586 Continuation of a Paper on Heights of Barometer, $c. [Sept, 



•235 



2 



3 



4 



5 



6 



7 



•221 



•223 



•22/ 



•216 



•218 



•217 



so that the first column would correspond with the left-hand column 

 of the former classification. North and south declination were then 

 put together, and the results came out thus : 



Days 



Average amount of variation 1 , 2 „ 

 from the mean, j 



The average was next taken for nine years, in which the declination 

 was at a medium, say between 26° and 21°, so that the first column 

 would nearly correspond with the second column of the former classifi- 

 cation ; the seventh column being, as before, that on which the decli- 

 nation was least. The years were 1814, 1815, 1816, 1817, 1824, 

 1825, 1826, 1833, 1834, and the results were: 



Days 



Average amount of variation "| 

 from the mean, J 



The average was again taken for nine years, in which the declina- 

 tion was least, viz. between 21° and 18°; that is to say, 1810, 1811, 

 1812, 1813, 1828, 1829, 1830, 1831, 1832. The first column, in 

 this case, would nearly correspond with the third in the classification 

 of the Calcutta barometer. The results were as follows : 



Days, •.••.••• 



Average amount of variation 

 from the mean, 



1 



2 



3 



f 4 



5 1 



6 



245 



•220 



•215 



•200 



•201 



•215 



7 

 •225 



1 



2 



3 



4 



5 



6 



206 



•214 



•212 



•221 



•228 



•225 



7 

 •230 



In this last case no increase of variation is perceptible towards the 

 maximum, but then the maximum did not usually exceed 20°, or at 

 the most 21°. 



I have as yet said nothing about the perigee, because it has been 

 proved in Europe that the perigee produces some effect on the weather. 

 "With a view to ascertain whether the effect produced was the same as 

 that occasioned by the increase of declination, I took the same varia- 

 tions of the London barometer, as before, for 24 years, and arranged 

 them in different columns according to the state of the moon's semi- 

 diameter on the days on which they were taken. The general aver- 

 age came out thus : 



}) 's i diam. 1000" 990" 980" 9/0" P60" 950" 940" 930" 920" 910" 900" 890" 

 Av. Var. Bar. -247 -227 -207 '229 -226 -219 -216 -214 -209 -224 -205 -218 '211 



Here there appears a tendency to an increase of variation with an 

 increase of semi-diameter ; but on examining the differences of the 

 Calcutta barometer, no such increase could be made apparent. It 

 remains, therefore, in doubt whether, in this climate, such an increase 

 does exist — or whether, owing to some mistake, yet undetected, 

 it has not been made apparent. I am inclined to the latter supposi- 

 tion — from this consideration — 1st, If no increase exists, no results 

 could be traced from it ; 2ndly, If an increase exists, though not, at 



