132 
Total Amount of 
Hours. 
Rainfall. 
Frequency. 
1, 2, 3, ... 
1-929 
76 
4, 5, 6, ... 
2-816 
88 
7, 8, 9, ... 
3-123 
100 
10, 11, 12, ... 
2-642 
113 
13, 14, 15, .... 
2-562 
106 
16. 17, 18, ... 
2-916 
99 
19, 20, 21, ... 
3-545 
100 
22, 23, 24, .... 
2-321 
72 
Projecting these numbers on ruled paper, and drawing a 
curved line through the points thus laid down, we obtain a 
well-marked curve, having two maxima and two minima, 
which occur at the following hours : — 
Principal maximum at 
X 
oo 
a.m. 
Secondary „ „ 
8h. 
p.m. 
Principal minimum ,, 
2k. 
Secondary „ „ 
Ub. 
a.m. 
This curve has no similarity to that of daily temperature, 
but has a strong resemblance to the curve of diurnal variation 
of the barometer, with a difference of about two hours in the 
times of occurrence of the maxima and minima. The regular 
diurnal variations of the barometer in this latitude are, how- 
ever, so small that it is hardly conceivable they can produce 
the great differences in the amounts of rain falling at different 
periods of the day as indicated by Mr. Bates’s observations. The 
curve of daily variation of the intensity of atmospheric electricity 
has also strong points of resemblance to the rain-curve, but its 
night minimum is the principal one, and most meteorologists 
will probably regard variations of intensity of atmospheric 
electricity as consequences rather than causes of the changes 
in the amount of condensed vapour precipitated in the form 
of rain. No other meteorological phenomenon is at present 
known having diurnal variations similar to those of the rain- 
fall ; but if we turn to the phenomena of terrestrial magnetism, 
