The Moon. 



time that she makes her periodical revolution 

 round the earth*. On this account she always 

 presents to our view the same part of her surface, 

 or nearly the same face. There may, however, 

 be observed a little variation in the situation of 

 her spots, or in the position of her face ingeneraJ, 

 as presented to the spectator. This is called a 

 Vibration, and depends on the different aspects 

 which the moon assumes in consequence of the 

 diurnal motion of the earth on its axis, and of 

 the inclination of the axis of the moon in de- 

 scribing her elliptical orbit. 



In the course of a year the moon makes 13 

 and revolutions upon her axis ; and as in eacli 

 of these revolutions the sun enlightens suc- 

 cessively every part of her surface, it follows 

 that the inhabitants of the moon, if there be 

 any, would enjoy about 13 days and a third. 



The phenomenon of the harvest moon is not 

 generally understood. I shall endeavour to 

 explain it, following chiefly Mr. Ferguson, and 

 deviating but little from the simple language of 

 that justly popular philosopher. 



It has already been stated that the moon rises 

 about 49 minutes later every day than on the 

 preceding; but this is strictly true only with 

 regard to places on the equator. In places of 

 considerable latitude there is a remarkable dif- 



* The inhabitants of the moon, therefore, if we suppose 

 there are any, would have but one day and one night in 

 the course of a month. 



