XVI. Farther Experiments and Observations on the Affections 
and Properties of Light. By Henry Brougham, Jun. Esq. 
Communicated by Sir Charles Blagden, Knt. Sec. R. S. 
Read June 15, 1 797. 
Having laid before the Royal Society an account of a course 
of experiments on light, in which I had been engaged, and also 
of the conclusions which these experiments had taught me to 
draw, I proceed in the following paper to relate, the continua- 
tion of my observations ; which I hope may not prove wholly 
uninteresting to such as honoured the former part with their 
attention. I am first to unfold a new and, I think, curious 
property of light, that may be indeed reckoned fourfold, as 
it holds, like the rest, equally with respect to refraction, re- 
flexion, inflexion, and deflexion ; thus preserving entire the 
same beautiful analogy in these four operations, which we have 
hitherto remarked. I shall then consider several phasnomena 
connected either with this, or with the properties before de- 
scribed, and of which they afford some striking confirmations. 
I. 
Observation 1 . The sun shining strongly into my darkened 
chamber, I placed, at a small hole in the window-shut, a prism 
with its refracting angle (of 65°) upwards, so that the spec- 
