f>84 Fiench National Institvte. 



sisting more the tfftct of the liealed steam, does not require 



to be so thick*. 



Almost the whole of meteorol(;gv depends on the Tp.riable 

 action of heat upon the atmosphi-'ie. It i? the air, when va- 

 riously heated, that produces vhc winds, by the inequality of 

 its dilatations ; and the winds, carrying *hfi vapours into 

 warmer or colder places than those where they were formed, 

 cause their more complete solution, or their precipitation 

 more or less rapid, i. e. fine weather or rain. 



M. Dupont Nemours, member of the class cf history, 

 has presented to the class of sciences some reflections, 

 which have the merit oJ- rendering in some measure sensi- 

 ble, the futility of every attempt to predict these phsenomeaa 

 from the analogy <ind experience of the past. 



The zone, in the diflerent points of which the sun is ver- 

 tical in the course of the year, is never precisely the same 

 upon the earth for two consecutive years, nor even for an 

 Jn^^n;tv of centuries : in the mean'time the precession of the 

 equinoxes, which does not collect t'lem at the same points 

 until after more than 26,000 years, and the variations of the 

 obliquity of the ecliptic, of which the period is still more 

 tardy, contribute to vary this zone : and even supposing 

 that we had one day of observations antient enough, — in order 

 to be applicable, it must have been requisite that the surface 

 of the earth, the seas, and mountains, which are not less es- 

 sential elements of this phsenonienon, had not changed in 

 this whole interval. 



]M. Dupont admits that electricity contributes also to vary 

 the weather, forming >\ater by the combustion of hydrogen 

 gas. It is true that it seems now clearly ascertained, that 

 this jras does not exist in tiie region where storms are 

 formed : but M. Dupont supposes that it is brought down 

 from hia;her regions in tempests, which, by their violence, 

 dis'^ irb the natural order qf the strata of the almospliere, 



• The application of lii'ocs to boilers dees not appcr.r to have been an invpn- 

 jionoi count Humford's. i-ateiits were taken out in England for such a con- 

 struction of boiler? scvtr,.l years ago. A patent was likewise taken out 

 jome venrs ago for hcatir.j; w.'.tcr bv paf>i;ig steam into i;. E.ht. 



XLIII. lUr 



