Ill 
of rainfall wliich. lie has himself made use of in a paper 
which was recently communicated to the Royal Society 
(January 8, 1880). Of these Paris, Padua, England, and 
Milan form the most extensive series, that of Paris em- 
bracing 161 years, Padua 154, England (Symons’ 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 numbers 
expressed in centimetres : — 51 ’4, 47’5, 4 5 -7, 48*7, 51*1, 49 ’8, 
46*5, 47‘2, the mean being 48*5. From these we obtain the 
following series of differences : — 
+ 2-9 - 1 -0 - 2-8 + 0-2 + 2-6 + 1-3 - 2-0 - 1*3 
In order to diminish the effect of accidental fluctuations, 
let us equalise this series of differences by taking the mean 
of each two. We thus obtain — 
+ 0*8 + 1-0 - 1-9 - P3 + 1-4 + 1-9 - 0*4 - P7 
If we now add these together, without respect of sign, and 
divide by their number (8), we obtain P3 as the mean 
departure from the mean of the whole, and bringing this 
into a proportional shape by dividing it by the mean rain- 
fall (48*5), we obtain 
1-80 
48-5 
= 2'68 per cent. 
9. These explanations will enable the reader at once to 
perceive the principle of construction of the following 
table : — 
Proportional rainfall inequality, as exhibited by series of 
English rainfall, \ 
Symons’ Catalogue. T 
8 years. 
9 years. 
10 years. 
11 years. 
12 years. 
13 years. 
14 years, 
2-63 
2-14 
1-55 
1-79 
3-15 
1-69 
2-57 
Paris 
2-68 
3-07 
L99 
2*65 
3-70 
2-57 
3*08 
Padua 
1-77 
3’62 
2 ’02 
1-47 
3-31 
3-52 
3*40 
Milan 
1-12 
3*22 
3*16 
1-78 
4*13 
3 '78 
2-49 
We ought to give the English, the Paris, and the Padua 
observations a somewhat higher weight than those of Milan, 
