544 



Royal Society : — 



Oct. 



1862 



Nov. 



>f 



Dec. 



a 



Jan. 



1863 



Feb. 





March 



i » 



April 



)} 



May 



>) 



June 





July 



>t 



Aug. 



>) 



Sept. 



i> 



Windsor, N.S. 



Oct. 



Nov. 



Dec. 



Jan. 



Feb. 



March 



April 



May 



June 



July 



Aug. 



•832 



•766 



1-010 



1-057 



1-432 



1-396 



1-023 



•796 



•720 



•755 



•952 



•985 



1863 1-033 



„ '949 



„ l-iio 



1864 1-125 



? 



............ 1-416 



1-026 



-985 



-799 



-885 



(-862) 



The last step in the reductions consisted in expressing the vari- 

 ations, both diurnal and annual, atKew, and the annual variations at 

 Windsor, by the first two terms of an harmonic series. 



In the case of the diurnal variations at Kew, the amplitudes of 

 the two terms were nearly equal, but the epoch was much more 

 uniform in its values (whether in comparing one year with the other 

 or in comparing one month with another in the same year) for the 

 second term than for the first. 



In the case of the annual variations, the amplitude of the second 

 term at Kew was almost inappreciable, while at Windsor it was greater 

 than that of the first term. 



December 12. — Lieut, -General Sabine, President, in the Chair. 



The following communication was read : — 



" On a supposed Connexion between the Amount of Rainfall and 

 the Changes of the Moon/' being an extract of a Letter from J. H. 

 N. Hennessey, Esq., First Assistant on the Great Trigonometrical 

 Survey of India, to General Sabine, H.A., Pres. ft.S. 



Allow me now to say a few words in connexion with the enclosed 

 paper. There appears to prevail a belief, more or less popular, to 

 the effect that more rain falls at " the changes of the moon " than 

 on the intermediate days of a lunation. As I happened to possess 

 a record of the rainfall at the office of the Superintendent of the 

 Great Trigonometrical Survey of Mussoorie, extending over thirteen 

 consecutive years, I obtained Colonel Walker's permission to make 

 use of the register, in connexion with this popular belief. 



The results tabulated have been obtained by employing an average 

 daily fall as the means for comparing the fall at "the changes " 

 with that at intermediate intervals. The method of calculation 

 adopted is explained in the footnote to the Table. The annual 

 average result may be stated thus : — 



inch. 

 At " the changes " of the moon the mean daily fall of rain is 0-466 

 Between " the changes " of the moon the mean daily fall is . . 0-525 



which is in opposition to the popular belief on the subject. I en- 



