was taken on the 27th for Woods Hole, with arrival there on the 

 evening of 30 July to discharge oceanographic equipment. 



At the 186 stations occupied during the surveys in the Grand Banks 

 area and the triangles just north of the Grand Banks, the observa- 

 tions extended to a depth of about 1.500 meters where the depth of 

 water permitted and the dynamic topography was referred to the 

 1,000-decibar surface. At the remaining 67 stations occupied during 

 part two of the postseason cruise, the observations extended from the 

 surface to as near bottom as was practicable and the dynamic topog- 

 raphy was referred to the 1,500-decibar surface. 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-meter intervals. Protected deep-sea 

 reversing thermometers, most of them manufactured by Richter & 

 Wiese, and a few by Negretti & Zambra, and by the G & M Manufac- 

 turing Co., were used to measure the temperatures. Depths of ob- 

 servation were based on measurements made with Richter & AViese 

 unprotected deep-sea reversing thermometers. Intercomparisons were 

 made amongst the thermometers by making periodic shifts in 

 thermometer pairs. Thus most of the thermometers used were each 

 compared with several other thermometers. These intercomparisons 

 helped identify unreliable thermometers. A total of 1,661 individual 

 intercomparisons were made, giving a probable difference between 

 corrected readings of a pair of thermometers of ±0.010° C. As most 

 of the observed temperatures are the means of the corrected readings 

 of a pair of thermometers, it is considered that they are accurate to 

 about ±0.01°. 



As in previous years, water samples were collected with Nansen- 

 type reversing water bottles, transferred to rubber-gasket ed citrate 

 of magnesia bottles, and salinities determined within 24 hours of col- 

 lection by means of a Wenner salinity bridge. As the bridge was 

 calibrated by using samples whose salinities were determined by 

 silver-nitrate titration, the accuracy of the salinity measurements is 

 limited to that of the silver-nitrate titration method or about 

 ±0.02 °/oo in salinity. However, the precision of the salinities is 

 better than that and of the order of about ±0.005 °/oo. For the 

 most part they have been tabulated to the nearest 0.01 °/oo. During 

 routine salinity runs, the bridge was standardized each tenth to thir- 

 teenth sample in each of the cells with substandard sea water from 

 an oil-sealed carboy. At least once during each run and usually 

 oftener, Copenhagen standard sea water was measured as an un- 

 known to permit fuial adjustments of salinities for each survey. These 

 salinity adjustments were as follows: 



First and second cruises -1-0.01 /oo 



Third cruise No correction 



Fourth cruise -fO.Ol °/oo 



Post season cruise , parts 1 and 2 No correction 



55 



