PHILOSOPHICAL 
TRANSACTIONS. 
I. The Bakerian Lecture. Experiments and Calculations relative 
to physical Optics. By Thomas Young, M. D. F.R.S. 
Read November 24, 1803. 
I. EXPERIMENTAL DEMONSTRATION OF THE GENERAL LAW OF 
THE INTERFERENCE OF LIGHT. 
In making some experiments 011 the fringes of colours accom- 
panying shadows, I have found so simple and so demonstrative 
a proof of the general law of the interference of two portions of 
light, which I have already endeavoured to establish, that I 
think it right to lay before the Royal Society, a short statement 
of the facts which appear to me so decisive. The proposition 
on which I mean to insist at present, is simply this, that fringes 
of colours are produced by the interference of two portions of 
light; and I think it will not be denied by the most prejudiced, 
that the assertion is proved by the experiments I am about 
to relate, which may be repeated with great ease, whenever 
MDCCCIV. B 
