258 On Natural Magic. 
The following extract is taken from a letter addressed to the edi- 
tor by Mr. Wm. C. Woodbridge, the well known geographer, and 
dated Paris, Aug. 29, 1829. 
“In passing through Bonn, upon the Rhine, I visited Professor 
Noeggeratti, a distinguished mineralogist of that university. He 
spoke with great interest of our efforts in reference to mineralogy, 
and especially of the American Journal. He observed to me that, 
singular as it was, he had received through that Journal the first ac- 
count of an interesting fact in his own neighborhood. 
“‘ He had-heard many years since of a large mass of iron lying on 
one of the mountains termed ‘the Seven Mountains,’ in this vicin- 
ity, but which was. supposed to be a remnant of an old furnace. He 
designed to examine it, but delayed from time to time, and at length 
heard that a foreign officer had been there and taken away a large 
portion. He thought little more of it, until some time after, when 
he saw in the American Journal of Science, Col. Gibbs’ account of 
his discovery of a mass of meteoric iron on this very spot. He im- 
mediately went to examine the fact: he found that the mass had 
been cut up and put into the forge, but the smiths not having skill to 
work it, it was again thrown aside, and lay buried under a heap of 
scoria. Prof. N., after some search, discovered a very large quan- 
tity of this iron, and verified the existence of nickel, and the truth 
of the account which the American Journal* had been the medium 
of announcing to the world, of one of the largest masses of meteoric 
iron yet discovered.” 
Pi eS 
Arr. X.—On Natural Magic; in a letter to the Editor. 
Tue theory of accidental colors, so ingeniously developed by the 
successive labors of Scherffer, Epinus and Sir David Brewster, has 
been alluded to by the latter, in his treatise on natural magic, as 
probably adequate to account in some instances for spectral illusions, 
but for such only, in his opinion, it would seem, as may occur in 
full day light. Observation, however, has assured the writer, that 
appearances of this kind are not so peculiar to the strong light of 
day, nor so rare as seems to have been supposed. 
The retina of the eyes by the action of light upon it, has its sen- 
sibility wea weakened, which it will again recover completely, in the ab- 
are "3 Weaape inclined to think that the account here referred to, must have been 
that stiginilly published in Dr. Bruce’s Journal. 
