26 Meteorological Observations on Parisnath Hill. [No. 1. 



rections have served to eliminate. Between the hours 8 and 9 a. m. 

 on the 3rd, only, have the corrections failed to restore the course 

 to that regularity, which prevails on the two other days, and the baro- 

 metrical pressure on the Hill at those hours appears still too high ; 

 but as any further alteration would only have been arbitrary, it was 

 not attempted. 



The general conformity of the variation in the hourly weight with 

 the course indicated by the real mean temperatures having thus 

 been established, it remains to be proved, that the relation between 

 the hourly weights strictly corresponds to the course prescribed by 

 theory, with regard also to the barometrical pressure. 



The shortest way to ascertain this, would be, to compute the 

 weight of the column of air for every hour, and to compare the va- 

 lues thus theoretically obtained, with the observed barometrical 

 differences. 



Neglecting for the present the influence of the watery vapour 

 contained in the atmosphere, the weight of the column of air be- 

 tween the stations, measured by a column of mercury of an equal 

 basis at 0° C. would be expressed by the following formula : 



H. a b_ 

 S == p" a+t B 

 where S stands for the weight. 



H gives the height in English inches (Log H = 4.6854873) ; 

 p is the specific gravity of Mercury, that of the atmospheric air, at 

 0° C. and under the normal pressure being taken as unity. Taking 

 13.59593* as the specific gravity of Mercury, and 0.001290445f as 



* Regnault, in Poggendorff's Annalen Vol. LXXIV. 1849. 

 t The weight of 1 Litre atmospheric air in Latitude <f> and the height a above 

 the sea level is 



1—0.0025935 cos 2 0. 

 1. grm 292753 l + 2a ~~ 



IT 

 From Regnault's determination, Poggendorff's Annalen Vol. XCYIII. page 178. 

 The latitude of Calcutta is 22° 33', and that of Parisnath hill 23° 57' 37". 

 Taking the mean of both, 23° 15' and neglecting the correction for the elevation 

 above the sea level, which is only 18 feet at Calcutta, the weight of 1 Litre air 

 at the latitude 23° 15' will be 1. grm 290445 j Log. = 0.1107395. 



