T' = The uncorrected temperature read- 

 ing of the main protected reversing 

 thermometer. 

 /=The index correction for errors in the 

 main protected thermometer scale. 

 This is given on the caUbration 

 sheet or card and must be inter- 

 polated for the temperature reading 

 (7") as closely as the calibration 

 sheet will permit. 



/t — lOu 

 tion for the thermal expansion of 

 the thermometer system, where 



Fo=The volume of mercury below the 

 0° C. mark determined at 0° C. in 

 the reversed main thermometer, 

 expressed in degrees Celsius. It is 

 given on the calibration sheet. 

 /=The temperature reading of the aux- 

 iliary thermometer corrected for 

 index errors. The corrections are 

 given on the calibration sheet. It 

 is the temperature at which the 

 protected reversing thermometer is 

 read. 



K=The reciprocal thermal coefficient of 

 expansion of the thermometer sys- 

 tem. It is a constant dependent 

 upon the type of glass of which 

 the thermometer is made. The 

 it-value is given on the calibration 

 sheet. Since most reversing ther- 

 mometers are read to hundredths 

 °C., the correction is desired to the 

 same accuracy. This accuracy can 

 be obtained when the denominator 

 of the fraction is taken to be K-100. 



An example of correcting a protected ther- 

 mometer is shown as follows : 

 Given : 



9.33° C. (uncorrected main thermometer 



as shown on the A-sheet). 

 20.2° C. (uncorrected auxiliary thermom- 

 eter as shown on the A-sheet) . 



From the calibration sheet for this thermom- 

 eter we find : 

 Fo=96°. 

 <=20.2° C.± the auxiliary thermometer 

 index correction (in this case +0.7° 

 C.)=20.9°C. 



K=Q100. 



/=— 0.01° C. (index correction for the 

 main thermometer at 9.33° C). 



H. O. 607 



Find: 



^_ (9.33 + 96) (9.33-20.9) 



6100-100 

 ^^ (105.33) (11.57) 



6000 

 C=-0.20°. 



Find: 

 T„=T' + C+/. 



7'„=9.33°+ (-0.20°) + (-0.01°). 

 r„=9.12°. 



3-5 Correcting the UNPROTECTED Ther- 

 mometer. — The unprotected thermometer is 

 corrected by the following formula: 



Tu=T\+C+I 



where the symbols are defined as: 



Tu = The corrected reading of the unpro- 

 tected reversing thermometer, a 

 function of both temperature and 

 pressure. 

 T'„=The uncorrected temperature reading 

 of the main unprotected reversing 

 thermometer. 

 /=The index correction for errors in the 

 main unprotected thermometer scale. 

 This is given on the calibration sheet 

 or card and must be interpolated for 

 the temperature reading (T' u) as 

 close as the calibration sheet will 

 permit. 

 ^^ (T\+VaUT^-t,) ^j^.g .g ^^^ ^^^^^^_ 



tion for the thermal expansion of the 

 thermometer system, where 



Fo=The volume of mercury below the 

 0° C. mark determined at 0° C. in 

 the reversed main thermometer, ex- 

 pressed in degrees Celsius. It is 

 given on the calibration sheet. 

 rK,= The corrected value of the protected 

 reversing thermometer reading, (the 

 true water temperature at depth of 

 reversal) . 



/„=The temperature reading of the unpro- 

 tected auxiliary thermometer cor- 

 rected for index errors. The correc- 

 tions are given on the cahbration 

 sheet. It is the temperature at 

 which the unprotected reversing 

 thermometer is read. 



K=The reciprocal thermal coefficient of 

 expansion of the thermometer sys- 

 tem. It is a constant which is de- 

 pendent upon the type of glass with 



31 



