1914] Sumner, et al.: Physical Conditions in San Francisco Bay 59 
ployed by us, is sufficiently precise to meet the needs of our work 
in San Francisco Bay. Indeed, a higher degree of precision would 
searcely have added to the scientific value of the data presented. The 
problems have been quite different from those which are dealt with 
in much of the recent oceanographic work, where it has been important 
to distinguish between neighboring strata or currents which differ 
but slightly in salinity. In San Francisco Bay, on the other hand, 
very great differences of salinity were found in passing from one end 
of the bay to the other, or even on comparing samples taken at different 
times of the year. Any slight errors, due to defective methods, would 
thus be insignificant in comparison with actual differences among the 
water samples tested. 
In the compilation of tables 12 to 18, giving the results of our 
salinity determinations, the same procedure has been adopted as in 
the case of our temperature figures, and the reader is consequently 
referred to pp. 28 and 35 for an understanding of these tables. Our 
discussion of the salinity data will likewise follow much the same 
order as in the case of temperature. 
It must be borne in mind that these tables do not show the highest 
and the lowest individual salinities found by us, since the figures, 
even for single stations and single periods, are averages based upon 
two or more samples. The highest salinity met with in the bay was 
33.27, at station H-5188 (4967), ebb tide, bottom, October 12, 1912. 
The lowest figure was 3.25, at H—-5088 (4975), flood tide, surface, 
April 23, 1912. 
TABLE 12 
SALINITY OF SAN FRANCISCO Bay 
Period I (February 13— February 27, 1912) 
Division 
of Bay Station Surface Bottom Flood Ebb Average* 
3 4967 30.27 31.09 31.09 30.27 30.68 
(36%) 4968 27.90¥ 27.11 28.18 26.84 27.51 
4969 27.44 28.66 28.66 27.44 28.05 
4970 26.96 28.60 28.74 27.71 27.78 
2 4971 26.47 27.73 27.96 26.24 27.10 
(10%) 4972 24.55 26.49 26.39 24.65 25.52 
4973 21.00 24.04 24.55 20.50 22.52 
4974 19.91 23.12 23.42 19.60 21.51 
* Mean of surface and bottom. 
