374 French National Institute, 



not be obtained unless three means, which he points out, 

 are employed in conjunction : of these means we shall men- 

 tion that only which consists in the establishment of a regu- 

 lar correspondence of observations made every day in differ- 

 ent parts of an extensive country, in order to ascertain 

 whether the great atmospheric variations observed in any 

 one place are really the result of any cause which has a 

 determinable periodical return. This means, says Lamarck, 

 is so essential that it is astonishing it should have been hither- 

 to neglected. 



After laying down these bases, Lamarck gives an account 

 of the results he has been able to obtain : he distinguishes 

 them into the knowledge of facts which cannot be doubted, 

 and simple observations. The alternate elevation or depres- 

 sion of the moon, above or below the equator, in the course 

 of each lunar month, produces in the atmosphere, according 

 to this author, very apparent effects. During the austral 

 declination of the moon, and particularly on the approach of 

 the austral lunistice, the winds which then prevail blow 

 from the regions of the north, north-west, or north-east, or 

 east, or from some of the points comprehended between these 

 points. The constitution of the atmosphere thence resulting 

 tends to give dry or cold weather, according to the season, 

 and to restore a bright atmosphere^and fine weather. During 

 the boreal declination of the moon, and particularly the ap- 

 proach of the boreal lunistice, the prevailing winds blow 

 from some of the points opposite to those mentioned above 

 as predominant during the austral declination. The atmo- 

 spheric constitution thence resulting tends to give cloudy 

 weather, more or less damp and rainy. It is favourable to the 

 formation of storms, which never take place but during this 

 declination of the moon. 



Among the signs which Lamarck considers as simple ob- 

 servations I shall mention only the following, and shall em- 

 ploy the same expressions as the author. 



''As the position of the lunar points changes very slowly, 

 which makes them fall for several months successively, some- 

 times on the lunisticial days and sometimes on the mean days, 

 this position gives rise to that stationary state of the atmosphere 



which 



