PHOTOGRAPHY OF THE LUNAR SURFACE. 121 



not only in the polar regions, hardly touched by the grazing rays of the 

 sun, but even in the equatorial regions. Deprived of the protecting 

 mantle formed by the air and the water vapor, it is subjected to the same 

 conditions, in a more aggravated form, as the highest terrestrial moun- 

 tains, the most extreme dryness, intense nocturnal radiation, and a very 

 low mean temperature. One can hardly imagine an abode more unfa- 

 vorable for the existence of human life, and as even the most rudimen- 

 tary forms are absent on the earth at great altitudes, it is impossible to 

 conceive of any which could adapt themselves to the moon in its present 

 state. 



The same conclusion seems valid, however deeply the question be 

 considered. 



Without doubt the elements of our terrestrial atmosphere have 

 existed on our satellite. Water in the form of vapor has exerted a 

 most energetic action, and has formed a relief more marked, on the 

 whole, than that of the earth. The atmosphere must, however, have 

 been quite rare when the surface temperature reached the condensation 

 point, and must have been almost entirely absent when it reached the 

 freezing point. The conditions of humidity and temperature required 

 for the development of terrestrial organisms are therefore never found 

 together on the moon. Its history has many features in common with 

 the primitive evolution of the earth, though none, it appears, in com- 

 mon with the contemporaneous period. The moon seems like a planet 

 of which the development has been prematurely arrested, fixed in its 

 final form, to become a mute spectator of our own agitations. 



Should we for this reason forsake the study of that sterile globe as 

 being without interest"? We should regard the question from a broader 

 standpoint. The period when life flourishes is but a chapter in the 

 history of a celestial body, although without doubt the most interesting 

 one, but we can not consider it only at its best without extending our 

 researches still further. Physical and chemical laws develop their con- 

 sequences within the widest limits of time, and we find in the series of 

 transformations of a planet a subject having an almost equal philo- 

 sophical importance. The photographic observation of our satellite is, 

 from this point of view, full of promise. 



Although incapable of sustaining organized life, the moon will never- 

 theless continue to exert a permanent action in the development of the 

 human mind. By the study of the important phenomena which are 

 connected with its attraction for the earth, it has given rise to the 

 highest efforts of mathematical genius. It aids us in conceiving a 

 more just and disinterested view of the universe as a whole. It makes 

 us reach out in thought, not only from ourselves, but from the earth 

 where we abide, and from the short lifetime in which all our experiences 

 are embraced. 



