Eclipse of the Moon. -i !•' 



obscured, the moon may he entirely darkened. The earth, as 

 seen from it, will in these, and indeed, in all circumstances, pre- 

 sent wonderous and interesting phenomena; reserved, how- 

 ever, for hut one half of the Lunar orh. To every point oi 

 that face of the moon which constantly looks upon us, the 

 earth retains a fixed position, having all other bodies, during 

 the moon's month-long days and nights, rising culminating or 

 setting beyond it, and in every spot enjoying the glorious 

 vision, affords the finest and readiest opportunities of ascer- 

 taining relative positions and distances. It marks the same 

 periods as the moon does to us, by its increasing and waning 

 through the Lunar varieties of aspect; and with our oceans 

 and continents, flitting across in rapid succession; or the 

 points and ridges of our snowy mountains, glowing like spots 

 ■>{ flame above the dullness or commotion of our atmosphere, 

 it presents a ready and splendid chronometer, sub-dividing 

 into our days the moon's long intervals of light and darkness. 

 When the great orb is hidden in the sun's beams, and ad- 

 vancing to cover his disc in the Lunar eclipse, it will seem, 

 for a little, to push the sun's limb before it ; till, shortly, the 

 sun's disc will appear to extend round the earth's orb, and 

 embrace it with a ring of light, which will continue to diminish 

 on one side, and increase on the other, till they be again dis- 

 joined. 



But, besides the refractive power causing these appearances, 

 the earth's atmosphere possesses also a considerable disper- 

 sive power ; in virtue of which, the rays passing through 

 it are separated into portions of different colors, which are 

 transmitted in different proportions to the different parts of 

 the earth's shadow. This dispersion produces the blue of the 

 zenith, and the reddened atmosphere round the sun on the 

 horizon. A beautiful example of it is presented to us in this 

 climate at our sun-set ; which may, perhaps, afford the means 

 of comparing its influence in this respect with that of other 

 bodies. If we turn from the setting sun and look to the 

 eastern horizon, we shall observe along the tops of the moun- 

 tains a long arc of dull purplish red ; which, as the sun 

 descends, rises toward the zenith, followed by a border of 

 pale bluish green : these, when most distinct, have a breadth 

 of about six degrees ; and, as they ascend, fade, and become 

 indistinguishable. They appear to be a sort of spectrum pro- 

 duced by the structure and lenticular shape of the portion 

 of the atmosphere traversed by the sun's rays, which are 

 reflected back to us in their separated state by the parti- 

 cles of the eastern atmosphere; the dispersed light being 

 intermingled with the ordinary blue of the sky. A similar 

 effect was observable in the eclipse. During the giea'rst 

 obscuration, the moon had a fiery brassy hue, which 



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