236 



On the 17th of August a halo, or luminous 

 circle, round the Moon, fixed the attention of 

 the inhabitants, who considered it as the presage 

 of some violent earthquake : for, according to 

 the physical notions of the people, all extraor- 

 dinary phenomena are immediately connected 

 with each other. Coloured circles around the 

 Moon are much more rare in the countries of 

 the north, than in Provence, Italy, and Spain. 

 They are seen particularly, and this fact is sin- 

 gular enough, when the sky is clear, and the 

 weather seems to be most fair and settled. 

 Under the torrid zone beautiful prismatic colours 

 appear almost every night, even at the time of 

 the greatest droughts : often in the space of a 

 few minutes they disappear several times, be- 

 cause, without doubt, the superior currents 

 change the state of the floating vapours^ by 

 which the light is refracted. I sometimes even 

 observed, between the fifteenth degree of lati- 

 tude and the equator, small haloes around the 

 planet Venus ; the purple, orange, and violet, 

 were distinctly perceived ; but I never saw any 

 colours around Sirius, Canopus, or Acherner. 



While the halo was visible at Cumana, the 

 hygrometer noted great humidity ; nevertheless 

 the vapors appeared so perfectly in solution, or 

 rather so elastic and uniformly disseminated, 

 that they did not alter the transparency of the 

 atmosphere. The moon arose after a storm of 



