354 POPULAR LECTURES AND ADDRESSES. 



a length of 3,000 fathoms (about 43 Ibs.) coiled 

 on the wheel. When we do not get bottom 

 with 3,000 fathoms, the process of splicing on a 

 new length of wire ready coiled on a second 

 wheel, is done in a very short time two 

 minutes at most. The friction brake which 

 you see is simpler in construction than that 

 shown to the Institution of Engineers in 

 Scotland last session, and sent out a year 

 ago to the American Navy Department The 

 brake on the sounding machine now before 

 you is a return to the simple form of brake 

 which I used in June, 1872, when I first 

 made a deep-sea sounding with pianoforte wire 

 in the Bay of Biscay, in 2,700 fathoms. 



A measured resistance is applied systema- 

 tically to the wheel, always more than enough 

 to balance the weight of the wire out. The 

 only failures in deep-sea soundings with 

 pianoforte wire hitherto made have been 

 owing to neglect of this essential condition. 

 The rule I have adopted in practice is to 

 apply resistance always exceeding by 10 Ibs. 



