1874.] 



the Periodicity of Rainfall. 



287 



some 7| per cent, of the annual fall. Excepting five years at Dehra and 

 two at Mussoorie, all the observations have been taken under my own 

 superintendence, so that 1 can vouch for their accuracy. Eejecting 

 decimal places as redundant, the rainfall is as follows (in inches) for 20 

 years at Mussoorie and for 13 years at Dehra : 



TABLE I. 



4. Adding to the fall in the epochal year ({. e. maximum or minimum) 

 the fall for one preceding and one succeeding year, we shall get what 

 may be termed three-year sums ; similarly, by including two years on each 

 side of the epochal year, we find Jive-year sums% : the results are as 

 follows : 



TABLE II. 



* Taken from a paper in 'Nature,' 1872, December 12, page 100, by Norman 

 Lockyer, Esq., F.E.S., &c. 

 t Site of rain-gauge shifted. 

 | ' Nature,' 1872, December 12. 



