J5!2 ON THE ELECTRIC COLUMN. 



cessively be seen in what manner these previous remarks on- 

 the electric Jlitid, and the experiments on the same suhject 

 contained in my former pa ler and the first parts of thi», are 

 connected with meteorology. 



Art. XI. I have said, that, as we ascend mountains, the 

 hi/grometcr, successively falling, indicates less and less eva- 

 Region of porated water in the air. We thus however attain the re- 

 clouds aud gion, in which clouds and rain are formed ; and there it is, 

 that the lessons of nature itself may guard us against the 

 arbitrary dictates of imagination : I shall therefore relate 

 what I have observed. At times when the atmosphere is so 

 clear, thai distant objects are seen very distinctly, and that 

 the hygrometer, according to the tables that Mr. de Saus* 

 sure and i have made from direct and separate experiments,- 

 does not indicate above two or three grains in each cubic 

 Formation of foot of that air — small clonds may be seen forming in all 

 '^^ *' parts of the very stratum of the atmosphere in which we; 



ftand, with very little or no wind. S metimes, without any 

 change in the temperature or moistttre of the intermediate 

 parts, these embryoes oi clouds dissipate: but at other times 

 they rapidly increase, unite together in the whole stratum) 

 in sight, aud announce to the observer, that soon he will be 

 enveloped by clouds. However, till the clouds, either moving 

 towards him, or forming around him, occupy the very spot 

 in which stand the liygrometer and the thermometer, he ob- 

 serves no sensible change in them : but the instant that a 

 cloud envelopes him, the hygrometer arrives at its point of 

 extreme moisture, and all the bodies are wet. 

 Rain, Art. XII. These preliminaries of rain ofteu remain along 



time, with only some variations, and at last dissipate with- 

 out effect; and as soon as the clouds disappear in one spot, 

 the hygrometer indicates the same dryness, as if no cloTid 

 had been there. But at last ; though without any percep- 

 tible difference in the preliminaries, because some other test 

 of the state of the air, beside those we possess, is wanting ; 

 the clouds increase in extent and thickness, above and belowr 

 the place of observation, and rain is produced in more or 

 less abundance. If rain be lasting, and at the same time 

 in a great extent of country, it may happen either in a calm 

 : , . , air, or during some regular wind. But when rain is partial 



8»4 



