Note.—In the following sentence from Wordsworth,—
“But oh, ye fountains, meadows, hills, and groves,
Forebode not any severing of our loves,”
many would consider the nouns in the first line as appositives of ye. It seems better to consider ye as filling the office of a limiting adjective. If we spoke about the fountains, we would say these fountains; speaking to them it is usage to employ the pronoun ye in the place of these.
Occasionally we find an adjective, adverb, phrase, or clause, explained by some sort of appositive; as, “Active and sprightly people are called mercurial, that is, born under the planet Mercury.” Here a participial phrase is in apposition with the adjective mercurial.
The appositive may even be used to explain a predicate, a use in which it very much resembles one use of the adjective clause; as, “The surplus beyond what was required for the support of the national worship was distributed in alms among the poor; a duty strenuously prescribed by their moral code.”—Prescott.
Introductory Word.—The appositive is frequently introduced or brought into the sentence by such words or expressions as namely, to wit, as, that is, or, in other words; as, “The whale is a mammal, that is, a warm-blooded, air-breathing animal that suckles its young.”
The introductory as is useful in limiting the application of a noun, signifying that it is to be considered only to the extent denoted by the appositive; as, “To the Esquimaux, the auk, as an article of food, is second in importance only to the seal.”
With this restrictive office as often introduces an appositive to a possessive pronoun; as, “As masters your first object must be to increase your power.”—Ruskin. It will readily be seen that masters is an appositive of your if the sentence is changed thus, “The first object of you, as masters, must be, etc.”
Such as or as often brings in the names of several individuals belonging to a certain class; thus, “The leaves and tender twigs are an agreeable food to many domestic animals, as the cow, horse, sheep, and goat.”—Thoreau.