OYSTER CULTURE IN AMERICA. 835 



Lieutenant Winslow speaks at great length on the 

 specific gravity of Parriplico Sound, situate on the coast of 

 Carolina, south of Chesapeake Bay, in North America. 

 He describes it as an enormous sheet of land-locked water, 

 comprising with its tributaries an area of 1,149,400 acres. 

 The general depth of the water is from fifteen to twenty 

 feet. In the deep water the bottom is soft, but in the 

 neighbourhood of the shoals and shores it becomes harder, 

 consisting of sticky mud or sand. There are no rocks 

 other than " oyster rocks," in this or any of the other 

 Sounds. There are two small openings into it from the 

 sea, giving just sufficient amount of sea-water to temper 

 the extreme freshness that would otherwise prevent the 

 growth of shell-fish. 



It occasionally happens that in the extreme north part 

 of the Sound, after heavy freshets, the water will become 

 too fresh, and oysters will either perish or become greatly 

 impaired in quality ; the average density of the water is 

 1.0115, which, however, varies greatly with the locality, 

 weather, and season of the year. The usual practice was 

 to obtain and test a specimen of water every two and four 

 hours when under way, and every four hours when at 

 anchor. The current was measured whenever an anchorage 

 specimen was taken. There were 2500 specimens of water 

 tested in this locality. 



Considerable variations were found in density in every 

 locality, and in many the range was abnormally large. 

 These variations did not appear to be altogether influenced 

 by the wind prevailing at the time, and both high and low 

 specific gravities were found in the same locality, with the 

 wind in nearly the same direction and of nearly the same 



force. Neither did the current appear to have the influ- 



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