CHAPTER 2 

 OBTAINING SEA WATER SAMPLES AND TEMPERATURES 



2-1 GENERAL REMARKS.— Sea water 

 samples are collected from various depths of 

 the ocean by means of specially adapted water 

 sampling bottles. The first bottle was invented 

 by Hooke in 1611. Since then, more than 50 

 types have been developed and used by dif- 

 ferent oceanographic institutions throughout 

 the world. However, the types of bottles in 

 general use have been reduced to a few of simple 

 but rugged design. This is so because only a 

 few are designed to withstand the rigorous 

 working conditions and have specific or desirable 

 features. The type used by the Hydrographic 

 Office is a modification of the one developed 

 by the Norwegian arctic explorer and ocean- 

 ographer, Fridtjof Nansen, in the latter part 

 of the 19th century. This tjrpe is known as 

 the Nansen bottle. 



Temperatures at various depths are obtained 

 with deep-sea reversing thermometers. These 

 special thermometers are attached to the 

 exterior of the Nansen bottle. Reversing 

 thermometers were first developed by the firm 

 of Negretti and Zambra, of London, in 1874. 

 The modern thermometers are precision in- 

 struments which are accurate to 0.01° C. They 

 are calibrated carefully before usage and are 

 recalibrated periodically. 



Other temperature-measuring devices and 

 sea water samplers have been developed in 

 recent years. A few such instruments are the 

 bathythermograph, the Spilhaus-Miller sea 

 sampler, the salinity-temperature-depth re- 

 corder (STD), the conductivity-temperature- 

 indicator recorder (CTI), and the microthermal 

 depth recorder. Compared with the Nansen 

 bottle, all of these instruments are limited to 

 relatively shallow-depth operations. In addi- 

 tion, the temperature measuring elements either 

 do not attain the degree of accuracy and 

 reliability of the reversing thermometer or are 

 still in the experimental stage. 



The bathythermograph is an instrument used 

 extensively for obtaining temperature versus 

 depth observations. Its operation is explained 

 in this chapter. Additional instructions for 

 survey operations are given in chapter 14. 

 Explanation and instructions for operating the 

 Spilhaus-Miller sea sampler are given in this 

 chapter. 



2-2 INSTRUCTIONS FOR OPERATING 

 THE NANSEN BOTTLE.— The Nansen bottle 

 is a metal reversing water sampler with a 1.25- 

 liter capacity. Its purpose is to bring an 

 uncontaminated water sample from a desired 

 depth to the surface. It is fitted with a 

 tapered plug valve at either end and is lowered 

 on the oceanographic wire in the open position, 

 thus flushing itself during the lowering. When 

 the bottle reaches any predetermined depth, a 

 brass messenger is dropped from the deck. 

 The messenger serves to disconnect the top of 

 the bottle from the wire; the bottle then re- 

 verses, making a 180° arc with the wire. The 

 plug valves close when reversal occurs, en- 

 trapping a water sample from the desired depth, 

 and a second messenger is released which in 

 turn effects the reversal of a lower bottle, and 

 so on (fig. 2-1). 



To keep contamination of water samples to 

 a minimum, Nansen bottles are constructed of 

 brass. To provide resistance to action of salt 

 water the exterior parts are chromium plated 

 and the interior is silver or tin plated. The 

 exterior is painted yellow to increase visibility 

 in the water. Should a Nansen bottle be in- 

 advertently lowered with the plug valves 

 closed, the pressures encountered will crush it. 



Each Nansen bottle is fitted with a frame to 

 hold deep-sea reversing thermometers. Most 

 frames hold 2 thermometers, although frames 

 for 3 thermometers are sometimes used. Brass 

 tubes in the frame, into which the ther- 

 mometers are inserted, are slotted to permit 

 easy reading of the scale. One end of each tube 



H. O. 607 



