Rev. W. Scoresby on some remarkable Rainbows. 241 



the quantity absorbed. For, it would appear, according to Sir 

 Issac Newton's experiments, that, at an angle of 42° of inci- 

 dence (48° from the perpendicular), only from one-thirtieth to 

 one-fortieth part of the light impinging is reflected from water. 

 Is this proportion of light, then, sufficient for the production of 

 the iris ? There is good reason to suppose, I conceive, that even 

 this proportion is abundantly adequate to the production of the 

 phenomenon, because the light of the full-moon is occasionally 

 sufficient for the purpose ; yet that light, according to Dr Smith, 

 is little more than a ninety-thousandth part of the light of the 

 sun, or, according to M. Bouquer, not above a three- hundred- 

 thousandth part. In either case we see, that the light reflected 

 from the sea, when the sun has an altitude of 42°, is some thou- 

 sands of times greater than the quantity which is sufficient for 

 the production of the lunar iris ; consequently we may infer 

 that an inverted iris from the reflected rays of the sun, may oc- 

 cur even when the sun has the greatest altitude to which it ever 

 attains in any temperate or frigid climate 



This being the case, there seems to be reasonable ground for 

 supposing, that the reflection of the sun's rays from a perfectly 

 calm surface of water, may have a share also in the production 

 of some of the various phenomena of haloes, such as are not 

 otherwise explained, — a supposition which the resemblance that 

 figures 2 and 3 bear to some of the prismatic circles, renders 

 more than probable. ^ 



Tour to the South of France and the Pyrenees^ in 1825. By 

 G. A. Walker Aunott, Esq. A.M. F.L.S. & R. S.E. &c. 

 In a Letter to Professor Jameson. (Continued from the 

 preceding Volume, p. 275.) 



X HAVE taken notice of the Capouladoux Cyclamen, because by 

 some it is considered as very different from the C hedercpfo- 

 lium. The Montpellier plant is certainly the same as that 

 found in Corsica, and I believe not unfrequently along the shores 

 of the Mediterranean. It flowers in spring. In this respect it 

 agrees with that said to be found wild in Britain, but which has 

 probably escaped from some garden. I have never seen the 



