SOLAR HALO. 57 



southwesterly side of the line was quite faint and would have 

 been unnoticed by one making only casual observation. This 

 ring was also white, and of the same size as its "twin." 

 Both the last described circles' were due to the reflection of 

 light rays from faces of the many and varied shaped cr\-stals 

 existing at that time. 



In Philadelphia both the small and large halos were 

 observed by several persons to be complete rings : we are led 

 to believe, however, that the parhelic circle was confused 

 with and mistaken for the outer halo, but as the statements 

 are ver}- positive the point will not be disputed nor contra- 

 dicted. The circles that were tangential to the inner halo 

 were not generally noticed in the city. Often only parts or 

 arcs of the later mentioned circles are visible in displays of 

 solar halos, and appear as elliptical arcs, and may be noticed 

 at any point on the small halo and always tangent to it. 

 These arcs are known as the Arcs of Lowitz, having first 

 been discovered and described by the eminent scholar and 

 scientist, Johanon Tobias Lowitz. A careful search of vari- 

 ous records and papers treating on this subject fails to find a 

 description of these arcs appearing as complete circles as they 

 did during the display on May 20th. There can be no doubt, 

 however, that these circles in the recent phenomenon were, in 

 fact, the same features, and were caused by the same or sim- 

 ilar conditions as the arcs described many N^ears ago by Dr.' 

 Lowitz. 



The phenomenon being described was not so complete in 

 detail as displays of this kind usually are in the higher lati- 

 tudes, in that several of the interesting features generally 

 observed were missing. Images known as parhelia, and some- 

 times known as mock suns, are not unfrequently seen at the 

 intersections of the inner halo and the parhelic circle. These 

 images did not appear, or if they were present were too dim 

 to attract attention. Other images similar to the parhelia, 

 and known as parayithellia , are often visible at the intersec- 

 tion points of the outer halo and the parhelic circle. The 



