1914] Sumner, et al.: Physical Conditions in San Francisco Bay 47 
periods). Roughly speaking, we have one season when the bay is 
warmer than the ocean (summer), another when the bay is cooler than 
the ocean (winter), and two seasons when the two are at about equal 
temperatures (spring and fall). That these seasons do not correspond 
with any exactness to the ones generally known by these names is 
obvious. 
Certain supplementary observations, already referred to, were made 
on July 18 to 23, 1913. Some of these afford an interesting basis of 
comparison between the summer conditions of two different years. 
Others were made for the purpose of determining the temperature 
and salinity conditions in the extensive shoal areas which are inac- 
cessible to the ‘‘ Albatross’’. 
Six of the stations of the regular hydrographic series were visited 
at ebb and flood tide. Of these there was one in each of the upper 
sections of the bay, and three in section 4 (see p. 22). In no ease did 
the mean recorded temperature for one of these stations differ from 
that of the corresponding period of the preceding year by as much as 
1° ©. The mean difference was 0°35, the 1913 figures being, on the 
average, higher. 
It was thought that the four regular stations in section 3 might 
not be wholly representative of the conditions throughout that division, 
since they were confined to its northern half. Accordingly, two new 
stations were added, one near the Presidio Shoal, the other in the 
neighborhood of Goat Island. Along with these may be included 
station 5329, near Yellow Bluff (just within the Golden Gate). The 
mean temperature at these three points, at ebb and flood tide, was 
15°12 C. That for this section of the bay during the same month of 
the preceding year was 15°02 C. 
There is thus a pretty close agreement between the results of the 
two years’ observations, in eases where the same or similar localities 
are compared. As regards the shoal water areas, which are not acces- 
sible to the ‘‘ Albatross’’, no comparisons between the two years are 
possible, since we have only the records for July, 1913. It is to be 
noted, however, that the temperatures here found were considerably 
higher than those recorded for the deeper waters of the same sections. 
Thus the temperatures at five launch stations, arranged along a 
line completely across San Pablo Bay, and having a mean depth of 
less than two fathoms, ranged from 17°3 to 20°4 C, the mean being 
18°55 C. In comparison with this, we have 16°52 as the average of 
the twenty figures obtained on the same day (July 21) at station 
