INEQUALITY IN RAINFALL. 165 



7. Through the kinduess of Mr. Whipple^ Director of 

 the Kew Observatory, I have received copies of those 

 catalogues of raiufall which he has himself made use of in 

 a paper which was recently communicated to the Royal 

 Society (January 8, 1880). Of these Paris, Padua, Eng- 

 land, and Milan form the most extensive series, that of 

 Paris embracing i6i years, Padua 154, England (Symons^s 

 Table) 140, Milan 115, Mr. Whipple has likewise 

 furnished materials by which the labour of applying the 

 process in hand to these series will be much abridged ; and 

 he has kindly allowed me to make use of these. I will 

 therefore apply the process to these four stations. 



8. Let us begin by grouping the Paris yearly values 

 into series of 8. We thus obtain the following final num- 

 bers expressed in centimetres — 5I'4^47-5j 457, 48'7^ 51*1^ 

 49"8, 46*5, 47'2, the mean being 48*5. From these we 

 obtain the following series of differences : — 



4-2-9, — I'O, — 2"8, +0-2, +2"6, +i'3, — 2-0, — 1'3. 



In order to diminish the effect of accidental fluctuations, 

 let us equalize this series of differences by taking the mean 

 of each two. We thus obtain — 



-|-o-8, H-i"o, — 19, — 1'3, +i'4, +i'9, — o'4, —17. 



If we now add these together, without respect of sign, and 

 divide by their number (8), we obtain 1-3 as the mean 

 departure from the mean of the whole ; and bringing this 

 into a proportional shape by dividing it by the mean rain- 



l"20 



fall (48-5), wc obtain -^ = 2-68 per cent. 



9. These explanations will enable the reader at once to 

 perceive the principle of construction of the following 

 Table:— 



