PHILOSOPHICAL 
TRANSACTIONS. 
VII. Supplement to the First and Second Part of the Paper of 
Experiments , for Investigating the Cause of Coloured Con- 
centric Rings between Object Glasses , and other Appearances 
of a similar Nature, By William Herschel, LL. D. F. R. S . 
Read March 15, 1810. 
"When the intricacy of the subject, on which my two last 
papers have been treating, is considered, it will not appear 
singular that a few supplementary articles should be given. 
The compression of the account of the experiments into a 
small compass, where many material circumstances must be 
left unnoticed, may throw some obscurity on the results, which 
can only be removed by examining the subject in a fuller ex- 
tent, and from various points of view. I hope the following 
illustration and additional explanations will have the effect of 
clearing up what may possibly to some appear obscure or 
doubtful, in either the first or second part of my paper, and 
serve also to make the conclusions, which in the second have 
been chiefly supported by prismatic experiments, directly 
mdcccx. X 
