64 



THE VOYAGE OF H.M.S. CHALLENGER. 



iron, and a whip rove through it to trice up the set of accumulators B. At the bottom 

 of the accumulators a 9-inch gin-block C was hooked with the sounding line rove through 

 it and secured to the sounding rod and sinkers D. To the line immediately above the 

 sounding apparatus was attached a water bottle E, and above the water bottle two, or 

 sometimes three, thermometers (these instruments will be described subsequently), and a 

 pressure gauge F. The whole apparatus ready for sounding is shown in the figure, but it 



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 JDetftEwiine 



•Fig. 16.— Diagram to illustrate the method of Sounding 



must be explained that, owing to the constant motion of the ship, the sounding rod and 

 sinkers were lowered into the water directly they were lifted over the side to prevent their 

 swaying backwards and forwards with the risk of doing considerable damage, and the water 

 bottle and other instruments were attached after the sinkers were in the water. Before 

 the sounding line was bent on to the rod it was rove through a thimble at the end of a 

 lizard, so that the bight of the line could at any time be hauled in close to the dredging 

 platform. 



