THE SCOTTISH MARINE STATION AND ITS WOEK. 229 



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Fig. 7.— Dr. H. R. Mills' Water-bottle. A A, central tube ; b, base- 

 plate; c, india-rubber ring, to form a water-tight joint with the lower 

 edge, F F, when the bottle is shut ; D, stop-cock for emptying the bottle ; 

 E, stop-cock for admitting air ; F F, edge of cylinder; G, thin plates of 

 metal (three in number) forming guides to the cylinder; H, india- 

 rubber saucer in which i rests when the bottle is closed ; I r, knife 

 -edged flange ; j j, tube to protect lock ; K, flanged gallery on top of 

 cylinder; l l, springs sustaining cylinder; M, tube for withdrawing 

 L L from K ; N, india-rubber buffer ; o, spring catches for locking 

 cylinder when closed, 



