A NEW CRATER IN THE MOON. 101 



volcano to which Dr. Klein has recently called the attention 

 of astronomers, it may be well briefly to describe the con- 

 dition of the moon's surface. 



This surface, which is equal in exttfnc fp t about that; ttfj 

 the American Continent, or to Europe', and^Africa together 

 (without their islands), is divided intO j two chi^f; porticjrjs-^ - 

 the higher levels, which are in the rfiairv tff lighter thit, a'nd 

 the lower levels, which are, almost without exception, dark. 

 It may be remarked in passing that very erroneous ideas 

 are commonly entertained respecting the moon's general 

 colour. The moon is very far from being white, as many 

 suppose. On the contrary, she is far more nearly black 

 than white. It has been well remarked by Tyndall that if 

 the moon were covered with black velvet (14,600,000 square 

 miles of that material would be required for the purpose), 

 she would still appear white to us, for we should see her 

 disc projected on the blackness of star-strewn space. The 

 actual tint of the moon as a whole is nearly the same as 

 that of gray weathered sandstone. The brightest parts, 

 however, are much whiter ; Zollner infers from his photo- 

 metric experiments that they can be compared with the 

 whitest of terrestrial substances. On the other hand, the 

 darkest parts of the moon are probably far darker than 

 porphyry, even if they are not so dark that on earth we 

 should call them black. The fact that the low-lying parts 

 of the moon are much darker than the higher regions is full 

 of meaning, though hitherto its significance does not seem 

 to have been much noticed. Either we must assume that 

 these lower regions, the so-called seas (certainly now dry), 

 are old sea bottoms, and owe their darkness to the quality 

 of the matter deposited there in remote ages, or else we 

 must suppose that the matter which last remained 

 fluid when the moon's surface was consolidating was of 

 darker material than the rest. For such matter would 

 occupy the lowest lunar regions. There is here room for a 

 very profitable study of the moon's aspect by geologists. 

 I doubt not that, however different the general past 



