BAROMETRICAL TABLES. 



XXXVll 



Corrections to be applied to the tabular values of Table 45 in order to use them 

 zvhcn the temperature of the attached thermometer is below 0° Centigrade. 



Example: 



Observed height of barometer, 763.17' 



thermometer, — 12° C. 

 Numerical value of the reduction for + 12° C. 

 Correction for temperature below 0° C. 

 Reduction for — 12° C. 

 Observed height of barometer 

 Barometer corrected for temperature 



Temperature of the attached 



1.50 



+ O.OI 



+ 



I-5I 

 = 763.17 



764.68 



Table 46. Reduction of the mercurial column in U-shaped manometers with 

 brass scales to standard temperature. English measures. 



This is in reality an extension of Table 44 to the small differences in 

 height of the mercurial columns as determined with a U-shaped manometer 

 and is used especially in the calibration of instruments for upper-air Investi- 

 gations. Since the corrections are directly proportional to the observed height 

 of the mercurial column, they have been obtained by multiplying corrections 

 given In Table 44 by the appropriate decimal. They have been computed for 

 each inch of pressure from i inch to 20 inches, inclusive, and for intervals of 

 temperature of 2 degrees, from o" to 100° Fahrenheit. 



