THE 



LONDON AND EDINBURGH 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



NOVEMBER 1832. 



LXI. Observations o?i some remarkable Optical Phdenomena 

 seen in Svoitzerland ; and on an Optical Phcenomenoyi 'which 

 occurs on vietxiing a Figure of a Crystal or geometrical Solid. 

 By L. A. Necker, Esq. Professor of Mineralogy at Geneva. 

 In a Letter /o Sir David Brewster. 

 My Dear Sir, 

 T MUST not delay any further fulfilling my promise of 

 -*■ writing to you, respecting the subjects of our conversation 

 in the too short moments I had the very great pleasure and 

 good fortune of seeing you in London. I am the more bound 

 to write soon, as my first object must be to correct a wrong 

 statement in the date of my observation of the parhelia, as 

 stated in my letter to Mr. Forbes (Edinb. Journal of Science, 

 No. 12. p. 251.). As this mistake, into which I was led by 

 trusting too much to my memory, and to some wrong infer- 

 ences, has had the effect of weakening some circumstances 

 which were in favour of your explanation, I am the more an- 

 xious to do it all justice, so that you may be in time to an- 

 nounce in your next Number the consequences of this mis- 

 take, for which I beg leave to apologize to you, to Mr. Forbes, 

 and to your readers, whom I have unwillingly led into error. 

 The true date of the day when I saw the parhelia, was the 

 1st of June 1830, as I observe by the little memorandum I kept 

 of this remarkable, and to me entirely new phaenomenon, — and 

 not the middle of July, as I stated in my letter, written lioni 

 memory in Edinburgh. Here I transcribe the whole note, 

 together with the little sketch which it contains. 



Third Seiics. Vol. 1. No. 5. Nov. 1832. 2 U 



