from the surface to as near bottom as was practicable. At the 10 

 stations forming the southern end of section W on the third survey 

 the observations extended to 3,000 meters. At the remaining 

 stations the observations were limited to the upper 1,500 meters. 

 The intended depths of observation, in meters, were 0, 25, 50, 75, 

 100, 150, 200, 300, 400, 600, 800, 1,000, and thence by 500-meters 

 intervals, except for the extra southerly extension of section W 

 during the third survey where the depths of observation in the 

 second 1,000 meters were 1,200, 1,400, 1,600 and 2,000 meters. 



Temperatures were measured with protected deep sea reversing 

 thermometers, mostly of Richter & Wiese manufacture but with 

 some manufactured by Negretti & Zambra, G. M. Manufacturing 

 Co. and Kahl Scientific Inst. Corp. Depths of observation are 

 based on unprotected reversing thermometers made by Richter 

 & Wiese and by Kahl. As in other years, a program of intercom- 

 parison of protected thermometers was carried out in the field 

 measurements. The thermometers were used in pairs and one of 

 each pair was shifted periodically so that the same thermometer 

 was eventually paired with a number of other thermometers. 

 From a total of 2,201 intercomparisons, the probable difference 

 between the corrected readings of a pair of protected thermometers 

 was 0.010° C. Of these comparisons, 280 involved thermometers 

 having a range of +3° to +13° with a probable difference of 

 0.006°, 1,268 comparisons were between thermometers of range 

 —2° to +8° and gave a probable difference of 0.009°, and 653 

 comparisons were between thermometers having a range of —2° 

 to +20° or greater and gave a probable difference of 0.013°. 

 As most of the observed temperatures listed in the Table of 

 Oceanographic Data are the means of the corrected readings of 

 a pair of thermometers and since many of the thermometers used 

 had recent laboratory comparisons with thermometers tested by 

 the National Bureau of Standards, it is considered that the tabu- 

 lated observed temperatures are good to 0.01°C. 



Salinities were measured with a Wenner salinity bridge. During 

 the winter of 1957-58 an examination of a section extending east- 

 ward from the Grand Banks at about latitude 45° N., occupied 

 by Discovery II on 16-18 April 1957 indicated a probable dis- 

 crepancy of about 0.04% between salinities as determined by 

 Discovery II and as determined on the Evergreen during a survey 

 of the area which included a nearby section occupied 12-13 

 April 1957. It was learned that Discovery's salinities were in 

 essential agreement with those determined by the Woods Hole 

 Oceanographic Institution. A series of check measurements was 

 therefore made to determine if the calibration curve for the Coast 

 Guard's Wenner bridge were in error. 



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