Written Signs of Accent
§ 68. Here it is well to note that the ‘acute’ sign ´ is properly only used to mark an accented syllable; and the ‘circumflex’ ( ̂ or ̑ or ˜) is properly used only in languages with a Musical accent, and then to mark a syllable in which the tone rises on the first half of the syllable and falls on the second half, as in Gr. τοῦτο.
Unfortunately these convenient signs have come to be used in writing many languages to denote not Accent at all, but merely a particular quality or quantity of vowel; as in Fr. passé, cité to mark a particular kind of e; or as in Fr. hâter to mark a long vowel. And still more unluckily these actual signs are called ‘accents’ although in fact they do not in such cases denote Accent at all.
Ablaut
§ 69. In some period of the Indo-European parent language the Stress-accent upon one syllable robbed a preceding or following syllable of much of its quantity; words like Lat. dūco (older *déuco) ‘I lead,’ fīdo, older feido ‘I trust,’ show in their first syllable what is called the Normal form of the root; and this was preserved because in these verbs that syllable was accented in Indo-European. But there are words from the same roots, like dux, ducis ‘leader,’ fidēs ‘trust,’ which show a short form of the root, contaming only ŭ or ĭ instead of eu and ei; and this short or ‘Weak’ form
