HEIGHT IN THE ATMOSPHERE AT DIFFERENT SEASONS IN THE YEAR. 



495* 



days on the Faulhom (Poggendorff, xxvii. p. 354), compared with those at 

 Geneva and Zurich, I have obtained graphically the following results : — 



For the Faulhom and Geneva, we deduce from the ranges by Eq. (7), 



dx, _ 3.9 

 dC! ~ 



2.85 



= 1.4. 



By the preceding Table : 



Maximum; ^,= 1.77 C = 2.23 -^^ = 0.79 



c 



Minimum ; x, = 0.22 C = 0.23 



G 



;^=0.95 



It is quite evident that these results exhibit only a very rough degree of con- 

 formity with the computed value, and that the maximum and minimum epochs 

 are not symmetrically shifted. It would be easy to point out the causes of these 

 discrepancies, amongst which must be reckoned the very short periods during 

 which this highly interesting class of observations has been continued, and the 

 want of symmetry in the forms of the diurnal curve where the stations are very 

 widely separated. This investigation may, perhaps, induce a more careful ex- 

 perunental inquiry into the subject under favourable circumstances. The ele- 

 gant relation of the velocities of displacement of the epoch at the superior sta- 

 tion, and of the epochs of the differential curve, is at least worthy of notice ; the 

 ratio of velocities being so low as 1 to 19 when the ranges at the two stations are 

 as 20 to 21 ; whilst it rises to 64 : 100, or 2 : 3 nearly, when the ranges are (as 

 in Saussube's observations at the Col du G^ant and Geneva) as 2 to 5. 



VOL. XIV. PART II. 4 M * 



