380 THE SCIENTIFIC PAPERS OF 



the bathometer would warn the commander of a vessel of the 

 gradual approach of shallow water ; and if in possession of 

 accurate charts, he would in many cases be able to determine 

 his actual position by noting in which direction and at what rate 

 the depth varies. 



POSITION OBTAINED BY SOUNDINGS. An illustration from 

 actual practice may serve to show how accurate a guide a know- 

 ledge of the depth of the sea can be made. In laying the Direct 

 United States Cable to America, of which operation Mr. Carl 

 Siemens took the principal charge, it occurred that, in November, 

 1874, heavy weather had prevented the taking of observations for 

 three days, when an increasing gale, and the suspicion of a slight 

 fault having passed overboard, rendered it necessary to cut the 

 cable and buoy the end. Before cutting the cable a sounding was 

 taken by Sir William Thomson's wire, and the depth was found to- 

 be 800 fathoms. The gale lasted several days ; and when the 

 " Faraday " returned to the spot where the end was supposed to- 

 be buoyed, no buoy could be found, and it became evident that it 

 had been torn away from the anchor-chain by the violence of the 

 gale. The sounding taken at the point where dead-reckoning had 

 placed the ship at the time of buoying the cable gave a depth of 

 521 fathoms, lat. 48 32' N., long. 45 21' W., and showed at 

 once that the end of the cable must be looked for elsewhere. 

 There exists no chart of the part of the Atlantic in question, 

 giving such soundings as might have assisted in the search ; but 

 special soundings were taken in all directions, from which the dip 

 of the Atlantic basin in that locality could be ascertained. The 

 cable was parted over a depth of 800 fathoms ; and in construct- 

 ing the contour-lines of the Atlantic basin in the locality, which 

 was dipping towards the N.E., it became evident that in order to 

 obtain the cable with the grapnel, it must be caught up in a line 

 parallel to the contour-line, but a mile or two to the eastward. 

 The expedient adopted proved successful, and the cable was 

 recovered in lat. 48 44' N., long. 44 J 44' W., or at a point 25 

 nautical miles removed from the place where it was supposed to 

 have been lost (see Plate 30, fig. 3). If complete information 

 regarding the depth of the Atlantic Ocean had been available in 

 laying the cable, and if the steamship " Faraday " had at that 

 time been furnished with a reliable bathometer, the uncertainty 



