Chapter Two 



METHODS OF OBSERVATION 



The obstacles encountered by the collector of hydrographic data pertaining 

 to the Gulf Stream are numerous and formidable. Although many diffi- 

 culties remain, modern technology has been of great assistance in oceano- 

 graphic research. 



INSTRUMENTS USED IN GULF STREAM WORK 



The instruments utilized are not, for the most part, produced exclusively 

 for the study of the Gulf Stream. The reversing bottle, the thermometer, 

 and the bathythermograph are employed in every ocean area. However, 

 the use of these instruments in the Gulf Stream does require special 

 techniques. For example, anchor stations are out of the question in the 

 strongest part of the Stream, and hydrographic stations are usually made 

 by steaming against the surface current to reduce the wire angle in the low- 

 speed water below. Because most readers are not hkely to be familiar 

 with these instruments, this chapter offers a brief description of them and 

 of the techniques for their use at sea. 



Reversing bottle. — The reversing bottle is made of metal and is fitted 

 with a valve at each end. When lowered to the desired depth it is 

 tripped by a messenger (a weight which slides along the wire). As it 

 turns over, the valves close and a little more than 1 liter of water is 

 sampled. Normally a number of bottles are lowered in series on the 

 same cable. 



Salinity is determined by chemical titration, usually on shore. The 

 standard of accuracy is about +0-02%(, (%(, means parts per thousand). 



