From this same easy laxity of its nature all the other Vowel Sounds tend, in English particularly, when they are not accented, to fall back into this Natural Vowel; as in the following instances: Rom a n, brok e n, m i rth, mart y r, Bost o n, c u rd, etc.; words which we pronounce nearly Rom u n, brok u n, m u rth, mart u r, Bost u n, c u rd, etc.
— from The Continental Monthly, Vol 6, No 5, November 1864 Devoted To Literature And National Policy by Various