CHAP. 2. 19. RAINBOW, PARHELION, &c. 99 



The ancient writers, too, spoke indifferently 

 of halones, circuli, coronae, halyses, parhelia, 

 and other the like phaenomena, as appears by 

 the works of Aristotle,* Pliny ,f Seneca,^ and 

 others. Aristotle appears to have written with 

 the most perspicuity of all of them. 



With a view to obviate the inconvenience 

 and misunderstanding which might arise from 

 the confusion or promiscuous use of terms not 

 sufficiently definite, I subjoin the following 

 classification, which, though imperfect, may 

 serve, till a better shall be found, to enable 

 meteorologists, in their journals, to express, 

 with tolerable precision, the kind of appearance 

 which they wish to commemorate. 



I endeavour to classify them (for want of a 

 better criterion) according to the apparent shapes 

 or figures which they present. It must be 

 remembered, that their various figures are the 

 result of the particular construction of the 

 cloud which refracts their light : a correct 

 attention, therefore, to these appearances, may 

 lead to a more perfect knowledge of the struc- 

 ture of the refracting medium. 



* Aristot. Meteor, lib. iii. cc. 2, 3. 

 t Plin. Hist. Nat. lib. ii. cc. 29, 30, 31, 32. lib. xviii. 35. 

 i Senec. Nat. Quaest. lib. i. cc. 2, 3, 4, 5, 6, 7. 



H 2 



