THE MOON. 501 



virtue of the attractive force which she exercises in common 

 with the Sun, excites motion in our ocean the liquid portion 

 of the Earth gradually changes the surface by periodical 

 floods, and the outlines of continental coasts, by the destruc- 

 tive agency of the tides, hinders or favours the labour of 

 men; affords the greater part of the material from which 

 sandstones and conglomerates are formed, and \vhich are 

 again covered by the rounded, loose transported detritus. 51 

 Thus the Moon, as one of the sources of motion, continues to 

 act upon the geognostic relations of our planet. The indis- 

 putable 81 influence of the satellite upon atmospheric pressure, 



that of the Sun." Liouville finds, on the contrary: " Que, 

 si la Lune avait oceupe a 1'origine la position particuliere 

 que 1'illustre auteur de la Mecanique Celeste lui assigne, 

 elle n'aurait pu s'y maintenir que pendant un terns tres 

 court." " That if the Moon had occupied at the beginning 

 the particular position assigned to her by the illustrious 

 author of the Mecanique Celeste, she would not have been 

 able to maintain it for more than a very short time." 



61 On the Transporting Power of the Tides, see Sir Henry 

 de la Beche, Geological Manual, 1833, p. 111. 



c Arago, Sur la question de savoir si la Lune exerce sur 

 notre Atmosphere une influence appreciable, in the Annuaire for 

 1833, pp. 157-206. The principal advocates of this opinion 

 are Scheibler ( Untersuch. uber Einjluss des Mondes auf die 

 Verdnderungen in unserer Atmosphdre, 1830, p. 20) ; 

 Flangergues (Zwanziyjahrige Beobachtungen in Viviers, Bibl. 

 Universelle* Sciences et Arts, torn. xl. 1829, pp. 265-283, and 

 in Kastner's Archiv f. die ges. Naturlehre, Bd. xvii. 1829, 

 sees. 32-50) : and Eisenlohr (Poggend. Annalen der Physik, 

 Bd. xxxv. 1835, pp. 141-160, and 309-329). Sir John 

 Herschel considers it very probable that a very high tem- 

 perature prevails upon the Moon (far above the boiling-point; 

 of water), as the surface is uninterruptedly exposed for four- 

 teen days to the full action of the Sun. Therefore, in the 

 opposition, or some few days after, the Moon must be. in 

 some small degree, a source of heat for the Earth ; but tins 



r 2 



