ton Ewing piston corer, were lowered by the 

 anchoring winch to this depth, some 5 hours 

 would be required to lower and raise it for a 

 single core. 



Many observations can be taken simultane- 

 ously. Thus, bathythermograph lowerings, 

 vertical plankton tows, subsurface visibility 

 measurements, and associated meteorological 

 observations can be taken while other lowerings 

 are in progress without adding to the time on 

 station. 



Tlie efficiency with wliich tlie observations and 

 measurements are obtained during the time the 

 sliip is occupying tlie oceanographic station 

 naturally depends upon the number of personnel 

 available and the degree of training they have 

 had. On U.S. Navy survey ships, there may be 

 three to 12 men assisting the oceanographers, 

 depending upon the requirements for a partic- 

 ular station. For example, several men are re- 

 quired to rig and put the Ewing piston corer 

 over the side, and three men are required to 



make Nansen bottle casts (a winch operator, a 

 bottle passer, and a bottle hanger). 



After the last piece of equipment is back 

 aboard, the ship gets underway for the next 

 station, which may be a few miles or possibly a 

 hundred miles away. While the ship is steam- 

 ing to the next station, water samples taken on 

 the previous station are analyzed and recorded 

 on log sheets, the samples to be returned to 

 laboratories are properly labeled and stowed, 

 and equipment and instruments are cleaned and 

 prepared for the next station. Meanwhile, un- 

 derway measurements and observations may be 

 taken. In the drafting room or scientific office 

 and in tlie laboratories, the data recently col- 

 lected are processed and analyzed. 



In the following chapters of this instruction 

 manual for obtaining oceanographic data, the 

 instruments, observation techniques, sample 

 analysis techniques, and data processing meth- 

 ods used at tlie U.S. Naval Oceanographic Office 

 are described in further detail. 



A-7 



