Concerning ike Injlieenee of the Motn upon the Atmofpkere of the Earth ■ 489 



moon pafles through the fix northern figns of the zodiac, and I call the other the auflral 

 conftitution, becaufe the moon pafles through the fix foutheru figns, during this 

 period. 



I am convinced by obfervation, that during a boreal conftitution, the winds which chiefly 

 prevail in this climate blow from the fouth, fouth-weft, and from the weft. Sometimes in 

 fummer they pafs to the fouth-eaft. In general the barometer during this conftitution, 

 . prefents but moderate elevations in the column of Mercury. The weather is ufually rainy 

 or damp, and the air is loaded with numerous clouds. And laftly, it is particularly du- 

 ring this conftitution that we obferve the efFefts of ftorms and tempefts, when the caufes 

 which occafion them become a£bive 



On the contrary, during an auftral conftitution, the winds which chiefly predominate^ 

 blow from the north and north- weft, and in fummer north-eaft, and even'eafterly winds. 

 In general during this conftitution, the barometer exhibits confiderable elevations In the 

 column of Mercury, at leaft if the wind is not very ftrong ; the weather is then moft 

 ufually clear, cold and dry, and in the fummer it is feldom (I might almoft fay never) 

 during this conftitution that ftorms arc formed. 



Thefe two atmofpheric conftitutions are not however fo permanently charafterifed as to 

 render it eafy to diftinguifli them at all times by the ftate of the atmofphere. The atmo- 

 fpheric air is fo moveable a fluid, and fo eafily difplaced, that it is not furprifing that nx 

 the temperate zones where the influence of the heavenly bodies a£ts lefs ftrongly, than be- 

 tween the tropics from various caufes, that they counteract very often the regular influ- 

 ence of the moon, and tend to maflc and even change its efi'efts*. 



The perturbations which thefe variable caufes produce on the regular efl"edts of the in- 

 fluence of the moon on the atmofphere, occafion in faft many variations in the two atmo- 

 fpheric conftitutions I have been defcribing ; and this is doubtlefs the reafon why they have 

 been hitherto difregarded. But 1 can pofitively aflert, that thefe perturbations, though 

 frequent, and fometimes very confi^derable, do not prevent the character of each of thefe 

 conftitutions from being remarked in the greateft number of cafes. 



The probability that I have found is, according to my obfervations, eftimated as 5 out 

 of 8 ; that is to fay, out of 48 atmofpheric conftitutions comprehended in the lunar year, 

 I eftimate there will be found at leaft 30 agreeing with the principles pointed out in this 

 memoir ; and I muft add, that among the difturbing caufes which modify the before- 

 mentioned effefts, feveral may be forefeen, and perhaps even appreciated as to their 

 quantity of effift. 



It is not an opinion that I here offer, it is a fa£l I announce ; — ^an order of things that I 

 point out, and that any one may verify by obfervation. It appears to me to be altogether 

 unneccflary to give a detail in this place, of all the reafons which might be adduced to 

 prove the great utility of this knowledge. 



LAMARK. 



• To avoid lengthtning this extraft, I pafs over in filence the enumeration and developejnent of fuch of 

 the variable caufes as I have afcertained. 



Diredions 



