SOLAR HALO. 53 



Mr. Bliss is quoted as authority for the statement that 

 solar or lunar halos are not, as is commonly supposed, unfre- 

 quent or unusual in the Temperate Zone. The phenomenon 

 in most cases, however, consists of a single circle around the 

 luminary. Since 1890 the Philadelphia Weather Bureau has 

 observed and recorded 208 solar and 205 lunar halos, accord- 

 ino to Mr. M. B. Summers, first assistant of the Bureau. A 

 single halo was observed around the sun only a few days 

 before the one under discussion. Halos most frequently occur 

 during the Winter and early Spring months, the reason for 

 which is obvious. Such wonderful displays as were seen on 

 May 20th are extremely rare at points so far south in the 

 Temperate Zone, but are, as stated before, quite frequent and 

 brilliant beyond description in the northern latitudes, where 

 both explorers and scientists have made careful observations, 

 and have prepared long reports pertaining to them. 



Inquiry in manj- quarters and information obtained from 

 various sources in the vicinity of Philadelphia in regard to 

 the halos of May 20th developed considerable difference of 

 opinion as to the size, scope and the number of circles com- 

 posing the phenomenon, as well as to the position of the var- 

 ius halos and circles relative to the sun, also the relative posi- 

 tion of the circles, one to another. Many of these opinions 

 were held by persons whose views in the matter cannot be 

 taken into serious consideration, yet not a little difference of 

 opinion as to what was actually visible was expressed by pro- 

 fessional men who by reason of study and experience have 

 trained powers of observation. These men after viewing 

 the spectacle, more from a scientific standpoint than that of 

 simply an interested spectator, still disagree one with another. 

 The points of disagreement were on matters of detail, since 

 all the important features as described in this paper were not 

 questioned. Later on in this article an acceptable theory 

 will be advanced, which will attempt to assign reason- 

 able causes for the different details as observed by inter- 

 ested persons at various points in the vicinity. As viewed 



