630 report— 1884. 



the exact depths of the ocean, and bringing up parts of the soil from their beds, 

 may now be regarded as solved.' 



The deepest sounding known was taken by Belknap off the east coast of Japan, 

 4,655 fathoms, a little more than 5\ statute miles in depth. He took 304 soundings 

 of 1,000 fathoms or upwards, mean time of descent for the first 1,000 fathoms, 

 10 mins. 6 sees. ; lfcil of 2,000 fathoms or upwards, time of descent in the second 

 thousand, 11 mins. 86 sees. ; 38 of 3,000 or upwards, time of descent for the third 

 thousand, 12 mins. 46 sees. ; 9 of 4,000 fathoms or upwards, time of descent for 

 the fourth thousand, 15 mins. 54 sees. The rate of reeling in by hand was much 

 slower than now attained by the use of steam power, yet it was surprisingly rapid 

 and easy in execution in comparison with the reeling in of hemp line. 



In the great depths off the east coast of Japan, with the strong currents, 

 Belknap's appliances were in fact taxed beyond a perfectly satisfactory execution, 

 the wire having parted on one occasion at a depth of 4,643 fathoms, before reaching 

 the bottom, and again in reeling in, after sounding in a depth of 5} statute miles. 

 Larger wire and heavier apparatus can develope beyond a doubt the depths called 

 by the Germans the ' Tuscarora Deep.' As now supposed from the soundings 

 ■taken, this deep water lies at a mean distance of 120 miles from, and parallel to a 

 line drawn between the most easterly Cape of Niphon and the most northerly 

 Kurile Island. This is a general direction of N.E. half N. It appears to be at 

 least 250 miles in length, and is probably much longer. Captain Belknap justly 

 says that those extraordinary depths, contiguous to a region of elevations, afford a 

 field of operations of great interest to the hydrographer. 



The soundings made by Belknap comprise an arc of a great circle between the 

 northern part of the island of Niphon, the Aleutian Islands, and Puget Sound ; 

 another line between San Diego, Cal., via the Sandwich Islands, and the Bay of 

 Yokohama, and a development of the true ocean-bed from Puget Sound to San 

 Diego. They reveal a dozen or more submerged elevations, veritable mountains 

 ' full many a fathom deep.' In fact, these soundings furnish the first extended 

 and undeniable development of extraordinary and abrupt inequalities in the depths 

 of the sea far away from the land. We owe this to the inventive genius of Sir 

 William Thomson, and to the professional capacity of Captain Belknap, who not 

 only knew how to make the best use of what he was furnished with, but also had 

 the capacity to cure defects in the apparatus such as they were. In depths of 

 8,000 fathoms he used a detachable sinker of 55 lbs. In greater depths he supple- 

 mented this with 20 to 30 lbs. of lead. In order to secure specimens of the bottom 

 in larger quantity Belknap designed several cups, one of which is now unsurpassed 

 for efficiency by whatever modification or other design, as it did its work perfectly. 



Although at the time these soundings with wire were determined on, the 

 Superintendent of the Coast Survey of the United States hardly hoped a favourable 

 result from the use of wire, as it had not been adopted by the ' Challenger,' which 

 had been fitted out for scientific investigation some months before, yet so able a 

 man of science was not slow to adopt what Belknap had shown was so admirable. 

 In Sigsbee's ' Deep-sea Sounding and Dredging,' published by the Coast Survey, 

 Washington, 1880, we find, chap. 1, ' In August 1874 the " Blake," Commander 

 John A. Howell, U.S.N., was provided with one of Sir W. Thomson's sounding 

 machines for wire.' Commander Sigsbee in the following months made modifica- 

 tions in the apparatus giving additional facility and rapidity of execution in sound- 

 ing, .but nothing could be added to the accuracy of the results that had already 

 been obtained by Sir W. Thomson and Belknap. 



, .'In the soundings of the ('oast Survey, executed by Sigsbee, Bartlett, Tanner, 

 and others, we have a veritable revelation in the contours and depths of our 

 coasts. They have brought to our knowledge the wonderful cleft in the crust of 

 the earth on the line of the Hudson Iliver extending 100 miles beyond Sandy 

 Hook. Scarcely less interesting, but not so startling, are the plaster casts of the 

 Gulf of Mexico, and of the Caribbean Sea. It is a grateful duty to indicate to 

 whom honour is due that the depths of seas are no longer an unrevealed and un- 

 fathomable mystery. 



