; however strongly 

 the line was made, when once out it has never been recovered. A 

 method has, however, been invented by which the weight on touching 

 the bottom is detached, so that the line may be drawn back with ease. 

 This is effected in the following manner. A hole is drilled through a 

 64 Ib. or heavier shot, sufficiently large to admit a rod of about three- 

 quarters of an inch in diameter. This rod is about 12 or 14 inches in 

 length, and with the exception of about 1 inch at the bottom, per- 



