PROCESSING PROCEDURES 



master plot or individual graph may be made 

 up directly from the equation 



■i w ' u ~~ 



KC_ 



In the illustration, figure 6, T^ is plotted along 

 the abscissa and C along the ordinate. By 

 substituting various values of Tu and T^—t,, 

 in the above equation, C may be evaluated. 

 Since the lines of Ttc—t,^ are straight, only one 

 value at either side of the graph need be cal- 

 culated. The constants in the example arc 

 Vo=l\5 and 7^=6100. The index correction, 

 7, at calibrated values of T,', is plotted using 

 the C scale along the ordinate. 



9 _ 10 



11 j2 13 14 15 16 17 



Figure 6. — Portion of individual unprotected thermometer 

 correction graph giving C and / for values of ?"„ and 

 7"„-<.. 



To use the graph the values of C and 7 may 

 be read directly. For example, when 7"^= 1 1 .83° 

 C. and r„-<„= 11.05° C, C is found to be 

 -0.23° C. and 7= -0.02° C, or Ar„= -0.25° 

 C. 



The other recommended individual unpro- 

 tected thermometer correction graph is shown 

 in figure 7. Here T'^, and T^—tu are the 

 abscissa and ordinate of the graph. The values 

 of C are calculated for combinations of T'^ and 

 Tu,—tu from the unprotected thermometer cor- 

 rection formula. In preparing the graph, val- 

 ues of 7 are added to C at points of calibration 

 ot T'u- A correction graph constructed in this 

 fashion gives AT directly but requires an indi- 

 vidual graph for each unprotected thermometer. 



Figure 7. — Portion of individual unprotected thermometer 

 correction graph giving aT for values of T^, T^—la. 



The example shows that when V„= 115° C, 

 7v = 6100, r;=11.83°C.,andT„-<„=11.05°C., 

 then AT is -0.25° C. 



DEPTH 



A rough estimate of the depths at which the 

 water bottles of a cast are reversed in the sea 

 may be obtained from wire angle (the angle the 

 wire makes with the vertical) at the sea sur- 

 f;icc, and the length of wire to each bottle. 

 However, this method assumes that the curva- 

 t urc of the wire below the surface is kno\vn, an 

 assumption which is not valid to great depths. 

 The method is satisfactory only for depths of 

 less than 100 meters with large wire angles, and 

 to several hundred meters with angles less than 

 5°. 



The customary method of determining depth 

 of sampling when the wire angle is greater than 

 5° is by comparing the corrected readings of the 

 protected and unprotected deep-sea reversing 

 thermometers. Depth is determined from the 

 difference between the corrected readings in 

 accordance with a formula by G. Wiist (1 933) {9) : 



D= 



PmQ 



where, 



D = depth in meters, 



?'„ = corrected reading of the unprotected thermom- 

 eter, a function of both temperature and 

 pressure, 



7'„ = corrcctod reading of the protected thermometer, 

 a function of temperature only, 



