THE MOON. 



intensity of sunlight and moonlight are considered. It may be 

 assumed, without sensible error, that the intensity of the sun's 

 light on the surface of the moon and on the earth is the same ; it 

 follows from this, that supposing no light whatever to be absorbed 

 by the moon, but the entire light of the sun to be reflected from 

 its surface undiminished, the intensity of moonlight at the earth 

 would bear to the intensity of sunlight the same proportion as the 

 magnitude of the moon bears to the magnitude of the entire 

 firmament, that is, the proportion very nearly of 1 to 300000 ; 

 but there is no reflecting surface, however perfect, which does not 

 absorb the light incident upon it in a very considerable degree, 

 and the rugged surface of the moon must be a most imperfect 

 reflector. It may then be considered as demonstrated that the 

 intensity of moonlight is much more than 300000 times more 

 feeble than that of sunlight. We shall not, then, be surprised at 

 the absence of its heating power. 



But if the rays of the moon be not warm, the vulgar impression 

 that they are cold is equally erroneous. We have seen that they 

 produce no effect either way on the thermometer. 



20. Curiosity will doubtless be awakened in a very lively 

 manner regarding the physical condition of our moon : what part 

 has the Maker of the solar system destined this body to play in 

 the economy of His creation ? Is it a globe teeming with life and 

 organisation like the earth ? Is that orb, which rolls in silent 

 majesty through the midnight firmament, the abode of life and 

 intelligence ? The beauty of her appearance naturally leads the 

 mind to conjectures of this kind. Yet the circumstances which 

 I have unfolded regarding the total absence of air and water 

 appear to exclude the possibility of any such supposition. How, 

 may it be asked, can it be conceived that a globe can have upon 

 it an organised world which is destitute of fluid matter in every 

 form ? How can growth, which implies gradual change, increase, 

 and diminution, and all the various effects in whicli fluidity is an 

 agent, go on there ? How can they proceed upon such a solid, 

 arid, unchangeable, crude mass ? Let it be remembered what a 

 multitude of purposes in our natural and social economy are sub- 

 served by the combination of the water and the atmosphere of our 

 globe. None of these purposes can be fulfilled upon the moon. 

 Perhaps, however, our notions on such questions may be cleared up 

 to some extent by a careful examination of the facts that scientific 

 research has collected respecting the physical condition of the 

 surface of our satellite. 



21. If, when the moon is a crescent, we examine with a tele- 

 scope, even of moderate power, the concave boundary which is 

 that part of the lunar surface where the enlightened hemisphere 



