[ 100 ] 
VI, Account of Jeveral Lunar Iris. By Marmaduke Tun flail, 
Efq. F. R, S. in Two Letters to Sir Jofeph Banks, Bart* 
F. R. S. 
Read May 30, 1782, and January 23, 1783, 
TO SIR JOSEPH BANKS, BART. P. R. S. 
DEAR SIR, 
A ! 
S I am ever happy to feize on any opportunity to exprefs 
jL JL my regard to yourfelf, and my attention to the Royal 
Society, I cannot omit this occafion of acquainting you of 
rather an unufual phenomenon feen here on Friday night laft, 
the 27th of February, between feven and eight, efpeciaLly as. 
it might probably be vifible only at a final! diflance. It waS 
an Iris lunaris , or Lunar rainbow, in tolerable diflindt colours, 
fimilar to a folar one, but more faint ; the orange colour 
feemed to predominate. I was unfortunately not a fpedlator 
myfelf; but can fufficiently rely on the authority, as a clergy- 
man in my houfe, and fome fervants, on whom I can depend, 
obferved it for near a quarter of an hour. It happened at full • 
moon, at which time alone they are faid to have been always 
feen. Though Aristotle is faid to have obferved two, and 
fome others have been feen by suellius, &c. I can only find 
two defcribed with any accuracy; viz . one by plot, in his 
Iliftory of Oxfordlhire, feen by him in 1675, though without 
colours ; the other feen by a Derbyfhire gentleman at Glapwell' 
6 . ' 
near 
