450 Eclipse of the Moon. 



from a great proportion of the blue rays of the light which 

 passed through the lower regions of the atmosphere, being 

 refracted farther inwards in the cone of the earth's shadow, 

 or bent down on the earth'3 surface. The penumbra, how- 

 ever, had a purple tint, which seems to be an effect due 

 chieflv to the higher regions of the atmosphere ; the blue re- 

 fracted by a. higher and rarer stratum, being intermingled 

 with the red, refracted by a lower and denser one. 



Different portions of the moon's surface continued to shine 

 during the eclipse with different degrees of brilliancy, as observ- 

 ed in the obscure part of the new moon. The portions most 

 highly i'luminated, were disposed as a ring round the disc, but 

 appeared in greatest breadth towards the poles of the moon, 

 and narrowest towards the western side. The North Pole was 

 the most illuminated, and at the upper or southern limb, the 

 greatest light seemed to come from a point to the eastward 

 o't the pole ; nothing appeared to determine decisively whether 

 this difference arose partly from light emitted by the moon it- 

 self, or altogether from more copious reflection by different 

 parts of its surface. If water existed in a state of fluidity in 

 the moon, we should see its poles more brilliant, from accumu- 

 lations of snow there. The atmosphere of the moon is so 

 rare and shallow, that astronomers doubt whether a slight 

 indecision .some times observed in the sinking of stars behind 

 it, ought to be ascribed to that or to some other cause ; the 

 warmest parts of its surface must be in the condition of the 

 tops of o r loftiest mountains, and the temperature of its 

 elevations is probably little above that of the planetary space. 



If water therefore abound there as on the earth, it cannot 

 be fluid, but must rest almost every where as a covering of 

 changeless snow; and if we conceive it somewhat less abun- 

 dant, or more in the state of ice in the depressions of the 

 moon's surface, the hypothesis will explain all the appear- 

 ances of the disc. 



During the greatest obscurity in the late eclipse, the moon 

 was still beautifully distinct, and might have been supposed 

 only under a slight discoloring haze. When the edge of the 

 disc attained again its full illumination, there was in some 

 degree the same appearance of projecting, as we see in the 

 brilliant part of the new moon, compared with the obscured 

 part which it grasps. The shaded part at the same time, ap- 

 peared to assume a deeper tint. The effect of a brilliant ob- 

 ject in obscuring a gloomier one beside it, may be readily 

 seen in the new moon, when nearly half-full. The unillumi- 

 nated part will then be scarcely observable, but if we place 

 ourselves so that an object at some distance from the eye, 

 obscure the enlightened part, then may we observe the other, 

 hitherto obscure, start into view in gratifying brilliancy and 

 distinctness. J. A. 



