1914] Sumner, et al.: Physical Conditions in San Francisco Bay 53 
there are two corresponding maxima for air temperature. Since our 
own curve for San Francisco Bay is based upon bimonthly observa- 
tions, it is impossible to state exactly when the maximum temperature 
for the year occurred. Indeed, it is possible that we should ourselves 
have found two maxima if we had obtained records for every month 
of the year. 
“Jon Feb . Apr. May = Jun. Jul Aug. Sept. Oct. Nov. Dec. Jan. 
Fig. J. Comparison of the annual temperature curve for San Francisco 
Bay (already given) and a curve for ocean temperature, which has been ren- 
dered comparable with the former by the omission of those months during which 
no observations were made by the present survey. 
If this diagram for ocean temperatures be rendered comparable 
with ours for the bay by omitting the months for which we have no 
observations, it will be found that only a single maximum is indicated 
(figure J). This, however, falls in October, instead of in July, as 
in the case of our observations. Other differences between these 
curves relate to the time of minimum temperature, and the consid- 
erably smaller annual temperature range shown by the ocean than 
by the bay. 
Curves for water and air temperatures in the Golden Gate (Fort 
Point) based upon ten years’ observations (1874 to 1883) were given 
by Davidson twenty-five years ago (see ‘‘Pacifie Coast Pilot,’’ 4th 
edition, 1889, pp. 228-230). The month of maximum water tempera- 
ture, according to Davidson, is September, the minimum falling in 
January. For the air there are two maxima, one in June, the other 
in September. The mean annual water temperature, based upon his 
figures, is 13°03 C (55°45 F), the annual range being 5°91 ©. For 
our station 4967, nearest to the Golden Gate, the mean annual tempera- 
ture was found to be 12°01 C, the annual range being 4°9 C. 
