54 
Proceedings of the Boy at Society 
ftnd August IStli) were accompanied by thunderstorms. On nine 
days rain fell continuously, and on two there was continual snow. 
There were thus 8 per cent, of unsuccessful, and 92 per cent, of 
successful, predictions when the rainband was at its maximum. 
It was found that on twenty-eight- occasions D tt was < h. On 
eighteen of these no rain whatever followed for twelve hours, on 
four one, or at most two, slight showers followed. On four con- 
siderable rain, and on two a considerable amount of snow fell. There 
were thus 21 per cent, of erroneous, and 79 per cent, of success- 
ful, predictions when the rainband was its minimum of intensity. 
Table IV. gives a summary of all the predictions made from June 
to December 1882, with the fulfilments. These predictions were 
Table IY. 
June. 
July. 
Aug. 
Sept. 
Oct. 
Nov. 
Dec. 
Total. 
Rain predicted, 
17 
22 
20 
21 
20 
12 
13 
125 
, , followed, 
Per cent, fnl- ) 
filled pred, , ^ 
15 
20 
12 
12 
16 
li 
11 
97 
88 
91 
60 
57 
80 
92 
85 
78 
“No rain” pred.. 
13 
7 
10 
9 
10 
18 
13 
80 
,, followed. 
7 
3 
9 
8 
7 
9 
8 - 
51 
Per cent, fulfilled. 
54 
43 
90 
89 
70 
50 
62 
64 
Total predictions, 
,, fulfilments. 
30 
29 
30 
30 
30 
30 
26 
205 
22 
23 
21 
20 
23 
20 
19 
148 
,, percentage. 
74 
79 
70 
67 
77 
67 
73 
72 
made from spectroscopic evidence alone, the barometer and ther- 
mometer were not consulted. In the ’ table “ no rain ” means that 
no rain whatever fell during' the twelve hours following the pre- 
diction. This, as explained when describing Table II., accounts 
for the apparently greater accuracy of “ rain ” than no rain ” pre- 
dictions. 
The success of a prediction has been judged of uniformly from 
the frequency, duration, and intensity of the showers which followed, 
and not. by the rainfall in inches. This was done because the situa- 
tion of 'the observing station (in the south side of Edinburgh) was 
unfavourable for the use of a rain-gauge; and as each prediction was 
made for a period of twelve- hours, the published rainfall for the 
