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of the four vowels (ǎ, à, ě, ŏ) being liable to a palatal or labial modification, we may on physiological grounds expect eight different compound vowels.
This can best be represented by a diagram:
Diphthongs with ǎ as base.
If the short a is quickly followed by i and u, so that, as the Hindus say, the guttural is mixed with the palatal and labial vowels like milk and water, we get the diphthongs ai and au, pronounced as in French. They correspond in sound to the Italian e and o, and to the English sounds in sailor and home.
Diphthongs with A as Base.
If the a, as the first clement, retains more of its independent nature, or is long, then +i pronounced together give the German diphthong ai, as in pic and buy; a + give the German diphthong an, as in proud.
