NAVIGATION. 51 



only reduce speed when he cannot, at full speed, 

 take the soundings required for safety. 



36. I have shown elsewhere l that the labour of 

 taking deep-sea soundings, whether for surveys of 

 the ocean's bed, or for guidance in cable laying, 

 or for ordinary navigation, may be immensely 

 diminished, and the quickness, sureness, and 

 accuracy of the operation much increased by the 

 use of steel pianoforte-wire instead of hemp rope. 

 You see before you a first rough attempt at an 

 instrument for ordinary navigational sounding by 

 pianoforte wire. I have tested its efficiency off 

 the Island of Madeira, and off Cape Finisterre, and 

 Cape Villano, at the south-west corner of the Bay 

 of Biscay, and found it to work perfectly well. 

 Even without the Massey fly, it gives a fairly 

 approximate sounding in as great a depth as 1 50 

 fathoms, when the ship is running at any speed not 

 exceeding five or six knots, a result quite unattain- 

 able by the ordinary deep-sea lead. There is no 

 difficulty whatever in using it with a Massey fly 



1 See papers on "Deep- Sea Sounding" included in present 

 volume ; also 37 below. 



E 2 



