29 



tions affecting the other beds, and including all those south of Clay Island as far as Piney Island 

 bar, where the influence fit the Manokin and Annemessex Rivers would be felt, the difference of 

 density amounts to 0.002S. 



The difference of density over the beds south of Little Island and north of Little Annemessex 

 River is 0.0031. 



The difference of the beds south of Jane's Island Light is 0.0020. 



These differences show that the greatest fluctuation is over the beds in the middle of the 

 Sound, and is probably due to the influence of the Big Annemessex and Manokin Rivers and the 

 waters entering by Kedge's Strait. 



Throughout the Sound there is a marked difference between the densities of the water taken 

 about the latter part of August and the first part of September and those taken in October. This 

 difference is given in the following table: 



Bed. 





Flushing Bay Aug. 24 



WerePoint Aug. 24 



Nanticoke Middle Ground Aug. 26 



Bed north of Turtle Egg Island Aug. 26 



Chain Shoal Aug. 27 



Piney Island Bar , . . . Aug. 28 



Manokin Bed -v Aug. 27 



1= - 





' 



3 S 







o 2 







o '^3 





£ >> 1 









<e > 





3 '55 



u 

 eg 



r° 





Differe 

 den 



Oct, 



5. 



.0018 



Oct, 



5 



.0014 



Oct. 



5 



.0014 



Oct. 



4 



.0016 



Oct, 



8 



.0011 



Oct. 



4 



.0010 



Sept. 



30 



.0017 



i 



Harris's Bock I Aug. 29 



Great Bock - : Aug. 30 



Woman's Marsh I Aug. 30 



Great Thoroughfare | Sept. 5 



California Sept. 6 



Oct. 1 

 Sept, 28 

 Sept. 23 

 Sept. 28 

 Sept, 26 



Johnson's Bock. 



Sept. 6 Sept, 20 





. 0005 

 .0007 

 .0008 

 .0007 

 .0009 

 .0010 



The earlier observations show the least density. 



It will be seen by the table that the observations were made at from two weeks to six weeks 

 apart; that, generally speaking, the amount of difference in the densities increases with the inter- 

 val between the observations, and that the northern beds and those in the rivers are exposed to 

 greater fluctuations of density than the neighboring ones in the Sound. If the change of density 

 over the 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. 



The general set of the currents in the Sound is north and south, following the main channel 

 and diverging slightly about the mouths of the tributaries and straits. 



In the following statements regarding the currents the influence of the wind has not been 

 eliminated, and accounts for many irregularities, both of velocity and direction, and about slack- 

 water, especially of the windward tides, this influence was most apparent. 



In Fishing Bay the currents follow the general bend of the shores and channel, setting over 

 the lower portion, on the flood, to the northward; over the middle portion to the northward and 

 westward, as far as Fishing Point, and above that point and over the upper part of the bay, set- 

 ting to the northward and eastward. The maximum observed velocity of the flood current was 

 0.38 of a mile per hour. The ebb in each portion of the bay sets in an opposite direction to the 

 flood. 



The currents about the northern part of the Were Point bed were measured during and after 

 strong northeast winds, which accounts for the set to the southward and westward, and also for 

 the slight velocity of the ebb, which was only 0.15 of a mile per hour, the northeast wind haviug 

 lasted for two days and having driven a good deal of the water out of Fishing Bay. 



Over the Shark's Fin the flood current sets to the northward and the ebb to the southward 

 and eastward, most of the latter apparently coming from Hooper's Straits. Its maximum velocity 



