Book dimensions revisited

Okay, maybe I was a bit hasty with my previous post on the subject. The appropriate dimension of a book is not always the length of time it takes to read. I posted a paperback to a friend in France this week and discovered that occasionally, the weight of the book (and before someone tries to be smart, yes it is the weight and not the mass - the post office measures it with a top-pan balance) is the appropriate characteristic. But on that note, I discovered that air mail is really rather cheap. Sending a ~780g package to Paris cost just £5.11. Bargain.