7 
FO 
52 M. W. Harrington— Weather making. 
the up-moving column of air which shall be formed over them may haye 
a wide base, and thus may ascend to a considerable height before it may 
be leaned out of the perpendicular by any wind which may exist at the 
time. 
Espy's theory was practically the modern convective theory of 
storms, and to this most worthy student of science is due the 
credit of calling effective attention to the part which the con- 
densation of aqueous vapor plays in the mechanism of storms. 
Third Method.—Another proposed method of making rain arti- 
ficially is that of L. Gathman, of Chicago, patented in 1891 
(number 462,795). His method is to “Suddenly chill the atmos- 
phere by rapid evaporation, and it is also advisable to produce 
a heavy concussion in connection with the cooling in order to 
set the different air-currents in motion. It is obvious that sud- 
den and rapid evaporation in the upper regions of the atmos- 
phere could be accomplished in various ways by the evapora- 
tion of various highly compressed gases; but the evaporation 
consequent upon the release of liquefied carbonic acid gas is 
thought to be the most efficient.” He proceeds: 
In accordance, therefore, with my invention, liquefied carbonic acid 
gas is liberated in the upper regions of the atmosphere and will, of course, 
instantly evaporate and spread out in a sheet of vapor of an extremely 
low temperature and produce a cloud. The surrounding atmosphere will 
be chilled by its proximity to the cold vapor and the moisture in the 
atmosphere will be condensed thereby. The condensation takes place in 
large quantities and with great rapidity, so that a cloud is formed that 
will precipitate a rainfall upon the earth. 
The liquefied carbonic acid gas can be confined in a suitable shell or 
casing, said casing also to contain an explosive—gunpowder, dynamite, 
etc—which is thrown or shot into the upper regions of the atmosphere 
and there exploded by a time-fuse. A balloon, moreover, could be em- 
ployed to elevate the shell or casing containing the liquefied carbonic 
acid gas, and the explosion to liberate the gas could be made by an elee- 
tric current controlled by persons upon the earth. 
Mr Gathman also published a little book in which were re- 
produced, with approval, Professor Newcombh’s article entitled, 
“Can We Make it Rain?” and Professor Houston’s “ Artificial 
Rain-making.” In this book we learn that Mr Gathman has 
been occupied with the use of condensed carbon anhydride to 
cool heavy guns, and was led to his theory by the results of his 
experiments with ordnance. He also experimented on his 
method of rain-making, and says (page 38) : 
> =" 
