We have the same change of vowel in raper, for Roper.
"The Romance of Names"
Ernest Weekley
Mr R. W. raper, of Trinity College, Oxford, made the following statement to the Society for Psychical Research:- 'Just before Christmas 1894 I went over to Liverpool with one of my brothers and my sister.
"Occultism and Common-Sense"
Beckles Willson
A blind Emmentaler was made in Switzerland for export to Italy where it was hardened in caves to become a grating cheese called raper, and now it is largely imitated there.
"The Complete Book of Cheese"
Robert Carlton Brown
