352 POPULAR LECTURES AND ADDRESSES. 



nearly as possible up and down, until the whole 

 length out does not exceed a few hundred fathoms. 



[Sir William Thomson next proceeded to 

 explain in detail and to exhibit in action a 

 new sounding machine which had been made 

 according to his designs by Mr. White of Glas- 

 gow for Messrs. Siemens, to be used on board 

 their cable ship Faraday, and which, through 

 their kindness, was exhibited before the Society.] 1 



The wire is coiled on a large wheel (of 

 very thin sheet iron galvanised), which is 

 made as light as possible, so that when the 

 weight reaches the bottom the inertia of the 

 wheel may not shoot the wire out so far as 

 to let it coil on the bottom. The avoidance 

 of such coiling of the wire on the bottom is 

 the chief condition requisite to provide against 

 the possibility of kinks ; and for this reason 

 a short piece of hemp line, about five fathoms 

 in length, is interposed between the wire and 



1 The accompanying drawing (Fig. 44) shows the whole appara- 

 tus with the sounding wheel in its inboard position for hauling in 

 the wire. Detailed drawings are published in the Proceedings of 

 the Philosophical Society of Glasgow for Session 1873-4. 



