in the table of oceanographic data have a probable error of 

 ±0.01°C. 



Routine measurements of salinity were made, as in previous 

 years, with a Wenner salinity bridge using a substitution method. 

 From measurements and tests of the instrument prior to the be- 

 ginning of the 1956 field work it was concluded that there was no 

 need for a redetermination of its calibration curve. Water from 

 an oil-sealed carboy of sea water was used as a working standard 

 of salinity for the routine measurements. At least twice during 

 each run samples of Copenhagen normal sea water were measured 

 as unknowns. At the end of each survey these measurements of 

 Copenhagen water were used to compute any necessary corrections 

 to the salinities of the samples measured during the survey. At the 

 beginning of the season Copenhagen water of the batch P 17 was 

 used. Samples of Copenhagen water of the batch P 2 2 were also 

 measured as unknowns to get the conductivity-salinity relation- 

 ship of this batch in terms of the batch P 17 , thus enabling a shift 

 to batch P 22 as the reference standard at the beginning of the 

 3rd survey. For the three surveys made during the season the 

 corrections did not exceed 0.005 °/ o and no corrections have been 

 applied. The correction for the post season cruise was+0.006°/oo 

 and corrections have been applied in the table of oceanographic 

 data. The dynamic topography of the Bonovista triangle shown 

 in figure 15 however, has not been corrected and the dynamic 

 heights shown in this figure are consequently 4 mm too high. 

 The calibration curve of the salinity bridge is determined by the 

 measurement of samples of sea water whose salinities are known 

 from silver nitrate titration. The accuracy of the salinities deter- 

 mined by the bridge is therefore no better than the accuracy of 

 the silver nitrate titration method used in determining the cali- 

 bration curve. The precision of the bridge measurements, how- 

 ever, is much better and is about ± 0.005 °/oo in salinity. 



37 



