Halos. 299 



which puts the matter entirely beyond dispute. While Commodore 

 Hardy was lying off Boston, during the late war, his whole ship's 

 crew observed, during a particular state of the atmosphere, the figure 

 of a man, resembling a sailor of a colossal size reflected in the 

 heavens. 



If the particles of the atmosphere had reflected each its respec- 

 tive image, the object would have been confused, shapeless and 

 obscure. 



The halo being thus accounted for, the anthelia, or mock suns 

 yet remain to be explained. As yet nothing of this kind has been 

 attempted. The best works, within our reach, are silent on the sub- 

 ject, but yet it is evident that at the particular points, where they are 

 seen, a greater collection, and a greater reflection of homogeneous 

 rays must take place than at any other. 



The idea most obvious is this, that those direct rays of the sun, 

 which would otherwise have passed off uncollected, are attracted to 

 the edges of the cloud, drawn within its influence, and then refracted 

 and reflected to the eye of the spectator. 



2. hvNAR.— West Point, March 27, 18SI. 



In observing a beautiful halo around the moon, on the night of the 

 20th inst., I was led to consider the cause of this remarkable phe- 

 nomenon ; I noticed that the inner part of the halo was about 10° from 

 the moon, that its breadth was about 3° or 4°, and that the brightest 

 colors were in the middle of the ring. Near the edge of the moon 

 the sky was of its natural color ; as well as I could determine, the 

 color of the concentric rings, which formed the halo, were as follows, 

 (beginning with the inner ring,) pale blue, yellovi', orange, and pale 

 blue again. 



That this and similar phenomena are occasioned by the watery 

 vapors in the atmosphere, is highly probable, and indeed it is ren- 

 dered almost certain from the following experiment, which I perform- 

 ed a short time after I observed it. I took a clear and smooth piece 

 of glass with parallel faces, and after gently blowing the breath upon it, 

 I held it up so as to look through it at the moon ; by means of the 

 aqueous vapor which was scattered in very small globules over the 

 surface of the glass, the moon's rays were refracted, producing all 

 the different colors which I had seen in die halo. The variety and 

 brightness of the colors can be modified by the quantity of vapor 

 which is attached to the glass, and the size of the ring will depend 



