- a reduction of diphthongs plus schwa to diphthongs or monophthongs,
- a reduction of diphthongs to monophthongs,
- a change from a monophthong to an approximant,
- a change from one vowel class to another or
During all the time occupied by these changes - the shifting of vowel-sounds step by step along the scale, the expansion of simple vowels into diphthongs, and the compression of diphthongs into simple sounds - the written form of the language remained nearly steretyped as regards any indication of such changes, [...]
For earlier uses of the term it may be worthwhile to check "The Phonetic Journal", which was published from 1873 to 1905. It's a pity I don't have access to this journal.
BTW: I couldn't find anything on this W. R. Evans. The ODNB has but an entry on a clergyman by the same name. If any of my followers can elucidate me, I'd be most grateful.