Today's English lesson

From the American Heritage Book of English Usage:

Possessives

We all know that in English you form the possessive by adding an apostrophe and an s, or sometimes just an apostrophe, at the end of a noun. Pronouns have their own possessive forms (my, your, his, her, its, our, their). Of course, another way to indicate possession is to use a prepositional phrase using of: the property of the town.

It is important to remember that possessive constructions are often used with inanimate nouns (a stone’s throw, the water’s edge). And although we call them possessives, they often do not indicate simple possession but a number of other relations. These include source or origin (the ambassador’s letter, Hardy’s novels), description or classification (the car’s speed, the stadium’s design, a month’s salary), and even purpose (a women’s college, boys’ clothing).

Listed below are some of the more troublesome constructions.

both
“A plague on both your houses!” We know this familiar curse from Shakespeare’s Romeo and Juliet. It means “a plague on the houses of both of you.” While this “both your” construction is still idiomatic, you can be more precise grammatically by saying of both. Thus you would say I gave copies of the book to the mothers of both (rather than both their mothers) or It’s the fault of both (rather than both their fault or both’s fault).

each other/one another
The possessive forms of each other and one another are written each other’s and one another’s, that is, with an apostrophe before the -s: The boys wore each other’s (not each others’) coats. They had forgotten one another’s (not one anothers’) names.

else
When a pronoun is followed by else, the possessive form is generally written with the ’s following else: That must be someone else’s (not someone’s else) book. Both who else’s and whose else are in use, but not whose else’s: Who else’s book could it have been? Whose else could it have been?

group possessive
You form the possessive for noun phrases by adding an ’s or an apostrophe at the end of the phrase: Jim and Nancy’s house, the Department of Chemistry’s new requirements, a three months’ journey. This construction gets cumbersome when the noun phrase is long, in which case you should probably use a prepositional phrase instead. Thus instead of saying the house that overlooks the bay’s property line, you should say the property line of the house that overlooks the bay.

of mine, of yours (double genitive)
People sometimes object to the “double genitive” construction, as in a friend of my father’s or a book of mine. But the construction has been used in English since the 14th century and serves a useful purpose. It can help sort out ambiguous phrases like Bob’s photograph, which could mean either “a photograph of Bob” (i.e., revealing Bob’s image) or “a photograph that is in Bob’s possession.” A photograph of Bob’s, on the other hand, can only be a photo that Bob has in his possession and may or may not show Bob’s image. Moreover, in some sentences the double genitive offers the only way to express what is meant. There is no substitute for it in a sentence such as That’s the only friend of yours that I’ve ever met, since sentences such as That’s your only friend that I’ve ever met and That’s your only friend, whom I’ve ever met are not grammatical.

whose
You can use whose as a possessive to refer to both animate and inanimate nouns. Thus you can say Crick, whose theories still influence work in laboratories around the world or Crick’s theories, whose influence continues to be felt in laboratories around the world. With inanimate nouns you can also use of which as an alternative, as in Crick’s theories, the influence of which continues to be felt in laboratories around the world. But as this example demonstrates, substituting of which for whose is sometimes cumbersome.