Another Comma Problem

Gore Vidal was the last author to set me off by the niggardly use of commas (see “Commas”). The latest author to do so is J. K. Rowling, who, through six volumes of Harry Potter stories has mostly been a source of endless delight. Five hundred thirteen pages into Harry Potter and the Half-Blood Prince, however, I found myself rereading this sentence:

They had one of their rare joint free periods after Charms and walked back to the common room together.

It was immediately obvious that the sentence was wrongly punctuated, but it took a few moments to discover its meaning, and therefore, its proper punctuation. In the magical world of Harry Potter, odd collections of words are sometimes juxtaposed, and knowing this fact doubtless slowed my winnowing out unacceptable interpretations.

In the latest Harry Potter novel, Harry, Ron, and Hermione are sixth-year students at Hogwarts School of Witchcraft and Wizardry, and they are getting together in the Gryffindor common room during a class period for which none has a class scheduled, a situation that does not occur often. The sentence should, I think, read as follows:

They had one of their rare, joint free periods after Charms and walked back to the common room together.

As it appears in the book, the sentence might be read as if rendered as “rare, joint-free periods” (no one smoking pot) or “rare-joint-free periods” (a period free of rare joints, whatever that might mean). In context, of course, any reader would reject such interpretations but would nonetheless stand a good chance of getting well into the phrase “rare joint free periods” without a clear sense of what Rowling is getting at.

Even with the suggested punctuation, I am not completely happy with the sentence. One wants to put a comma after “joint” for additional clarity, but doing so belies how the sentence would be spoken and, in fact, its intended meaning. One would speak of “free periods” that are “rare” and “joint” (i.e., shared), not of “periods” that are “rare,” “joint,” and “free.” "Free periods” is really a compound noun modified by the two proceeding adjectives, and the phrase would be perfectly clear if written as “rare, joint free-periods,” except that “free periods” is not conventionally hyphenated. If one knows that the sentence is punctuated correctly, the reader, if paying close attention, should get the right meaning the first time if the single comma is used in the phrase. Particularly these days, however, such confidence is seldom justified.