4 Vnircrsity of California Publications in Zoology [Vol. 15 



is given, in addition to the tables of data. However, as most of the 

 apparatus used prior to June, 1908. at which time the "Alexander 

 Aofassiz" began active work, has also been employed since that time 

 while many others have been added, the descriptions apply particu- 

 larly to this later period, a brief historical resume serving in general 

 to cover the preceeding years. Furthermore, since most of the ap- 

 paratus has been completely described elsewhere, it is considered in 

 detail only when this is demanded in the interest of clearness, while 

 the methods of collecting, recording, and analyzing are more fully 

 discussed because of their important bearing upon the interpretation 

 of the tables. Finally, since an accurate interpretation depends upon 

 a knowledge of the magnitude of the inevitable errors involved, espe- 

 cially in the determination of position, depth, temperature, and 

 salinity, such errors are fully discussed under the proper headings. 



The actual work at sea has involved the co-operation of many per- 

 sons to whom the institution is deeply indebted. The services of most, 

 however, are so interdependent that it would be nearly if not quite 

 impossible to separate them and duly credit each person with the par- 

 ticular services rendered. But there are a few who have been so 

 definitely connected with the work, and whose intiuenee upon the 

 results achieved has been so great, that they must be mentioned here. 



Except for the services and ingenuity of Professor C. A. Kofoid, 

 who had charge of most of the earlier work and to whose ability in 

 devising mechanical appliances and .skill in working out details some 

 of our most important apparatus is due, much of the work actually 

 accomplished would have been impossible. This is especially true of 

 the period from 1901 to 1906 when, crippled by lack of funds, the 

 work at sea depended entirely upon the improvising of inexpensive 

 apparatus. Professor Kofoid was ably assisted during part of the 

 summer of 1901 by Professor W, J. Raymond of the Physics Depart- 

 ment of the University of California, and later in the summer of 1903 

 by Mr. W. T. Skilling. teacher of physics and physical geography in 

 the State Normal School at San Diego. 



Since 1908 the scientific crew has as a rule consisted of Captain W. 

 C. Crandall, George F. ]McEwen, and Ellis L. Michael, who have been 

 responsible for most of the methods of collection employed from that 

 time to this. It is in fact due to Captain Crandall's exceptional 

 ability in navigating and maneuvering the "Agassiz" that the magni- 

 tude of the inevitable field errors have been reduced to a minimum. 



