Let the sign (ˉ) denote that the vowel over which it stands is long, or independent, whilst the sign (˘) indicates shortness, or dependence. In such a case, instead of writing _not_ and _nωt_, like the Greeks, we may write _nŏt_ and _nōt_, the sign serving for a fresh letter. Herein the expression of the nature of the sound is natural, because the natural use of (ˉ) and (˘) is to express length or shortness, dependence or independence. Now, supposing the broad sound of o to be already represented, it is very evident that, of the other two sounds of o, the one must be long (independent), and the other short (dependent); and as it is only necessary to express one of these conditions, we may, if we choose, use the sign (ˉ) alone; its presence denoting length, and its absence shortness (independence or dependence). As signs of this kind, one mark is as good as another; and instead of (ˉ) we may, if we chose, substitute such a mark as (′) and write _nót_ = _nōt_ = _nωt_ = _nōte_; provided only that the sign (′) expresses no other condition or affection of a sound. This use of the mark (′), as a sign that the vowel over which it is placed is long (independent), is common in many languages. But is this use of (′) natural? For a reason that the reader has anticipated, it is not natural, but conventional. Neither is it convenient. It is used elsewhere not as the sign of _quantity_, but as the sign of _accent_; consequently, being placed over a letter, and being interpreted according to its natural meaning, it gives the idea, not that the syllable is long, but that it is emphatic or accented. Its use as a sign of quantity then, would be an orthographical expedient, or an inconvenient conventional mode of spelling. The English language abounds in orthographical expedients; the modes of expressing the quantity of the vowels being particularly numerous. To begin with these:-- The reduplication of a vowel where there is but one syllable (as in _feet_, _cool_), is an orthographical expedient. It merely means that the syllable is long (or independent). The juxtaposition of two different vowels, where there is but one syllable (as in _plain_, _moan_), is an orthographical expedient. It generally means the same as the reduplication of a vowel, i.e., that the syllable is long (independent). The addition of the e mute, as in _plane_, _whale_ (whatever may have been its origin), is, at present, but an orthographical expedient. It denotes the lengthening of the syllable. The reduplication of the consonant after a vowel, as in _spotted_, _torrent_, is in most cases but an orthographical expedient. It merely denotes that the preceding vowel is short (dependent). The use of ph for f in _Philip_, is an orthographical expedient, founded upon etymological reasons. The use of th for the simple sound of the first consonant in _thin_ and _thine_, is an orthographical expedient. The combination must be dealt with as a single letter.