Gathman’s Plan. bo 
In making some experiments last year, a shell filled with liquefied car- 
bonie acid gas was exploded at a height of 600 feet; a cloud was produced 
in the clear sky at once, and, floating along on a current of air, was visible 
for miles. This experiment was made in July, 1890, and since that time 
I have made sufficient other experiments to satisfy myself that I can pro- 
duce rain whenever necessary, or at will. Experiments made in my 
astronomical observatory, at a height of only seventy-five feet, have 
provén that by the evaporation of liquefied carbonic acid gas a rain 
shower on a small scale can be produced with but a small quantity of the 
gas. When completed arrangements have been made, the experiments 
mentioned will be seen to be but a step to the practical illustration on a 
grand scale. 
It appears that in Gathman’s method the explosion plays a 
very subordinate part; but in the method to follow the explo- 
sion is the main, if not the only thing. 
Fourth Method.—The concussion theory is probably an old one, 
though it is not correct to refer it to Plutarch, as is sometimes 
done. In his life of Marius, referring to the battle with the 
Teutons near Aix, in July, 102 B. C., Plutarch says: “ Extra- 
ordinary rains pretty generally fall after great battles; whether 
it be that some divine power thus washes and cleanses the pol- 
luted earth with showers from above, or that moist and heavy 
evaporations steaming forth from the blood and corruption 
thicken the air, which naturally is subject to alteration from the 
smallest causes.”* Here are two distinct suggestions for rain- 
making, but not that of concussion. 
The first elaborate treatment of the concussion theory appears 
to have been by Edward Powers, civil engineer, who published 
in 1890 a book on the relations of battles to rainfall, The first 
edition was printed in Chicago in 1871, but most of the edition 
was destroyed by the great fire in that city, which also destroyed 
the stereotype plates. The latest issue seen by me contains an 
inset of 15 pages devoted to a criticism of Professor Newcomb’s 
article already mentioned. The aim of this book is to prove 
that great battles or heavy cannonading are usually soon fol- 
lowed by rainfall. A fair criticism of the book is that such 
phenomena are not invariably followed by rain. The coinci- 
dences could be explained by the fact that in the season of mili- 
*Plutarch’s Lives, Clough’s revision, Am. Book Exchange edition, 
1881, pp. 590-391. 
