The Complete Guide to English Spelling Rules

(^) There are only a few commonly used words that end in ury.
(^) Even fewer commonly used words end in iry:
(^) And only two words use the yry spelling—porphyry and eyry. There are four ways to spell this rare
word—eyry, eyrie, aery, and aerie.
There are only about thirty words that use the double r, which occurs mostly after a short vowel:
(^) English is a constantly changing language, and it is possible that eventually most of the words in this
group will end in the simple ry. The archaic jewellery is already spelled jewelry, and wintery is
gradually being replaced by wintry. Perhaps we may one day lose the surplus e in tomfoolery.