82 



data collected at the 226 stations occupied during the season and on 

 the post-season cruise are presented in the oceanographic table in 

 tliis bulletin. 



The equipment and methods of measurement were the same as in 

 1938. Calibration titrations were performed by James F. Flannery, 

 seaman, first class. Routine salinity bridge measurements were made 

 by Flannery, Albert H. Hauser, seaman, first class, and Leonard T. 

 Quattlebaum, seaman, second class. Other assistants in the obser- 

 vational work were Thomas C. Crabe, yeoman, second class, and 

 Henry A. Minard, surfman. At the 201 stations occupied during 

 the season the extent and nominal depths of the serial observations 

 of temperature and salinity were the same as in 1938. At all stations 

 on the post-season cruise the measurements extended to as near 

 bottom as was practicable. 



As in years past, a program of intercomparison of the reversing ther- 

 mometers was carried out tlu-ough periodic shifts in thermometer pairs 

 in order to check on the functioning of these instruments. In all, 1,414 

 individual comparisons were investigated, the probable differences be- 

 tween the corrected readings of a pair of thermometers varying among 

 the different groups from 0.003° to 0.020° C. and being 0.01 1° C. for the 

 entire 1,414 comparisons. The observed temperatures are therefore 

 considered to be accurate to 0.01° C. 



An error in standardization of the salinity bridge affecting the 

 fourth map and the post-season cruise was introduced by a question- 

 able intermediate- or sub-standard but was detected and verified by 

 the careful titration of 85 actual sea-water samples. These corrections, 

 as well as the final standardization adjustments for the rest of the 

 season, have been made before tabulation of the data and construc- 

 tion of the current maps. Near the end of the post-season cruise, 

 1 of the cells of the salinity bridge became inoperative tlii'ough 

 short-circuiting of its connections by a brass chip in the oil bath. 

 Following the return of the equipment to the shore laboratory the 

 bridge was disassembled, cleaned, and reassembled and its calibration 

 curve then redetermined by numerous measurements, by both bridge 

 and titration methods, on 7 oil-sealed carboys of actual sea water, 

 approximately equally distributed over the salinity range of 32.6°/oo 

 to 36.6%o. The calibration curve resulting is expressed by the 

 equation: 



^=10100.637/(204.475 + i\/) -4.671 



where S represents salinity in parts per thousand and M represents the 

 resistance, in ohms, of the X arm of the salinity bridge as given by 

 the dial readings at balance. The bridge measurements, which were 

 made in the same manner as routine measurements are made at sea, 

 had an uncertainty of ±0.003°/oo to ±0.004%o salinity. This is 

 regarded as a measure of the precision of the method, the accuracy of 



