An Account of Some Cases of the Production ofColours, Not Hitherto Described. Thomas Young.

                                the appropriate dimensions deduced from the phenomena of 
thin plates. Hence it happens, that when a line of the 
light proceeding to form an image of the rings of colours of thin 
plates, is intercepted by a prism, and an actual picture is formed,
resembling the scale delineated by Newton from theory, for estimating 
the colours of particles of given dimensions, the oblique spectrums,
formed by the different colours of each series, are not straight, but 
curved, the lateral refraction of the prism separating the violet 
end more widely than the red. The thickness corresponding 
to the extreme red , the line of yellow, bright green, bright blue,
and extreme violet, I found to be inversely as the numbers 
27, 30, 35, 40, and 45, respectively. In consequence of Dr. Wollaston’s
correction of the description <s>division <\s> of the prismatic spectrum, compared 
with these observations, it becomes necessary to modify the 
supposition that I advanced in the last Bakerian lecture respecting 
the proportions of the sympathetic fibres of the retina; substituting 
red, green, and violet, for red, yellow and blue, and the numbers 
7, 6, and 5, for 8, 7, and 6.
The same prismatic analysis of the colours of 
thin plates, appears to furnish a satisfactory explanation of 
the subdivision of the light of the lower part of a candle <s>observed 
also by Dr. Wollaston <\s>: for, in fact, the light transmitted through 
every part of a thin plate, is divided in a similar manner 
into distinct portions, increasing in number with the thickness 
of the plate until they become too minute to be visible. At the 
<s>Opposite <\s> thickness corresponding to the ninth or tenth  <s>the tenth or eleventh <\s> portion of red light, the number 
of portions of different colours is <s>six<\s> five, and their proportions, as 
exhibited by refraction, are nearly the same as in the light of a 
candle, the violet being the broadest. We have only to suppose