on the Affections and Properties of Light. 373 
fringes exactly corresponding with those at B; and on chang- 
ing the figure of that part of the speculum’s edge between them 
and the sun, the fringes likewise had their figure altered in the 
very same way. On moving the speculum farther round, B 
came nearer to A in the image, according as the fringes on the 
speculum receded from that side which formed them ; and before 
they vanished alike from the speculum and image, they mixed 
with the colours at A in the image, and formed in their motion 
a variety of new and beautiful compound colours ; among these 
I particularly remarked a brown chocolate colour, and various 
other shades and tinges of brown and purple. Just before the 
frin es at B appeared, the space between A and C was filled 
with colours by reflexion, totally different in appearance from 
the fringes ; but I could not examine them so minutely as I 
wished in this broad image, I therefore made the following ex- 
periment. 
Observation 11. At the hole in the window-shut I held the 
speculum, and moved it to such an inclination that the colours 
by reflexion might be formed in the image ; they were much 
brighter and far more distended than the fringes, and were in 
every respect like the images by reflexion in the common way, 
only that the colours were a little better and more regular. 
They were also seen on the speculum as the third set of 
fringes had before been in Obs. 10.; but by letting the rays 
fall on the half next the chart, and inclining that half very 
much, I could produce them, though less distinctly, by a single 
reflexion. I now held a plain metal speculum so that the rays 
might be reflected to form a white image on a chart. On in- 
clining the speculum much, I saw the image turn red at the 
edge; it then became a little distended; and lastly, fringes 
3 C 2 
