TABLE XIX. 



THIS table has been calculated by using the following coefficients of dilatation : 



Brass, linear dilatation, from Laplace and Lavoisier for 100 C. = 0.0018782. 



Mercury, dilatation in volume, from Dulong and Petit for 100 C. = 0.0180180. 



Dilatation of the mercurial column for 100 C. . . . = 0.0161398. 



Dilatation of the mercurial column for 1 C. . . = 0.0001614. 



Observed height reduced to freezing point, 



H=h h (0.0001614). T=h h ( a -jy. 



The second term of this last formula is given by the table, when the temperature 

 1 and the height h of the barometer are known ; this correction must be subtracted 

 om the observed height A, whea the temperature is above freezing point ; it is to be 

 ided when the temperature is below zero, or freezing point. 



This table allows the barometrical heights taken at the highest summits, and in the 

 jepest mines, to be corrected. 



Examples of Calculation. 



mm. 



Barometer, observed height, ..... 567.49 



Temperature of the barometer, -}-12 .7. 



o nun. 



f for 10.0=0.912 

 Second page, 5 for 2.0 = 0.182 

 C for 0.7 = 0.064 



Total, = 1.158 

 Subtractive correction, ...... 



Barometer at zero, 



mm. 



Barometer, observed height, 454.17 



Temperature of the barometer, 7.8. 



First page, < 



o mm. 



for 7.0 = 0.514 

 for 0.8 = 0.059 



Total, = 0.573 



Additive correction, 



Barometer at zero, 



75 



