6 



THE EXPLORATION OF THE SEA 



[part I 



latter. The sounding tube itself is comparatively light and the 

 weights (which may be 20 lbs. each) are slung on to the notches in 

 the plunger. It is these weights which carry down the sounding 

 line. Their total mass varies with the depth of water. 



f^'^ 



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Fig. 2. The stop-cock sounding lead of the Prince of Monaco. There are several 

 forms and that figured is described in the Campagne-s Scientifiques, pp. 14 and 15. 

 On the left the sounder is shewn descending, and just touching the bottom. 

 On the right the sounder is shewn ascending. The weights have been released ; 

 the tube is full of the bottom deposits and the stop-cock is closed. 



When the apparatus is to be used one or more weights — cast 

 iron rings — are slipped over the outer tube, and the whole thing 



