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BULLETIN OF THE BUREAU OF FISHERIES 
22.36; October, 21.99; and December, 22.78. Area H, January, 16.85; March, 
16.22; May, 11.95; July, 15.57; August, 16.45; October, 16.74; and December, 
18.25. Area X, January, 13.57; March, 13.77; May, 5.81; July, 9.40; August, 
10.65; October, 13.70; and December, 12.42. 
During the year 1922 only 2 cruises were made, 1 in January and 1 in March; 
and a distinctly lower salinity was found during the latter cruise. At area A, near 
the mouth of the bay, the salinities at 30 meters for January and March were 25.89 
and 25.10, and for area L, near the mouth of the Potomac River, 20.41 and 17.12. A 
similar condition was found at the surface and at 20 meters. 
Averages of the surface salinities of 12 widely distributed areas ( G , F, D, C, B, A, 
H, J, I, M, X, Z ) during the cruises of 1916 show the seasonal condition mentioned 
above: January, 18.26; March, 17.88; April, 13.70; June, 15.85; and July, 16.88. 
Surface salinities for the September cruise were markedly higher than those of the 
summer and spring cruises, but, owing to the fact that the data for areas G and D are 
lacking, no average is given for that cruise. Also the data at each area for each cruise 
show a similar relation: Area A, January, 22.74; March, 20.14; April, 18.46; June, 
22.11; July, 22.54; and September, 23.59. Area Ii, January, 18.53; March, 17.30; 
April, 13.21; June, 14.33; July, 15.99; and September, 16.31. And area AT, January 
11.13; March, 12.92; April, 5.88; June, 8.30; July, 5.41; and September, 11.09. 
The data show that there was a minimum degree of salinity in Chesapeake Bay 
during those cruises taken in the spring months of 1916 and 1920, and that, in general, 
higher salinities occurred during the summer, fall, and winter cruises. Also in 1922 
the data show that salinities of the March cruise were distinctly lower than those of 
the January cruise, but in the winter and spring of 1921 this relation was disturbed in 
the lower part of the bay. It has been pointed out that the winter months, December, 
1920, and January and February, 1921, were unusually mild in Maryland and that 
probably that accounts for the low salinities during that time. 
A study, then, of the salinities of the various cruises taken on Chesapeake Bay 
favors the view that a decided decrease in salinity occurs during the early part of the 
year and that later in the 3 7 ear there is a tendency for it to increase again. Such a 
view is in keeping with the time of occurrence of the maximum discharge of the water 
from the large rivers entering the bay, and, as we shall see in the next section, with 
the tendency for the more saline deep water of partly marine origin to make its way 
up into the bay during the latter part of the year. 
RELATION OF DIRECTION AND VELOCITY OF CURRENT AT 24-HOUR STATIONS 
TO SEASONAL SALINITY 
It is evident that the degree of salinity depends on (1) the amount of fresh water 
brought in by rivers or b}^ local precipitation, (2) on the amount of saline water brought 
in by the sea combined with (3) the mixing of these waters, and (4) the amount of 
evaporation of the water. The records of the water-supply department of the United 
States Geological Survey show that the maximum discharges of such large rivers as 
the Potomac and Susquehanna at points somewhat above their entrance into the 
Chesapeake occur during the spring months, March, April, or May, and that the 
min imum discharges are in August, September, or October. These conditions alone 
would tend to establish a low salinity in the bay during the spring and a higher one 
during the summer, fall, and winter. 
On the other hand, Chesapeake Bay is a tidal estuary, although the tidal currents 
are weak compared to those of many other estuaries. A clearly defined ebb and flood 
