OBS. 20.—­The apostrophe was introduced into the possessive case, at least for the singular number, in some part of the seventeenth century.  Its adoption for the plural, appears to have been later:  it is not much used in books a hundred years old.  In Buchanan’s “Regular English Syntax,” which was written, I know not exactly when, but near the middle of the eighteenth century, I find the following paragraph:  “We have certainly a Genitive Plural, though there has been no Mark to distinguish it.  The Warriors Arms, i. e. the Arms of the Warriors, is as much a Genitive Plural, as the Warrior’s Arms, for the Arms of the Warrior is a Genitive Singular.  To distinguish this Genitive Plural, especially to Foreigners, we might use the Apostrophe reversed, thus, the Warrior`s Arms, the Stone`s End, for the End of the Stones, the Grocer`s, Taylor`s, Haberdasher`s, &c.  Company; for the Company of Grocers, Taylors, &c.  The Surgeon`s Hall, for the Hall of the Surgeons; the Rider`s Names, for the Names of the Riders; and so of all Plural Possessives.”—­See Buchan.  Synt., p. 111.  Our present form of the possessive plural, being unknown to this grammarian, must have had a later origin; nor can it have been, as some imagine it was, an abbreviation of a longer and more ancient form.

OBS. 21.—­The apostrophic s has often been added to nouns improperly; the words formed by it not being intended for the possessive singular, but for the nominative or objective plural.  Thus we find such authors as Addison and Swift, writing Jacobus’s and genius’s, for Jacobuses and geniuses; idea’s, toga’s, and tunica’s, for ideas, togas, and tunicas; enamorato’s and virtuoso’s, for enamoratoes and virtuosoes.  Errors of this kind, should be carefully avoided.

OBS. 22.—­The apostrophe and s are sometimes added to mere characters, to denote plurality, and not the possessive case; as, two a’s, three b’s, four 9’s.  These we cannot avoid, except by using the names of the things:  as, two Aes, three Bees, four Nines.  “Laced down the sides with little c’s.”—­Steele.  “Whenever two gg’s come together, they are both hard.”—­Buchanan.  The names of c and g, plural, are Cees and Gees.  Did these authors know the words, or did they not?  To have learned the names of the letters, will be found on many occasions a great convenience, especially to critics.  For example:  “The pronunciation of these two consecutive s’s is hard.”—­Webber’s Gram., p. 21.  Better:  “Esses.” “S and x, however, are exceptions.  They are pluralyzed by adding es preceded by a hyphen [-], as the s-es; the x-es.”—­O.  B. Peirce’s Gram., p. 40.  Better, use the names, Ess and Ex, and pluralize thus:  “the Esses; the Exes.”