during the Quarter ending September 30, 1848. 367 



quarter was 4*5 grains, which is 0*2 grain less than the average 

 for the seven preceding years. 



The additional weight of water required to saturate a cubic 

 foot of air was 1 *1 grain. The average value for the seven pre- 

 ceding yer.rs was 1*0 grain. 



The mean degree of humidity of the atmosphere for July 

 was 0-762, for August was 0*797, and for September was 0*795. 

 The averages for the seven preceding years were 0*780, 

 0*804, and 0*842 respectively. The value for the quarter was 

 0*785, which is 0*024 less than the average for these years. 



The mean elastic force of vapour for the quarter was 0*411 

 inch, which is 0*026 less than the average for these years. 



The mean reading of the barometer at Greenwich for July 

 was 29*836 inches, for August was 29*732 inches, and for 

 September was 29*832 inches; these values are 0*041 inch 

 above, 0*065 inch below, and 0*021 inch above respectively the 

 averages for the seven preceding years. The mean value for 

 the quarter was 29*797 inches, which is of the same value as 

 the average for the seven preceding years. 



The average weight of a cubic foot of air under the average 

 temperature, humidity, and pressure, was 527 grains; the 

 average for the seven preceding years was 526 grains. 



The rain fallen at Greenwich in July was 2*1 inches; in 

 August was 4*6 inches ; and in September was 2*4 inches ; the 

 average amount for the seven preceding years was 2*3 inches 

 in July, 2*7 inches in August, and 2*2 inches in September. 

 The amount fallen in the quarter was 9*1 inches, which is 1*9 

 inch greater than the average for the seven preceding years. 

 The average fall of rain during this quarter, as derived from 

 the observations since the year 1815, is 7 inches. In the 

 year 1824 the fall of rain in the quarter ending September 30 

 was 9 inches, in 1828 it was 12*5 inches, in 1829 it was 11 

 inches, and in 1839 it was 10*5 inches. The total amount of 

 rain fallen this year till September 30 was 24*3 inches ; in 

 1841 it was 21-2 inches; in 1842 it was 14*2 inches; in 1843 

 it was 17*5 inches; in 1844 it was 16*2 inches ; in 1845 it was 

 16*6 inches; in 1846 it was 17*5 inches; and in 1847 it was 

 11*6 inches. So that the fall of rain this year exceeds that in 

 1841 by 2*7 inches; in 1842 by 9*7 inches; in 1843 by 6*4 

 inches; in 1844 ! by 7*7 inches; in 1845 by 7*3 inches ; in 

 1846 by 6*4 inches ; and in 1847 by 12*3 inches. The excess 

 of the fall of rain this year over the average for the seven pre- 

 ceding years is 7*5 inches. 



In the years 1824 and 1828 the depth of rain fallen to the 

 end of September exceeded 23 inches; and in the years 1829 

 and 1839 the amount collected exceeded 20 inches. So large 



