Goold Brown,
The Grammar of English Grammars
(1882)
“ The consonant R, called also a semivowel and a liquid, has usually, at the beginning of a word, or before a vowel, a rough or pretty strong sound; as in roll, rose, roam, proudly, prorogue. "In other positions," it is said by many to be "smooth" or "soft;" "as in hard, ford, word."--W. Allen. OBSERVATIONS. OBS. 1.--The letter R turns the tip of the tongue up against or towards the roof of the mouth, where the sound may be lengthened, roughened, trilled, or quavered. ”
