358 SPECIAL EESULTS IN THE UllANOLOGICAL 



entire absence of any diffused light must cause the heavenly 

 bodies, as seen from thence, to appear projected against a sky 

 almost black in the daytime ( 576 ). No undulation of air can 

 there convey sound, song, or speech. The Moon, to our ima- 

 gination which loves to soar into regions inaccessible to full 

 research, is a desert where silence reigns unbroken. 



The phenomenon which is sometimes remarked in occul- 

 tations of stars by the Moon, of a pausing or " cleaving" of 

 the star to the Moon's limb or margin ( 577 ), cannot well be 

 regarded as a consequence of the " irradiation," which, from 

 the great difference in the intensity of their light, causes the 

 part of the Moon illuminated directly by the Sun, when 

 only a narrow bow, to appear to the eye as if it encom- 

 passed the remaining dark portion. In a total lunar eclipse 

 Arago saw most distinctly a star cleave during the con- 

 junction to the dimly-illuminated red disk of the Moon. 

 Whether the phenomenon here alluded to is to be regarded 

 as the effect of physiological causes ( 578 ), or of aberra- 

 tion arising from the refrangibility and sphericity of the 

 eye (579)^ i s s till a subject of discussion between Arago 

 and Plateau. The cases in which it is affirmed that in an 

 occultation a disappearance and a reappearance, and then 

 again a disappearance, have been seen, may very well indi- 

 cate an outline of the moon accidentally deformed by moun- 

 tain precipices and deep chasms. 



The great differences visible in the reflected light in dif- 

 ferent parts of the illuminated lunar disk, and especially the 

 irregularity of the line which separates the illuminated from 

 the unilluminated portion of the disk in phases intermediate 

 between new and full moon, gave occasion in very early 

 times to the formation of intelligent views respecting 



