Non-existence in the Moon of Clouds^ Seas^ ^c. 53 



out all their extent. Nor is there the slightest ground for be- 

 lieving there is any system of rivers at all analogous to ours. 



The forms of the lunar mountains perfectly agree with this 

 conclusion. Convex slopes (convexe boschungsformen), and 

 escarpments, far more remarkable than those of the earth, pre- 

 dominate in the moon. Slopes at an angle of 45° and even more, 

 are there the most common ; and not only the bright parts of 

 the surface, but also the seas, are covered with great rocky 

 masses. As the density of the material of which the moon is 

 formed is scarcely above the half of that of the earth (0.57), 

 we cannot easily admit that a greater number of compact 

 masses of rocks can be found on the moon than on the earth ; 

 and these masses could not be in a state habitually to resist 

 the action of water and of the atmosphere, and to maintain 

 themselves in a position so steep and perpendicular. Great an- 

 nular mountains are seen, with a regularity of form both on 

 their internal and external surface, which they could never pre- 

 serve on the earth, exposed, as they would be, to the influences 

 of air and water ; and this shews that they have been exposed 

 to no such influences, since the time of their formation. Val- 

 leys, except, of course, craters, are comparatively exceedingly 

 rare in the moon ; and all their relations are perfectly different 

 from those we find upon our globe; in fact, there are no 

 broad and long ones, through which rivers might flow. The 

 formation of regions in successive terraces is also wholly want- 

 ing in the moon. The declivity of the high mountains is as 

 rapid as that of a wall, and does not terminate in a valley, but 



we must succeed in obtaining instruments which will magnify, in linear size, 

 51,000 times, before we can hope to discover objects of that magnitude in the 

 moon. But, up to the present time, they add, the magnifying to 300 times 

 is the utmost extent we have succeeded in making any observations upon the 

 moon, whose results can be compared with each other. There is required, 

 therefore, a farther improvement upon our astronomical instruments, which 

 shall be to our present in the ratio of 510 to 3, or of 170 to 1. It is also ne- 

 cessary to suppose that the terrestrial atmosphere should become 170 times 

 more transparent; and that the inconvenience arising from the apparent 

 diurnal movement of the moon rendered 170 times more rapid, should be re- 

 moved, before we can ever hope to perceive from the earth, the living beings 

 who may possibly inhabit that heavenly body, which, compared with others, 

 is situated in our own immediate vicinity. 



