The instruments and procedures employed at sea are those more or less 

 standard in oceanography and will be described simultaneously with a 

 description of a hydrographic station. Such stations take 1^ to 4 hours, 

 averaging about 2 hours o Upon arrival on station, the vessel is hove to 

 and the 900 ft„ bathythermogi'aph lowered and retrieved Hansen type water 

 sampling bottles carrying protected and unprotected reversing thermometers 

 are then lowered on the "hydrographic cast". After ten minutes of "soaking" 

 the thermometers are considered to be at equilibrium, the water bottles are 

 reversed by messengers along the wire, and then retrieved, A surface water 

 sample is collected in an open bucket, A second "on station" bathythermograph 

 observation is accomplished immediately after the "cast" is retrieved and 

 this is followed by the plankton tow. Water samples for the determination 

 of oxygen, inorganic ]^osphate and salinity are drawn in the order mentioned 

 and all thermometers read and then check read by a second observer. 



Oxygen content is determined by the Winkler titration method. In- 

 experienced personnel run duplicate titrations but it has been found that 

 a single titration by experienced observers is sufficient. 



Inorganic phosphate is determined through use of the Automatic Servo- 

 Operated Photometer, an instrument developed by the Scripps Institution of 

 Oceanography o A pair of determinations are made for each water sample. 



Salinity samples, stored in citrate bottles, are returned to the PcO.F,I. 

 laboratory in Honolulu, Two or more chlorinity determinations of each sample 

 are made by the Knudsen method and converted to salinity. 



Most of the methods employed in processing the data are those used on 

 the Marine Life Research Program of the Scripps Institution of Oceanography, 



The readings of protected and unprotected thermometers are "corrected" 

 to readings "in situ" through the use of graphs,, 



Thermometric depths are computed and plotted on a graph of wire length 

 minus thermometric depth versus wire length as developed by Robert 0, Reid 

 and described by La Fond (1950) , The actual depths of the water sampling 

 bottles are determined on the basis of this curve and therefore the actual 

 depths of all measurements of the physical and chemical properties are known. 

 These measurements of temperature, salinity, oxygen and inorganic phosphate 

 are plotted against depth for each hydrographic station. The points are 

 then joined by smooth curves. The curve drawing involves, of course, an 

 interpolation between points but a sufficient number of sampling bottles 

 are included in each hydrographic cast that the interpolation error is quite 

 small o In the case of temperature, the interpolation in the upper 275 meters 

 is aided by the continuous bathythermograph trace. From the vertical distri- 

 bution curves the interpolated values are read at standard depths and tabu- 

 lated, <f tj, a quantity approximately equivalent to the density, is determined 

 through the use of the tables of La Fond (19^0), From the values of temperature 

 and salinity at standard depths djmamic computations are performed, using graphs 

 printed by the U.So Navy Hydrographic Office, except that the second order terms 

 of the specific voltime anomaly involving pressure are computed using a slide 

 rule. The results of these computations lead to the determination of the ocean 

 currents which are associated with the distribution of mass. 



