ii [ March 1st, 1887.] 



SCIENTIFIC NEWS. 



DEEP-SEA SOUNDING. 



WHEN our fathers, regardless of expense, made deep- 

 sea sounding-hiies of silk, they possibly thought 

 that the maximum limit of strength with a minimum of 

 weight had been reached. How far such a supposition 

 would be from the truth may be gathered when we re- 

 member that a cast of about four thousand fathoms has 



question which we need not stop to discuss now, but it may 

 be interesting to state, as the subject we are treating of de- 

 pends on the high tenacity of a steel wire, that Dr. Pole, in 

 a letter to Dr. Percy, the President of the Iron r.nd Steel 

 Institute, refers to a fine steel wire ('030 inch diameter) 

 which had the marvellous breaking strain of i69'9 tons to 

 the square inch. 



A material of such a tensile strength is only the product 



lllE SIGSBEE faOUNUI.NG MACHINE. 



been made with a line only twenty-eight thousandths of an 

 inch in diameter, and having a tensile strength of over 200 

 lbs. ; sometimes, indeed, being capable of supporting a 

 weight of 240 lbs. Of course there is but one substance 

 known from which such a line could be made, and that is 

 steel which has been subjected to the process ot wire-draw- 

 ing. The way in which the tensile strength of some metals 

 is increased by drawing through a die, as in the ordinary 

 process of making wire, is amongst those remarkable phe- 

 nomena which still remain for science to explain. It is a 



oi modern science skillully applied to a manufacturing in- 

 dustry, and the use of such a wire, even when made 

 for sounding purposes, has been surrounded by so many 

 difficulties, that mariners of a past generation may well 

 be excused for not having contemplated its use. 



To Sir William Thomson we owe this forward step in the 

 march of scientific investigation ; for it was in the Bay of 

 Biscay, in 1872, and from the deck of his schooner-yacht, 

 the La//a Rookh, that steel wire was first used for plumbing 

 the depths of the sea. We cannot do better than quote the 



