112 
as the former embrace a longer period. This will be done 
sufficiently well by giving the first three sets -weights of 3 
each and the Milan set a weight of 2. If we perform this 
operation and then take the mean, we obtain as under : 
Proportional rainfall inequality, as exhibited by series of 
8 years. 9 years. 10 years. 11 years. 12 years. ISyears. 14 years 
“wrightedtsabf™”’’} 2 3-00 2-09 1-94 3-52 2-81 2-92 
A maximum corresponding to 9 years, and a still greater 
one, corresponding to 12 years, is thus exhibited, each of 
these being recorded at three stations out of four. 
The proportional numbers indicated are not large, but it 
must be remembered that it is the mean difference for all 
the years that is given, and that the maximum and minimum 
rainfall will represent differences above and below the mean 
which will each be about double the numbers recorded 
above. 
10. Regarding the rainfall values as representing the 
meteorological result of the sun’s action, let us now compare 
these with declination-range values, which may be taken to 
represent the sun’s magnetic effect. Professor Loomis has 
compiled (American Journal of Science and Arts, Second 
Series, Yol. L., page 153) what seems to be a very good 
table, exhibiting a set of yearly values of magnetic declina- 
tion-range extending, with slight breaks, from 1777 to 1868. 
Let us take this table and treat it precisely as we have 
treated the rainfall, except that it does not seem necessary 
to make any attempt at equalisation such as that made in 
article 8. 
We thus obtain the following result : — 
Proportional declination-rango inequality, as exhibited by series of 
8 years. 9 years. 10 years. 11 years. 12 years. 13 years. 14 years. 
^'""ToVrague^""''^} 3*37 3’39 10’07 4*66 9*33 4-09 4’98 
Here we have decided maxima corresponding to 10 and 
12 years. The result is thus not unlike that which has been 
derived from rainfall observations where the maxima cor- 
respond to 9 and 12 years — indeed we could hardly expect 
a more perfect correspondence between the two, bearing in 
