The Comic Latin Grammar A New and Facetious Introduction to the Latin Tongue

A diphthong is the sound of two vowels in one syllable. Taken collectively they resemble a closed fist-i.e. a bunch of fives. The diphthongs are au, eu, ei, æ, and oe. Of the two first of these, au and eu, the sound is intermediate between that of the two vowels of which each is formed. This fact may perhaps be impressed upon the mind, on the principles of artificial memory, by a reference to a familiar beverage, known by the name of half-and-half. In like manner, ei, which is generally pronounced i, and æ and oe, sounded like e, may be said to exhibit something like an analogy to a married couple. The human diphthong, Smith female + Brown male, is called Brown only.