1836.] 



variations of the Barometer. 



363: 



and further we have the following from the Register kept at the Assay 

 Office in Calcutta, and published in the Journal of the Bengal Asiatic 



Society : 



1832 1833 1834 1835 Mean Diff. 



January .... 30.071 30.095 30.066 30.041 30.068 —,050 



February 29.992 30.013 30.036 30.032 30.018 —,042 



March 29.921 29.904 29.934 29.965 29.928 —,079 



April 29.814 29.809 29.845 29.918 29.847 —088 



May 29.716 29.661 29.663 29.727 29.692 —,139 



June 29.573 29.613 29.574 29.605 29.591 —,207 



July 29.532 29.577 29.607 29.531 29.562 —,238 



August 29.522 29.643 29.593 29.635 29.598 —,249 



September.. 29.713 29.696 29.722 29.746 29.719 —,153 



October 29.898 29.904 29.880 29.870 29.888 —,047 



November. .. 30.055 30.029 30.065 30.069 30.054 —,016 

 December.... 30.045 30.058 30.091 30.082 30.069 —,007 

 A mere glance, at either of the above tables, shews us that a law of 

 some sort does exist, which it is important should be investigated. We 

 notice that the mean height of the barometer at 10 a. m. at the 

 level of the sea, and at the temperature of 32° Fahrenheit, Inches. 



at Madras. = 29.946 



Ditto at Calcutta, 29,835 + ,019* = 29.854 



Difference ,092 



We notice, further, that the barometer arrives at the maximum, both 

 at Madras and Calcutta, about the middle of December, and at its mini- 

 mum on or about the 1st of July. On inspecting the column " difference," 

 which, it will be understood, is the difference between the Madras and 

 Calcutta results, it is evident that some law, more or less simple, governs 

 the two results, which it is likewise of importance to discover. The 

 direction of the wind, and its consequences on the barometer, as given 

 above, will evidently not reconcile the Madras results ; take for in- 

 stance the month of December, when the N. E. wind prevails during 

 16 hours of the day, and the E. wind during the remaining 8 hours ; 

 here we get 



Inches. H. Inches. 



Cor. for E. wind === +,055 X 16 = 880) 



_ N.E. — = 4-,lU X 8 = 888 S T 24 = 

 which correction being applied to the mean height, gives 30,020 for 

 the barometer in December, differing from the actual observations 

 ,098. With regard to the Calcutta results, I need hardly remark that 

 they can in no wise be reconciled by the above corrections. I had pro- 

 ceeded thus far and was about to give up the matter, when it occurred 



* This is to reduce the observations to the level of the sea. 



