National Geographic : 1894 Apr 25
The Author's Conclusions. rain ? A. Floating particles of spongy texture will absorb the moisture hygroscopically. If the air is dry this will make it drier and prevent rain. If the air is very moist and near satu ration, any solid particles in the air will facilitate the condensa tion; witness the experiments of Aitken and Barus. Thus, when other conditions are very favorable, an addition of much dust or smoke to the air might determine a fall of rain. Q. Will the expansion of carbon anhydride produce rain? A. Mr Gathman says he has tried it and with success. Experi ments should be made systematically. Q. Will electric connection with a cloud aid in rain forma tion? A. M Baudouin says it does. Q. Will a conflagration produce rain? A. Quite probably, under favorable circumstances. It acts in the line in which nature acts, according to the best of our knowledge. Condensation is the result of chilling the air. The theory of chilling by mixture, the Huttonian theory, a century old, is now known to be ineffi cient. The chilling in nature seems to be due either to the ascent of air and its consequent expansion and loss of heat or the chill ing of one cloud by having the shadow of a higher cloud fall on it in sunlight. The chilling by ascent is the method evoked in the Espy plan and appears to be by all odds the most effective rain-producer in nature. Q. If rain can be nade, how much will it cost? A. This is truly an American question, and quite appropriate to the fin-de-siecle. Mr Powers, who, by the way, says that Mr Dyren forth did not after all really try his experiment, puts the cost of one experiment with government aid at $80,000. Gathman says he can sprinkle the earth at a cost of from $30 to $90 a square mile. Espy proposed to fire the low forest growths at regular intervals at a cost less than five mills per citizen per year. The method of concussion costs the comfort and peace of all within hearing, a cost which a much more certain result would not justify. 9-NAT. GEOG. MAG., VOL. VI, 1894.
1894 May 23
1894 Mar 17