WEATHER MAKING, ANCIENT AND MODERN. 263 



effective attention to the part wliich the condensation of aqueous vapor 

 plays in tlie niecliauism of storms. 



Third method. — Another i)roposed method of making rain artificially 

 is that of L. Gathman, of Chicago, patented in 1891 (No. 462795). His 

 method is to '^ suddenly chill the atmosphere 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 sudden and rapid evaporation in the upper regions of 

 the atmosphere could be accomplished in various ways by the evapora- 

 tion of various highly compressed gases; but the evaporation conse- 

 quent 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 condensa- 

 tion 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, dyna- 

 mite, etc. — which is thrown or shot into the upper regions of the atmos- 

 phere and there exploded by a time fuse. A balloon, moreover, could 

 be employed to elevate the shell or casing containing the liquefied 

 carbonic acid gas, and the explosion to liberate the gas could be made 

 by an electric current controlled by persons upon the earth." 



Mr. Gathman also published a little book in which were reproduced, 

 witli approval. Professor Newcomb'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 Avith the use of con- 

 densed carbon anhydride to cool heavy guns, and was led to his theory 

 by the results of his experiments with ordnance. He also exi)erimented 

 on his method of rain making, and says (p. 38) : 



"In making some experiments last year, a shell filled with liquefied 

 carbonic acid gas was exploded at a height of 000 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 produce rain whenever necessary, or at will. Exper- 

 iments made in my astronomical observatory, at a height of only 75 

 feet, have proven that by the evaporation of liquefied carbonic acid gas 

 a rain shower on a small scale can be produced with but a small quan- 

 tity 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 Gathmau's method the explosion plays a very sub- 

 ordinate part; but in the method to follow the explosion 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. 



