330 



TABLE XXI 



This table is taken from Kaemtz's Lehrbuch der Meteorologie, Vol. II. p. 236. 

 To render it more useful, the first page, giving the corrections for Barometrical 

 Heights between 240 and 280 Paris lines, has been added. 



The values adopted by Kaemtz for reducing the Old French Barometer are the 

 following : — 



Let A = observed height in French lines. 

 " ^ = temperature of attached thermometer in degrees of Reaumur. 

 " m == expansion of mercury between and 80° Reaumur = 0.018018. 

 " i r= linear expansion of brass between and 80° Reaumur = 0.0018732. 

 The normal temperature of standard being = 13° Reaumur. 

 And the formula becomes, — 



, mx t — l (t — \3) 



• l + mXt 



The Table gives the corrections only for full degrees and for every fifth line ; but 

 the intermediate values can easily be found by an interpolation at sight. 



Example of Reduction. 



Observed height . . . . . . = 325.32 lines. 



Attached thermometer .....= 12.5Rtaumur. 



In the line beginning with 12°, and in the vertical column headed 325 lines, 

 we find, Correction for 12° = — 0.89 lines. 



Interpolation for 0°.5 = — 0.03 " 



And we have, 



Correction for 12°.5 = —0.92 " 



Observed height, 325.32 '' 



Correction for 12°.5, —0.92 " 



Height at the freezing point = 324.40 lines. 



124 



