270 LEAVES FROM THE BOOK OF NATURE. 



and shuts them off from the rest of the universe, towers 

 aloft to the amazing height of seventeen thousand feet ! 



If the number of these circular mountains is so great, 

 that of small, burnt-out craters is still more astounding; 

 even a moderately powerful telescope shows us some twen- 

 ty thousand. Inside they often sink to an incredible depth, 

 into which their walls cast a deep, everlasting shadow; 

 here there reigns entire gloom, which the light of the sun, 

 even at its highest, never reaches. Their tops, however, 

 when fully lighted up at the time of full moon, shine in 

 glorious splendor, reflecting the sun's rays with dazzling 

 lustre. Others show only their margin illuminated, like 

 a delicate ring of light, forming a magic circle around 

 the dark, yawning crater. Now and then we see two or 

 more strung together like rows of pearls, connected with 

 each other by canals, or even two at a time surrounded 

 by a common wall and combining their desolate horrors. 



Continued chains of mountains, like the Alps and Andes 

 of our mother earth, are rare in the moon, and even 

 when met with, only short and without spurs or valleys. 

 The longest ridge extends about four hundred and fifty 

 miles, but its peaks rise to the prodigious height of 

 seventeen thousand feet. On the other hand, the moon 

 abounds in countless, isolated cones, which in the nor- 

 thern half group themselves into long, broad belts. 

 Like the thorns of a chestnut, thousands of these moun- 

 tains rise suddenly from the plain, and are seen to 

 stretch their long, gaunt arms from the outline of the 

 moon's disc into the dark sky. Even the vast plains 

 of our little neighbor are covered with long, curiously- 



