Figure D- 



Xaiist'ii bottle rack. 



1,000-meter interval to the bottom. The depths 

 in parentheses are optional. All data obtained 

 by Nansen bottles and used at the Oceano- 

 graphic Office are interpolated to standard 

 depths. 



D-11 Nansen Bottles in Series. — To expedite 

 work at sea, Nansen bottles are used in series; 

 several bottles are attached at interrals along 

 tlie wire during a single lowering or cast. In 

 tliis way, nearly simultaneous water samples 

 and temperatures at different deptlis are ob- 

 tained with one lowering. As many as 18 bottles 

 may be used on one cast, depending on the size 

 of tlie wire and the depth of the lowering. The 

 depth to which bottles will be lowered is de- 

 termined prior to starting a cast. Generally, the 

 bottles are spaced at close inten'als near tlie 

 surface since the temperature and cliemical 

 properties are often more variable in this re- 

 gion. One or more casts may be required to sam- 

 ple the water column. This operation is de- 

 scribed by the term "Taking an oceanographic 

 station." 



D-12 Preparing the Nansen Bottles for Op- 

 eration. — Before a Nansen bottle is used on a 

 station, check it carefully for proper operation 

 of parts. Lubricate the valves with a silicone 

 stopcock grease to insure smootli movement and 

 watertight seal. Lubricate all other moving 

 parts with penetrating oil to give free action. 

 Test springs and pins of the messenger- and 

 bottle- releasing mechanisms for proper action. 

 If they are too weak, the bottle may trip pre- 

 maturely or the messenger may release while the 

 bottle is being lowered. If they are too stiff, they 

 will not release, properly "when struck by the 

 messenger. Check the action of tlie air vent 

 screw and tlie condition of the washer. The two 

 air vent holes must not be clogged. The drain 

 petcock valve should tuni smoothly. 



A Nansen bottle spare-parts kit is provided 

 those ships which maintain Nansen bottles for 

 a period of time over several cniises. The kit 

 contains spare clamps, springs, washers, pins. 



and the necessary tools to effect minor repairs 

 and general maintenance. After the bottles have 

 been checked and are in good operating condi- 

 tion, place them in the Nansen bottle rack with 

 the air vent screw at tlie toji. 



When the thermometers for the bottles are 

 selected, place them in a thermometer frame and 

 attach the frame to the bottle. Use two protected 

 thermometers on eacli Nansen bottle. It is cus- 

 tomai-y to place the protected themiometei-s to 

 the left in the thermometer frame and the un- 

 protected to the right. This enables the reading 

 of the thermometers and recording of the data 

 in the proper order for applying the corrections. 

 Thus, errors in computations are reduced. 



It usually is not necessary to have unprotected 

 thermometers on every Nansen bottle used in a 

 cast. They should be placed strategically, how- 

 ever, so "that the depths of reversal of other 

 bottles in the cast can be interpolated readily. 



On shallow casts, i.e., those commencing ^^^th 

 bottles at the surface, it is best to group the un- 

 protected themiometei-s on the lower bottles as 

 this type thennometer will not record accurately 

 at depths less than 200 meters. 



On deep casts, i.e., those commencing with bot- 

 tles at depths below those of the shallo^v cast, 

 it is most important that unprotected thermom- 

 eters be placed on the top and bottom bottles. 

 The remaining unprotected thermometers 

 should be on bottles spaced at as nearly equal 

 distances along the wire as possible. 



After the Nansen bottles have been checked 

 and equipped with thermometers, invert the bot- 

 tles and arrange tliem in the Nansen bottle rack 

 in the order they will be placed on the wire. 



D-13 Spacing the Nansen Bottles. — Several 

 factors influence tlie spacing of Nansen bottles 

 along the wire and these vary from station to 

 station with the types of data sought. While it 

 is desirable to obtain data at or near standard 

 depths, this is accomplished only under condi- 

 tions of zero or near zero wire angles. Such con- 

 ditions are relatively rare at sea. Iso-conditions 

 of temperature and chemical properties may 

 warrant wider spacing of bottles. In order to 

 better delineate gradients of temperature and 

 chemical properties, closer spacing may be re- 

 quired. Often, to determine proper bottle spac- 

 ing on the shallow cast, a bathythermogram is 

 taken and bottles are spaced on the wire in re- 

 lation to the existing thermal conditions. 



D-14 Sea Water Sample Bottles.— The type 

 analysis to be pei-fonned on a sea water sample 

 determines the type sample bottle to be used 

 (fig. D-6). 



1. The sample bottle for salinity determina- 

 tion is the (so called) Citrate of Magnesia bot- 

 tle, 12 oz. (360 ml.), with glass stopper and 

 rubber gasket. 



D-5 



