634 Proceedings of Royal Society of EdAnburgii. [mm. 
Considering the question of the maximum range of variation of 
rainfall in selected periods, and taking the average of the seven 
gauges, it is seen that in the period under review the maximum 
annual rainfall was 76 '47 inches and the minimum 49*62 inches, 
or, respectively, a variation of 22*4 per cent, above and 20 '6 per 
cent, below the mean of the seven years, namely, 62*51 inches; or 
17*6 per cent, above and 23*6 per cent, below the calculated mean 
annual rainfall over a long period, namely, 65 inches. 
If the shorter period of one month is taken, the range of varia- 
tion is, naturally, found to be very much greater, as is shown in 
the table below, in which the figures for each month of the year 
are given. The comparative regularity of the amount of rainfall 
during the month of October is noticeable, and also the great range 
of variation in the rainfall for March. 
Average of 7 Gauges. 
Maximum 
Minimum 
Per- 
centage 
Per- 
centage 
Month. 
Average 
Rainfall 
of 7 years. 
Maximum 
Rainfall 
recorded. 
Minimum 
Rainfall 
recorded. 
Rainfall 
above 
Average. 
Rainfall 
below 
Average. 
above 
Average. 
Maximum. 
below 
Average. 
Minimum. 
Inches. 
Inches. 
Inches. 
Inches. 
Inches. 
Per cent. 
Per cent. 
Jany. 
4*59 
6-83 
2-51 
2-24 
2-08 
49 
45 
Feb. 
3*99 
6*32 
1-95 
2-33 
2-04 
58 
51 
March 
4*45 
9-12 
0-79 
4-67 
3-66 
105 
82 
April 
4*58 
6-39 
2-31 
1-81 
2-27 
40 
50 
May 
3-38 
6-45 
0-75 
3-07 
2-63 
91 
78 
June 
4-45 
7*75 
1-63 
3-30 
2-82 
74 
63 
July 
4-01 
674 
1-64 
2-73 
2-37 
68 
59 
Augt. 
5*80 
11-29 
2-46 
5-49 
3-34 
95 
58 
Sept. 
6-04 
8-31 
4*14 
2*27 
1-90 
38 
31 
Oct. 
6*02 
7*46 
4-49 
1-44 
1-53 
24 
25 
Nov. 
6*44 
12-66 
2-46 
6-22 
3*98 
97 
62 
Dec. 
8 76 
62*51 
14-09 
2-97 
5-33 
5-79 
61 
66 
This suggests the investigation of the monthly distribution of 
rainfall throughout the year, and in the following table the result 
is given for each year and for the average of the seven years. The 
rainfall for each month in any year is stated as hundredth parts of 
the total rainfall for that year, still taking the average of the seven 
gauges. This table also brings out the comparative regularity of 
the rainfall of October in relation to that of the whole year. 
