VII. An Account of a Singular Halo of the Moon. Com- 

 municated in a Letter from WlLLlAM HALL, Efq; ofWhite- 

 Hall, F. R. S, Edin. to Sir James Hall, Bart, F. R. S^ 

 Edin, 



[Read May 2. 1796.] 



Dear Sir James, Whitehall, near Berwick, April 2. 1796. 



ISend under cover the reprefentation of a very fingular Halo 

 of the Moon, (See PI. V.), feen here on the night of the i8th 

 of February laft, about 10 o'clock, and this T have hitherto delay- 

 ed, in order, if poffible, to gain farther information in the neigh- 

 bourhood concerning it. 



During the fhort continuance of the fmall halo, which did 

 not exceed 10 minutes after I got notice of it, I could not lay 

 my hands on any other inftrument to take the angles, but a Sis- 

 son's theodolite, w^hich, unluckily, having been conftrudled fo 

 as not to admit of a vertical angle fo great as the moon's alti- 

 tude then was, I laid it alide, not recolleding that it might have 

 meafured feveral of the fmaller angles. But I obferved fundry 

 marks, from which I took the angles as exadly as I could next 

 day. 



The moon was about S. W. and her altitude nearly 54°, 

 which of confequence was alfo the altitude of the limb of the 

 greater halo, where it was highefl, and where it paffed through. 



the 



