1914] Sumner, et al.: Physical Conditions in San Francisco Bay 99 
Golden Gate, to 13°81 C, which is that for a station in the southern 
arm of the bay. The highest single temperature encountered by us 
was 20°6 C, on July 23, 1913, in shoal water in the lower part of the 
bay. The lowest was 6°0 C, on January 13, 1913, in Carquinez Strait. 
The seasonal means varied from 8°33 C, representing the mean 
temperature of the entire bay in January, 1913, to 16°68 C, repre- 
senting the mean for the bay in July, 1912. The annual range of tem- 
perature for the bay as a whole was thus 8°35 C. The greatest sea- 
sonal range was met with at the two ends of the bay, particularly the 
northern, the least range being found in the vicinity of the Golden 
Gate. The regional range was lowest in February, when the highest 
and lowest temperatures recorded differed by 0°8 C. It was greatest 
in July, when the range was about 5° C. 
9. Comparisons have been offered between the annual mean and 
the annual range of water temperature in San Francisco Bay with 
corresponding figures for two inlets of the ocean, on the opposite side 
of the continent. Chesapeake Bay (or the lower third of it, from 
which most of the records came), has about the same latitude as San 
Francisco Bay, while Woods Hole harbor is considerably farther 
north. The figures are as follows: 
Mean Range 
San Prancisco! Bayi -..-2-2...--.--- 12°91 € 8235 C 
@hesapealken aye sss. eee ee eee 14°38 C 22°12 € 
Woods Hole harbor ..............-..... 10°56 C 21250 C 
10. For the Pacific Ocean in the neighborhood of San Francisco, 
the figures, according to Thorade (1909), are: mean, 12°86 C; range 
323. Thus, it is plain that the more equable climate of the Pacific 
coast of the United States, as compared with that of the Atlantic coast, 
is associated with a much greater uniformity in the temperature of 
the neighboring water masses. 
11. During five of the six bimonthly periods of observation, the 
surface temperatures, throughout San Francisco Bay, were higher 
than those for the bottom. In January, however, this condition was 
reversed, the surface temperatures being lower than the bottom ones, 
by an average difference of 0°2 C. 
12. The mean salinity of the entire bay, during the year of our 
observations, was 27.48 per mille. This is a grade of concentration 
such as would result from a mixture of 81 per cent of ocean water 
and 19 per cent of river water. The regional means ranged from 
