8o8 OYSTERS, AND ALL ABOUT THEM. 



tributaries of the Sounds, after a heavy rain-fall, and the 

 effect upon the oysters was also perceivable. 



The difference between the maximum and minimum 

 density of the Sound amounts to 0.0053 '> but the difference 

 between the maximum and minimum density on each bed 

 will give a more correct idea of the changes to which the 

 oysters are exposed. The greatest difference is 0.0025, 

 which occurs on the Shark's Fin and Fishing Bay Beds, 

 and the least difference on any of the main beds is 0.0009 

 on the Little Thoroughfare. 



. . . . If the change of density over these beds 

 (as shown by these tables) represents with approximate 

 accuracy the change of salinity of the water, the fluctuation 

 is too slight to seriously affect the beds or oysters ; but if 

 the slightness of the change is due to organic matter held 

 in solution by the waters of the ebb tide, which would 

 replace the salt of the flood, there may be a much greater 

 difference in the salinity of the flood and ebb than has been 

 indicated by the hydrometer. 



CURRENTS. 



In reviewing the statements regarding the currents, 

 Lieutenant Winslow says " that the strongest on both tides 

 were those over Terrapin Sands during the spring tides, 

 their velocity being about one mile per hour." As the 

 observations over the Sound were made during various 

 states of the weather and of tide, the highest velocity 

 obtained is probably as great as ever sets over any of the 

 beds. 



The velocity, except within wide limits, however, is 

 not so important to the oysters as the direction of the 

 current. 



