109 
By consulting the table, it will be seen that the state of the 
tide has but little influence upon the density, though the 
depth of the water has and the prevalence of strong winds 
may increase or diminish it. There is shown a gradual and 
constant increase of density as the southern portion of the 
Sound, where it opens upon the Chesapeake, is approached. 
There is also an increase of density when in the vicinity of 
the openings into the Bay and a decrease in the various rivers 
and off their mouths. 
Though the density of the water increases, yet the differ- 
ence between the maximum and minimum densities steadily 
decreases to the southward, showing that the oysters on the 
northern beds are exposed to greater fluctuations of density, 
and probably salinity, than those on the beds to the south- 
ward. 
There were no heavy rains during my stay in the Sounds 
and the densities given therefore show only the condition of 
the water in that respect during dry weather. I w T as informed 
that there was a noticeable change in its character about the 
mouths of the 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 densi- 
ties of the Sound amounts to 0.0053 ; but the difference be- 
tween the maximum and minimum densities 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 takes 
place over the Shark’s-Fin and Fishing Bay beds and the least 
difference over any of the main beds is that on the Little 
Thoroughfare, wdiich amounts to 0.0009. 
It would be perhaps still more correct to divide the Sound 
into several parts and consider the fluctuation of densities 
over them thereby assembling a larger number of observations. 
Throwing out the Fishiug Bay beds, which by their po- 
sition are removed to a great extent from the conditions af- 
fecting the other beds and including all those south of Clay 
Island as far as Piney Island Bar, when the influence of the 
Manokin and Annemessex Pi vers would be felt, the difference 
of density amounts to 0.0028. 
