ms and Experiments on Light. 
brightness considerably dimmed, and formed the intersectii 
point of two rows of colored spectra, that crossed each « Yt 
nearly at right angles. One of the rows of spectra formed a 
acute angle with the shaft of the feather. at its outer extremity, 
and the other was nearly at right angles with the shaft. In endl 
colored spectrum the side nearest to the sun was a mixture of vio- 
let and the contiguous rays of the prismatic spectrum, while the 
side farthest from the sun was uniformly red. ‘The sun was 
slightly clouded when I made my first observations. Afterwards, 
when the sun shone perfectly clear, I observed that the angular 
spaces formed by the intersection of the two rows of colored 
spectra were occupied by less brilliant spectra, riewrgee in ee 
same order as the two rows above described. 
“On Monday, the Ist of July, 1839, I varied the euiperbaneiite 
above described, by making my observations upon the flame of a 
lamp, instead of the sun. I found an advantage in this, as it en- 
abled me to change the distance of the luminous object at plea- 
sure. In looking through the vane of the wing-feather of the 
wild pigeon at the flame of the lamp, I observed spectra, colored 
and arranged similarly to those which I saw when looking at the | 
sun. I first looked at the lamp at the distance of eight or ten | 
feet, and saw the two rows of colored spectra above described | 
entirely distinct from each other, with some faint appearances of 
spectra in the angular spaces near the lamp. As I approached 
the lamp, (holding the feather to my eye and looking at the 
flame, ) the colored spectra in the two rows gradually approxima- 
‘ted to the flame of the lamp and to each other, their colors at the 
‘same time becoming less distinct and approachitis to white light, 
while the spectra in the angular spaces became more perceptible. 
As I receded from the lamp, the spectra in the two rows receded 
from the central flame and from each other, their colors at the 
same time becoming | more distinet, and the | oe in the hd 
spaces gradually fading away. 
~ My next step was, in connection with my adliengety Prof 
‘Sturtevant, to introduce a small beam of light into a dark room 
by passing it through the vane of the wing-feather of the Jay. 
We observed colored aneeians arranged upon’a screen in the-miaar 
ner described above. In the y 
the eye wa th ak chamber and he retina the sereen. “iia 
teas OS 
os ty oe 
