+RULE.—The Possessive Case of nouns is formed in the singular by adding to the nominative the apostrophe and the letter s ('s); in the plural by adding (') only. If the plural does not end in s, ('s) are both added. [Footnote: In Anglo-Saxon, es was a genitive (possessive) ending of the singular; as, sta:n, genitive sta:n-es. In old English, es and is were both used. In modern English, the vowel is generally dropped, and (') stands in its place. The use of the apostrophe has been extended to distinguish the possessive from other forms of the plural.
Some have said that our possessive ending is a remnant of the pronoun his. Phrases like, "Mars his sword," "The Prince his Players," "King Lewis his satisfaction" are abundant in Early, and in Middle, English. But it has been proved that the his in such expressions is an error that gained its wide currency largely through the confusion of early English orthography.
Professor Hadley has clearly shown that the Saxon termination has never dropped out of the language, but exists in the English possessive ending to-day.]
+Examples+.—Boy's, boys', men's.
+Remark+.—To avoid an unpleasant succession of hissing sounds, the s in the possessive singular is sometimes omitted; as, conscience' sake, goodness' sake, Achilles' sword, Archimedes' screw (the s in the words following the possessive here having its influence). In prose this omission of the s should seldom occur. The weight of usage inclines to the use of s in such names as Miss Rounds's, Mrs. Hemans's, King James's, witness's, prince's. Without the s there would be no distinction, in spoken language, between Miss Round's and Miss Rounds', Mrs. Heman's and Mrs. Hemans'.
+Remark+.—Pronounce the ('s) as a separate syllable (= es) when the sound of s will not unite with the last sound of the nominative.
+Remark+.—When the singular and the plural are alike in the nominative, some place the apostrophe after the s in the plural to distinguish it from the possessive singular; as, singular, sheep's; plural, sheeps'.
+Direction+.—Study the Rule and the Remarks given above, and then write the possessive singular and the possessive plural of each of the following nouns:—
Actor, elephant, farmer, king, lion, genius, horse, princess, buffalo, hero, mosquito, negro, volcano, junto, tyro, cuckoo, ally, attorney, fairy, lady, monkey, calf, elf, thief, wife, wolf, chief, dwarf, waif, child, goose, mouse, ox, woman, beau, seraph, fish, deer, sheep, swine.
Compound names and groups of words that may be treated as compound names add the possessive sign to the last word; as, a man-of-war's rigging, the queen of England's palace,[Footnote: In parsing the words queen and England separately, the ('s) must be regarded as belonging to queen; but the whole phrase queen of England's may be treated as one noun in the possessive case.] Frederick the Great's verses.