GI: ANNUAL OF SCIENTIFIC DISCOVERY. 



Third : There being no strain upon the line in the descent, and the motion 

 being uniform, it is practicable to determine the depth by the time of descent, 

 making use of a small insulated wire as a sounding-line, and determining 

 the instant that the weight strikes the bottom by an electrical signal trans- 

 mitted through the line. An apparatus was devised as long since as the 

 year 181-5, for ascertaining the moment when the weight strikes the bottom, 

 by electricity; but in the mode of sounding heretofore employed, no par- 

 ticular advantage would result from this, while the danger of breaking the 

 electric continuity is very great, owing to the strain brought upon the line 

 in the descent. And the plummet, as now used, descends with such a vary- 

 ing velocity, that, even with the time of descent given, no calculation will 

 give the depth. The method has therefore never been put in practice. 

 Whereas, in the method proposed, there is no strain upon the line in its 

 descent, and the plummet will fall through each successive hundred fathoms 

 in the same time; the time of descent will thus furnish a simple means of 

 calculating the depth. 



In this process it will not be necessary to recover the line, and the time 

 required to sound the ocean at any point, need only be that required for the 

 plummet to sink to the bottom, moving with any velocity Avhich may be 

 desired. 



Many experiments have been made on the best method of coiling the line 

 so as to secure its uncoiling with certainty, and without the possibility of 

 strain upon the line, or the occurrence of a kink. 



Much attention has also been given to the quality and size of line to be 

 used. Upon these points the practical working of the apparatus in a certain 

 degree depends; but, being merely mechanical questions, they are easily 

 settled. 



The importance of the problem which is thus sought to be solved, in con- 

 nection with the survey of the coast, has never been questioned. A knowl- 

 edge of the configuration of the bottom of the sea, adjacent to the coast, is 

 necessary to the solution of many questions of importance to navigation 

 and to science, and especially that of the ruling feature of the Atlantic coast, 

 the Gulf Stream. But besides these considerations, the question has become 

 one of great public interest, in connection with the laying of submarine tele- 

 graphs, the risk of such enterprises being diminished in proportion to the 

 accuracy with Avhich the depth of the sea is known at every point of any 

 proposed line, and the ultimate practicability of such operations across the 

 Atlantic being yet to be demonstrated by new and more accurate soundings. 



EXPERIMENTS WITH BELTING. 



It has long been a question of great interest to all who use belting to drive 

 machinery, whether leather or vulcanized rubber hugged the pulley the best, 

 and hence was less liable to slip. To satisfactorily determine this question, 

 Mr. J. H. Cheever, of New York, has instituted a series of experiments, by 

 means of a simple device of three pulleys, which we may designate as B, C, 

 and D, mounted on an axle or shaft in a frame. Pulley B was covered with 

 rubber; C was a polished iron pulley, such as is ordinarily used in machine- 

 shops; and D was covered with leather. In the first experiment, a leather 

 belt of good quality, three inches in diameter and seven feet long, was placed 

 over the pulley, with thirty-two pounds suspended from each end. Weights 

 were then added at one side until it began to slip over the pulley, and the 

 results were as follows : 



