Possessive Forms in English Grammar
W. J. Rayment / -- In formal writing, such as term papers, it is sometimes difficult to remember where to put that blasted apostrophe when trying to show possession. (To show possession is to show ownership.) This is frequently done in English, even when the law might not strictly construe an object as possessed by an individual, "your song, or his library book" come to mind. Yet there is a connection between the object and the "possessor" and that is what this little rule helps to show in writing and in speech.
The rule for forming the possessive singular (singular meaning that there is only one person place or thing doing the possessing) is simple: add 's. Be sure to follow this rule no matter what the final consonant. Joe's term paper, Harris's novel, the witch's spell. Note that the possessor and the possessee are both always nouns.
Yet there are exceptions to this rule of "apostrophe s". The exceptions are primarily proper names that come down from ancient times, and a few often used Biblical names, for example Jesus' crown, or Moses' staff. However, to avoid confusion, these terms are often replaced by such constructions as the thorny crown of Jesus, or the staff of Moses.
The possessives of several pronouns also form an exception, they are written without the apostrophe, as in hers, his, its, theirs, yours and ours. This is because of long usage and it also is an attempt to avoid confusion between these possessives and some contractions such as it's for "it is". (Yet the confusion on this matter continues to plague students of English everywhere.)
So, we have the singular, what about the plural? The "plural possessive" comes into play when more than one person, place, or thing happens to have ownership of an object. The rule is, again, simple: add s'. Just try to remember that when the apostrophe is before the "s" the possessor is singular, and when the apostrophe is behind the "s" the possessor is plural. (The clouds' linings were all silver.)
Yet, this is the English language, and there must be a few complications for every simple rule. When a plural possessive ends in an "s" tack an "es" on to the end of that and then add the apostrophe. For example the Harisses' car, the Joneses' cat, the Iveses' party.
Using the possessive form of nouns can sometimes look awkward. To avoid accusations of inadequate communication Strunk and White, in their ancient and authoritative, but readable book "The Elements of Style" recommend "recasting" such sentences. A simple way to do this is simply to reorder the words and use "of" as in the "Thorny Crown of Jesus" used above.