18 



NATURE FOR ITS OWN SAKE 



Thetodi- 

 acal light. 



Jfoonrfce, 



first twilight is, however, sometimes followed 

 by a second glow ; and after this has passed 

 there is occasionally another light seen in the 

 western sky called the zodiacal light. This 

 usually forms itself in the shape of a pyramid, 

 with its base toward the horizon and its apex 

 extending zenithward along the track the sun 

 has traversed. It is a pale nebulous light, like 

 that of the star clusters called the Milky Way ; 

 it appears more frequently in the tropics than 

 in the temperate zones, at dawn as well as at 

 twilight, and is often referred to as the " False 

 Dawn" and the " Wolfs Tail." The cause of 

 its appearance has not yet been satisfactorily 

 explained. 



No sooner is the sun gone (at times before it 

 is gone) than the moon comes up beyond the 

 eastern hills, at first rising slowly and then sud- 

 denly bursting into view. If the day has been hot 

 and dry the face of the disk is red or deep or- 

 ange, abnormally large in appearance, and often 

 bulged and misshapen as regards its circle. We 

 are looking at it through that same lower stratum 

 of dense air which has been rising all day from 

 the earth, and is still rising though the sun has 

 set. It is the dense air that gives the abnormal 

 size and the ruddy color. As the orb rises 



