VIII. 



TABLES 



FOR COMPUTING DIFFERENCES OF ELEVATION FROM BAROMETRICAL OBSERVATIONS, 

 BASED ON BESSEl's FORMULA. 



Br E. PLANTAMOUR. 



[These Tables, computed by Professor E. Plantamour, Director of the Observatory at Geneva, 

 Switzerland, are found in Vol. XIII. Part 1, of the Memoires de la Socie'te de Physique, ^c. de Geneve, 

 p. 63, together with the following explanations.] 



In No. 356 of the Asironomische Nachrichten, Bessel published a paper on the 

 measurement of heights by means of the barometer, in which he deduces a formula 

 which contains a factor depending on the humidity of the air. This formula is : 



, P (ff).lI'—Ur. 0.002561 ,^ 0.0279712 T — 0.0000625826 Tn 



^^SF=i:li+XT)-[i-'^TPF- J' 



where the various quantities have the following signification : — 



h being the elevation of the lower station, and 



h' the elevation of the upper station above the level of the sea, 



a = the radius of the Earth, 



jj ah 



a + /i" 

 P =: the weight of the atmosphere at the lower station, 

 P' =z the weight of the atmosphere at the upper station, 



the unit of weight assumed being the pressure of a column of mercury 

 D 72 



