392 
these figures were entirely taken from pluvio- 
graphs, it is possible to refer the amounts of 
rainfall exactly to the prescribed test period. In 
Figures 3 and 4, the results from this source 
have been assembled. It is extremely surprising 
to find that, for a majority of the recording 
stations south of the Po, the mean daily rain- 
fall is again approximately doubled for the 
seeded days by comparison with the unseeded 
days during the test year 1957. This phenome- 
non was significantly not repeated in 1958. From 
Figures 2 and 4 it can be seen that in 1958 it 
is possible only to establish a doubling in the 
mean rainfall as due perhaps to seeding in the 
northern half of the Tessin. Yet at the same 
=o — 
Reckingen 
Cevio? 
2° 
Fic. 5—Kolmogorov-Smirnov 
RAYMUND SANGER 
time even in the southern half the question of 
the mean rainfall between the seeded and the 
unseeded days is still considerably above unity. 
However, in the case of the Italian recording 
stations it does show a considerable fluctuation 
around unity. 
That the recorded 100% increase in the 
amount of precipitation on seeded days even 
(in 1957) at the Italian recording stations south 
of the Po should have been brought about by 
the AgI seeding, is a physical impossibility; the 
observation can be explained in no other way 
than as the result of statistical scatter. And in- 
deed these recording stations show a relatively 
small number of days on which there was any 
er, 
1 \= 
2 Disentis 
Bellinzonm™ 
test applied to the daily precipitation 
quantity of the test region, 1957 and 1958; percentage probability P of an 
error of the first type 
