CHAPTER V 



WATERS OF THE OCEAN : COMPRESSIBILITY, 

 PRESSURE, COLOUR, VISCOSITY, PENETRA- 

 TION OF LIGHT, TIDES, WAVES, SEICHES 



In the preceding chapters we have dealt 

 with the salinity and temperature conditions 

 in the ocean, and it is now desirable to say a 

 few words about some of the other physical 

 characteristics and movements of ocean 

 water which must be taken into consideration 

 in the discussion of oceanic circulation and of 

 marine biological problems. 



Compressibility of Water. — In 1661 some aca- 

 demicians at Florence, wishing to test the 

 compressibility of water, filled a thin gold 

 globe with that liquid, and, after hermetically 

 sealing it, exposed it to pressure with the 

 view of altering its form, well knowing that 

 any alteration in form of a sphere must be 

 accompanied by a diminution in volume. 

 The consequence was that the water forced 

 its way through the pores of the gold and 

 stood on the outside of the globe like dew. 

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