12 



University of California Publications in Zoology [Vol. 15 



see Kofoid. 1911b). It can be used only on the large cable. When 

 lowered to the desired depth the bottle is closed by means of a mes- 

 senger, after which it is raised on deck and the temperature is taken 



(see p. 11). Except during July. 

 1912, this method of obtaining 

 water samples for plankton work 

 has been seldom u.sed since July 16, 

 1910, at which time the Ekman 

 bottles were first put into e(immis- 

 sion. 



(/') The Elcman reversing water 

 bottles. — These bottles are so con- 

 structed (see Ekman, 1905a) that 

 several of them may be clamped 

 to the same cable and a series of 

 depths explored at the same time. 

 After they are lowered to the de- 

 sired depths, the bottles are allowed 

 to remain open for from two to 

 three minutes to insure the setting 

 of the thermometers (see p. 16). 

 A messenger is then sent, which de- 

 scending at the rate of two and 

 one-half meters per second, reverses 

 and closes the uppermo.st bottle, 

 thereby freeing a second messenger 

 which reverses the second bottle, and 

 so on. After all have been closed, 

 which can usually be detected by 

 feeling the cable, the cable is raised 

 until the uppermost bottle reaches 

 the deck. This is then detached 

 and handed over to the hydro- 

 grapher, who notes the temperature 

 and places the bottle in a specially 

 made rack which allows the water 

 to run out into a container (see 

 p. 17). By this means, as soon as 

 the water has been removed from 

 the terminal bottle, everything is in 



Pig. 1. A combination apparatus: 

 Kofoid closing net, Ekman water bot 

 ties, and Ekman current meter. 



