358 



THE ILrjrMTNATION OF THE ECLIPSED MOON. 



tho rofloctod sunligLt, only becoming porceptiblo when llio 

 illumination is much reduced, as in a total eclipse, or as 

 in tho crescent moon, when tho shady portion of the disc, 

 feebly illuminated by earth-light, assumes a tint not very 

 unlike that of the eclipsed moon. 



The views I have thus referred to are, however, chiefly 

 of interest as leading up to the conclusion that the varying 

 light of the moon in eclipse is to bo explained by tho vary- 

 ing condition of t,ho atmospheric ring through which the 

 sun's rays pass to roach tho moon. The objections to this 

 view, supported though it has been by the highest astro- 

 nomical authorities, are to my mind insuperable. The 

 particular modification of it which seems at present to be 

 generally accepted, is especially open to criticism. 



In an article in tho Times, published on occasion of the 

 eclipse of October, 1884, tho writer explains the matter 

 in these words : — 



" If tho part of the terrestrial atmosphere through which 

 the solar rays pass be tolerably free from vapour, the red 

 rays are almost entirely al)sorbod, leaving the blue rays, 

 which give too feeble an illumination to render tho moon 

 visible ; while, on the other liand, if tho atmosphere bo 

 highly saturated, the blue rays are more effectually ab- 

 sorbed, and the red rays transmitted to the moon, thus 

 rendering it visible." 



According to this view, then, it is a saturated condition 

 of the air which, transmitting specially tho red rays, 

 favours tho illumination of the moon; while a dry atmos- 

 phere, absorbing the red rays, reduces illumination. But 

 this, I submit, is exactly contrary to what wo habitually 

 observe. When the sun sots with a red disc, its light, 

 instead of being increased, is so much reduced that wo 

 can gaze on it without discomfort. The same thing occurs 



