6 



f 



Figure D-S. Nansen bottle with reversing ther- 

 mometers. 



D-3). Frames for two, three, or four themioin- 

 eters are used. The tubes of the frame are slotted 

 and perforated so thermometers can be read 

 without remo^'ing tliem from the tubes and to 

 permit water circulation so the thermometei-s 

 will come to temperature more rapidly. The 

 tubes contain coil springs and rubber pads to 

 hold the thennometers securely in place and to 

 provide protection against shock. When a Nan- 

 sen bottle is reversed at a given depth, the ther- 

 mometer frame is inverted. 



D-9 Nansen Bottle Racks. — An arrange- 

 ment for racking the Nansen bottles is essential 

 for proper conduct of operations. The Nan.sen 

 bottle rack should be fabricated to liolcl 12 or 

 more bottles side by side. It must be constructed 

 so that the Nansen bottles are held securely in 

 a vertical position and yet can be removed 



D-4 



AFTER TRIPPING 



Figure D-4. Nansen bottle in three positions — before 

 tripping, during tripping, and after tripping. 



readily. Immediately below each Nansen bottle 

 the rack should have compartments to hold sev- 

 eral water sample bottles. The rack should be 

 moimted on a bulkhead near the platform and 

 A-Frame in a location protected from the sun 

 and weather. It should be at a height for easy 

 reading of the reversing thennometers (fig. 

 D-5). 



D-10 Standard Depths.— In 1936, the Inter- 

 national Association of Physical Oceanography 

 proposed the following standard depths at 

 which observations should either be taken di- 

 rectly or the data adjusted by interpolation 

 from the distribution at otlier levels. These 

 standard depths, in meters below the sea sur- 

 face are : 0, 10, 20, 30, 50, 75, 100, 150, 200, (250) , 

 300, 400, 500, 600, (700), 800, 1,000, 1,200, 

 1,500, 2,000, 2,500, 3,000, 4,000, and thence every- 



