William Frend (1757-1841)
Mathematician, non-conformist, social reformer, writer and Ada's early tutor
I am very much interested on the subject just now, but I cannot make out things at all, viz: why a rainbow always appears to the spectator to be an arc of a circle.
AL to WF, 15-3-1834 [B/LB/171, fols 127r-127v]