Strong and weak syllables. An accented syllable is strong,
An unaccented syllable is weak. A syllable that bears a secondary or a slight emphasis is half-strong. A very weak or slightly pronounced syllable is light.
Examples. In the words light, alight, lighter, the syllable light is, in each case, 'strong'; the syllables a- and -er are 'weak.' Chaucer sometimes uses such a word as light-e, in which the final -e may constitute a syllable of the verse, in which case it is 'weak'; or it may be elided or nearly elided before a vowel, in which case it may conveniently be described as being 'light.' In such a word as cónqueròr, there are really two accents. The true 'strong' accent is now on the first syllable; the 'half-strong' or secondary accent is on the third syllable; and it is not unusual to denote this by the use of an acute accent for the strong, and grave accent for the half-strong syllable.
[§ 99]. Three Latin terms. A word such as alight is often described as constituting an 'iambus' or 'iamb'; and I shall sometimes here use this term, but under protest. An iambus is properly a short syllable followed by a long one; whereas the English iamb is a weak syllable followed by a strong one, which is a very different thing. The confusion between length in Latin verses and strength in English verses is pernicious, and has greatly misled many writers on metre; for the difference between them is fundamental.
In the same way, such a word as lighter may be called a 'trochee'; but it must never be forgotten that, in English poetry, it means a strong syllable followed by a weak one, and is independent of the notion of 'length.'
Similarly, such a word as alighted, in which a strong syllable is situated between two weak ones, may be called an 'amphibrach.' The amphibrach plays a highly important part in English verse, though it is usual not to mention it at all. I shall use these three terms, iamb, trochee, and amphibrach, only occasionally, and for the convenience of the names; it being now well understood that I merely mean such groups of strong and weak syllables as occur in the English words alight, lighter, and alighted.
Having thus explained that an 'iamb' has nothing to do with long and short syllables, I shall nevertheless use, to denote it, the ordinary symbol
. Similarly, the symbol