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ms it ‘S 
| Ane. SAW-Obestviliines and sitisiebecaie on cndahes by pate 
vet Apams, M. D., Professor of te sg et vee 
in [linois College, enmnepesmenoy: oe 
veka in July, 1838, while ona , Neuieeniee ke excursion, I 
accidentally noticed the enn Savion of a bird lying upon the 
ground ; and being struck with the delicacy of its tints, I took it 
up to examine it. Observing that the vane of the feather. ap- 
peared. very thin and nearly transparent, I held it between my 
eye and the sky, which was very clear with the exception of a 
few fleecy clouds, that contrasted finely with its rich blue. I 
was very much interested to observe, that the clouds and all light 
colored objects, which were highly illuminated, were seen through 
the vane of the feather beautifully fringed with the colors of the 
rainbow. I.supposed that this phenomenon depended upon the 
‘peculiar structure of the vane of the feather, and intended to in- 
vestigate it as soon as I could find leisure. I did not, however, 
resume the subject till accident again called my attention to it. 
About the 20th of June, 1839, while walking in the College 
grove, I happened to observe lying upon the ground some wing- 
feathers of the Jay, which reminded me of my former experiment. 
I collected the feathers, and after observing the same phenomena 
that [ had noticed on the former occasion, I held the vane of the 
feather between my eye and the sun, and was greatly surprised 
at the gorgeous display of colored spectra that were seen through 
it, arranged in the most exact mathematical order, ‘The sun was 
seen in its natural position, slightly tinged with red, with its 
* To the Editors of the American Journal of Science and: Arts, 
_ Messrs. Editors—When “ Observations and Experiments on Light’ were for- 
warded to you for a in the Journal of Science, I was not aware » that 
‘raunhofer had anticipated the leading investigations of that communication. 
Pressing engagements, and frequent attacks of intermittent ree prevented me 
from making so full an examination of the works of others on the subject as w 
i I have since ascertained, that Fraunhofer has gerinstes the Ladin 
results of | my observations, in a series of experiments m made by him by passing a 
Beata being es through gratings, and examining the épectra produced through a 
'Mleaebehon Light, § 740, et seq.) Ido not find, however, that the 
effect of the feather upon light has been before noticed, or that Fraunhofer ever 
exhibited the spectra upon a screen. You will oblige me by pros eg as a 
note to my communication. age &e. Sam 
Minois 
College, May 21, 1 
