378 POPULAR LECTURES AND ADDRESSES. 



under the full speed of a modern fast steamer. It 

 may indeed be said to be a practical impossibility to 

 take a sounding in 20 fathoms from a ship running 

 at 1 6 knots, with the best and best-managed ordin- 

 ary deep-sea lead. Taking advantage of the great 

 strength, and the small and smooth area for re- 

 sistance to motion through the water, presented by 

 pianoforte wire, I have succeeded in overcoming 

 all these difficulties ; and with such a sounding 

 machine as that before you the White Star liner 

 Britannic (Messrs. Ismay, Imrie, and Co., Liver- 

 pool), now takes soundings regularly, running at 16 

 knots over the Banks of Newfoundland and in the 

 English and Irish Channels in depths sometimes as 

 much as 130 fathoms. In this ship, perhaps the 

 fastest ocean-going steamer in existence, the 

 sounding machine was carefully tried for several 

 voyages in the hands of Captain Thompson, who 

 succeeded perfectly in using it to advantage ; and 

 under him it was finally introduced into the service 

 of the White Star Line. 



The steel wire which I use weighs nearly \\ Ibs. 

 per 100 fathoms, and bears when fresh from 230 to 

 240 Ibs. without breaking ; its circumference is only 

 "03 of an inch. By carefully keeping it always, 

 when out of use, under lime water 1 in the galvanized 

 iron tank prepared for the purpose, which you see 

 before you, it is preserved quite free from rust, and, 



1 The use in the newest machines of galvanized steel wire renders 

 this precaution unnecessary. 



