340 CALIFORNIA ACADEMY OF SCIENCES. 



records of temperature are necessarily imperfect, but as 

 they represent mostly the mean temperatures, taken from 

 four to live observations on the surface, and from more than 

 one in great depth, they really are entitled to great consid- 

 eration, although the apparent smallness of their number 

 may ]iot seem to warrant it. 



Furthermore, the temperatures registered on Maury's 

 charts coincide remarkably with Belknap's figures. 



We know the law of the evenness of the ocean tempera- 

 ture. In the open sea the temperature of the surface 

 water shows a daily range of hardly more than one de- 

 gree of Fahrenheit, and nearest the coast sometimes of two 

 or three degrees. The yearly variation will amount only 

 rarely to ten degrees in our latitude. The surface water at 

 the Golden Gate, for instance, shows between the years of 

 1874 and 1883 a lowest mean temperature of 50^.49 in Jan- 

 uary, and a highest mean temperature of 59^.68 in Septem- 

 ber, according to the "Coast Pilot," by Prof. G. Davidson. 



In compiling the temperatures derived from the above- 

 named sources, we cannot make therefore a great deviation 

 from truth. 



It is proper to mention the fact, that Belknap's tempera- 

 tures have furnished the foundation for the most recent de- 

 scriptions of the North Pacific ocean currents. I refer 

 especially to the work on " Oceanography," by F. Attlmayr, 

 published under the auspices of the Secretary of the Aus- 

 trian Navy in 1883. Yet no attempt has been made to adapt 

 the figures of the Tascarora to the details of the currents 

 along the coast. 



. Therefore it has been my endeavor to utilize every relia- 

 ble record of temperature from Belknap's Soundings, as well 

 as from every other trustworthy source, and to determine b}'" 

 them the facts from which I could illustrate the direction 

 and the extent of the ocean currents along the coast of 

 California. 



As the figures recorded by Belknap harmonized as afore- 



