French National iTi/Iitute. 1S9 



METEOROLOGT. 



On the Vunations of the State of the Heavens in the Mem 

 Latitudes betiveen the Equator arid the Pole, and the ef~ 

 fential Circumjlances by ivhicb they are accompanied. 



The influence of meteors on the refults of agriculture has 

 sendered it of importance at all times that the law of the fuc- 

 ceffion of thefe phenomena (liould be known ; and the great 

 advantages which would arife to mankind from the poffibility 

 of foretdling the natvn-e of the icafons, fufficiently juftifies all 

 the fruitlefs'^ttempts hitherto made to accomplifli that End. 



Being much ftruck with thefe advantages, C. Lamarck was 

 difcouraged by the bad fuccefs of thofe who had preceded him 

 m this career; and from continuing to purfue it with ardour, 

 after publifhing in ditferent works the caufes wliich he af- 

 ligns to the prevailing meteorological conflitutions, he has 

 given in a late memoir an examination of the variations of 

 the ftate of the heavens, that is to fay, of the atmofphere : he 

 refers this flate, 



I ft, To the influence of the fun's light : 

 3d, To that of the winds. 



But he is of opinion that in the temperate zones the in- 

 ^uence of the winds on the temperature of the ftrata of the 

 atmofphere is much (Ironger than that of the light of the 

 fun; and that there thence refult in the dcnfuy and heat of 

 thefe ftrata, which naturally become rarer and colder the 

 higher they go, inverfions to which he afcribcs the formation 

 of the clouds. 



The difcordance of the eflrefts which the fame wind pro- 

 duces at diiTerent times feemed to oppofe to the eftablifhment 

 of a theory of thefe efledls an infurmountable obftacle : but 

 from numerous obfervations C. Lamarck is of opinion, that 

 befides ihcdireftion and nature of the winds alone, attention 

 ought to be paid alfo to the height at v, hich they blow in the 

 atmofphere. 



Of the fa£ls collected by the author, and which he confi- 

 ders as iuQlcicntly proved, we fliall mention the following : 

 " When a iiorth-iuejl and ^foulh-cajl wind prevail fimultane- 

 oufly in two dilferent (trata of the atmofphere, if the fou'h- 

 tafl be the lower one, we may expe6l to fee the weather be- 

 come clear ; but if ihis wind be the higher, the contrary will 

 take place," 



XXXIV. Intel- 



