OPTICS 



which are associated alike with sun and moon, are shown 

 in the figure. There is an additional vertical beam shown. 



After the lateral sun-dogs the commonest phenomenon 

 was this vertical beam of light, which rose from the sun 

 or moon, and passed beyond the ring, if one were present. 

 In the case of the sun the beam of light was yellow, that 

 from the moon was often decidedly red. It could not 

 readily be seen when the whole disc was in sight, but often 



Inverted Rings Rotjnd the Sun, February 7, 1909 



the yellow beam was seen rising from behind a hill, the 

 sun itself being entirely hidden. It could never be traced 

 below the sun or moon, and we have no notes of a hori- 

 zontal beam of the same kind. 



A complete halo round the sun or moon was usually 

 of uniform brightness, without brighter spots or straight 

 beams. 



On February 7, 1909, there were seen portions of 

 three rings, convex towards the sun. The one over the 



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