40 



CELESTIAL, ATMOSPHERIC, AND 



ecliptic 23° 28'. Clearly, therefore, a secondary rainbow, 

 and still less a primary rainbow, would not be visible about ,j 

 midday. At the autumnal equinox (Sept. 21st) it is evident 



FIG. I. 



K^ Sun at 

 / middav June2 



Sun at 



rr\\dday 



Sept. 21 



Sun at 

 any date 

 bn the horizon 



'-Dark blue 

 '-Greenish-Fellow 

 ' — Light red 



Dark blue 

 •- Greenish -yellow 

 ' — Light red 



that, at midday, the altitude of the Sun at Athens is 52°, 

 and some part of a secondary rainbow might be seen, even 

 at midday, and part also of a primary rainbow could be seen 

 at midday, during the shorter days of the year. It will be 



