Figure 



Nansen bottles in racks. 



in the racks in the order in which they are going 

 to be used on the station. Deep-sea reversing 

 thermometers are placed in the thermometer 

 frames as described in section 2-22 and the 

 saUnity, oxygen, and other sample bottles are 

 placed in the racks below the Nansen bottles. 

 The Nansen bottle, thermometer, and sample 

 bottle numbers are recorded on oceanographic 

 log sheet A, as shown in chapter 14. 



2-10 Bottles in Series. — To expedite work 

 at sea, Nansen bottles are used in series; 

 several bottles are attached at intervals along 

 the wire during a single lowering, or cast. 

 Nearly simultaneous water samples and tem- 

 peratures at different depths are obtained with 

 one lowering. Up to 12 bottles may be used 

 on one cast. It is not considered safe to place 

 more than 12 bottles on ^^j-inch wire. The 

 depths to which they will be lowered is deter- 



mined prior to starting a cast. Generally, the 

 bottles are spaced at close intervals near the 

 surface since there are greater changes of tem- 

 perature, salinity, oxygen, and other variables 

 in this region. At lower depths, the bottles 

 usually are spaced at greater intervals because 

 the temperature and salinity values generally 

 change more slowly with increasing depth. 

 Thus, with 12 to 15 bottles on the wire, the 

 first cast may reach from the surface to only 

 300 or 400 meters in depth. A second or even 

 third cast commencing at the greatest depth of 

 the previous one is usually necessary to get 

 adequate samples to all desired depths. 



2-11 The Standard Depths.— The Inter- 

 national Association of Physical Oceanography, 

 in 1936, proposed the following standard depths 

 at which observations should either be taken 

 directly or the data adjusted by interpolation 



10 



H. O. 607 



