chapter 3. Only brief descriptions of the 

 cohimns are given here. 



14-41 LEFT THERMOMETER. 



(a) Therm. No. — The thermometer number is 

 the manufacturer's number and usually is found 

 inside the reversing thermometer case on the 

 metal band supporting the main and auxihary 

 thermometers. This number must be carefully 

 recorded as it is the only means of identifying 

 each thermometer. 



(6) Main (T'). — Record in this column the 

 reading of the main thermometer. Allow suf- 

 ficient time for the whole thermometer to come 

 to air temperature before reading. The main 

 temperature must be read to the nearest 

 hundredth of a degree Celsius. 



(c) Aux. (t) . — Immediately after reading the 

 main thermometer, the auxiliary thermometer 

 must be read to the nearest tenth of a degree 

 Celsius and the value recorded in this column. 

 It is advisable to write the figures fairly small 

 and close to the lower line in order to leave room 

 to write the corrected reading above. The 

 corrected reading (t) is obtained by applying 

 the auxiliary index correction, given on the 

 thermometer's calibration sheet, to the ob- 

 served value. 



(d) Va- — The Vo is the volume of mercury 

 below the 0° C. mark at the temperature of 

 0° C. in the reversed main thermometer, ex- 

 pressed in degrees. This value is obtained from 

 the thermometer's calibration sheet. 



(f) /. — / is the index correction for errors in 

 the main thermometer scale. This value is 

 obtained from the thermometer's calibration 

 sheet. It is read for the temperature of reversal 

 or as close thereto as the table of calibration will 

 permit. 



(./) C. — C is the correction for thermal expan- 

 sion of the thermometer system after reversal. 

 See chapter 3 for the formulas and methods for 

 computing this value. 



in) Tu,. — T^ is the corrected reading of the 

 protected reversing thermometer. This value 

 is obtained by adding algebraically the values 

 given in the Main, /, and C columns. 



14 42 RIGHT THERMOMETER.— Unpro- 

 tected reversing thermometers are customarily 

 placed on the right and are distinguished by 

 placing the letter U after the manufacturer's 

 number. 



(a) Therm. No. — Same directions as for Left 

 thermometer. 



(6) Main (7" or T"„). — Same directions as for 

 the Left thermometer. T' is the symbol used 

 in the correction formula for protected ther- 

 mometers and T\ is the symbol used in the 



correction formula for unprotected thermome- 

 ters. 



(c) Aux. (t or 4) • — Same directions as for the 

 Left thermometer. The corrected reading (t) 

 is used for the protected thermometers. The 

 corrected reading (<„) is used for unprotected 

 thermometers. 



(d) Vo- — Same directions as for the Left 

 thermometer. 



(e) I. — Same directions as for the Left 

 thermometer. 



(J) C. — Same directions as for the Left ther- 

 mometer. See chapter 3 for the formulas and 

 methods for computing this value. It is im- 

 portant to remember that protected and unpro- 

 tected values are computed by different 

 formulas. 



(g) Tu, or Tu- — T^ is the corrected reading of 

 the unprotected reversing thermometer. T^ 

 is the corrected reading of the protected re- 

 versing thermometer. Either value is obtained 

 by adding algebraically the values in the 

 Main, I, and C columns. 



14-43 Average Ty,. — When both right and 

 left thermometers are protected the value 

 recorded in this column is the average of the 

 two corrected readings {Tu,)- When there is a 

 single protected, or a protected paired with an 

 unprotected, the corrected reading {T„) given 

 for the Left termometer is copied into this 

 column. After completion of the depth cal- 

 culations, these entries are copied on the E- 

 sheet, into the column headed Ty, °C., along 

 with their corresponding serial numbers and 

 accepted depths. 



14-44 Diff. (r„ - T„) .—Entries are made in 

 this column only where there are paired pro- 

 tected and unprotected thermometers. Each 

 value entered here is the difference between 

 the Ty, and the corrected unprotected reading 

 Tu in the preceding column. 



14-45 Corr. — The correction value entered 

 in this column is obtained from the depth 

 anomaly (AZ) graph for the unprotected 

 thermometer. Instructions for constructing 

 and using AZ graphs are given in chapter 3. 

 When AZ graphs are not used and the ther- 

 mometric depths are determined by direct 

 calculations, no entries need be made in this 

 column. 



14-46 Thermometric Depth (Z) .—The Ther- 

 mometric Depth (Z) is the algebraic sum of 

 the 2 preceding columns times 100. It is the 

 value, Z, used in determining the accepted 

 depth bjr the L-Z method. Instructions for 

 computing thermometric depths by formula are 

 given in chapter 3. 



142 



H. O. 607 



