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

                                <s>XIII<\s> XIV An account of some cases of the production of 
colours, not hitherto described. By Thomas Young 
M. D. F. R. S. F. L. S. Professor of Natural Philosophy in the Royal Institution Read July 1, 1802. 
Whatever opinion may be entertained of 
the theory of light and colours which I have lately 
had the honour of submitting to the Royal Society,
it must at any rate be allowed that it has given 
<s>gi <\s> birth to the discovery of a simple and general 
law, capable of explaining a number of the phenomena 
of coloured light, which, without this law, would remain 
insulated and unintelligible. The law is, that “where-
ever two portions of the same light arrive at the eye by 
different routes, either exactly or very nearly in the 
same direction, the light becomes most intense when 
the difference of the routes is any multiple of a certain 
length, and least intense  in the intermediate state 
of the interfering portions; and this length is different 
for light of different colours.”
I have already shown in detail, the suffi-
ciency of this law for explaining all the phenomena 
described in the second and third book of Newton’s Optics,
as well as some others not mentioned by Newton.