When in doubt respecting the form of any of the above, consult an unabridged dictionary.
14. Case. There are three cases in English: the Nominative, the Possessive, and the Objective.
The Nominative Case; the form used in address and as the subject of a verb.
The Objective Case; the form used as the object of a verb or a preposition. It is always the same in form as is the nominative.
Since no error in grammar can arise in the use of the nominative or the objective cases of nouns, no further discussion of these cases is here needed.
The Possessive Case; the form used to show ownership. In the forming of this case we have inflection.
15. The following are the rules for the forming of the possessive case:
1. Most nouns form the possessive by adding the apostrophe and s ('s); as, man, man's; men, men's; pupil, pupil's; John, John's.
2. Plural nouns ending in s form the possessive by adding only the apostrophe ('); as, persons, persons'; writers, writers'. In stating possession in the plural, then one should say: Carpenters' tools sharpened here, Odd Fellows' wives are invited, etc.
3. Some singular nouns ending in an s sound form the possessive by adding the apostrophe alone; as, for appearance' sake, for goodness' sake. But usage inclines to the adding of the apostrophe and s ('s) even if the singular noun does end in an s sound; as, Charles's book, Frances's dress, the mistress's dress.