I never really liked yapp edges, those overlapping floppy, flappy edges to a leather bound book, often a bible. Here’s a picture of my father’s prayer book, showing its creaky yapp edges. You can see a hole in the leather at the left. (I did a post about this book five years ago.) These flaps are semi yapps; full yapps would pretty much join when folded across the book’s bulk. 

John Carter’s ABC for Book Collectors tells us:

“Yapp, so called after the London bookseller who invented it about 1860*, is a style of binding (usually in leather, often limp) with overlapping edges or flaps on all three edges. Hence, yapp edges, meaning the flaps. The yapp style (no relation to the overlapping fore-edges of limp-vellum-bound books of the 16th and 17th centuries) is mostly used for books of devotion, slim volumes of verse printed for private circulation, ‘tasteful’ reprints of the RubáiyátPoems of PassionSonnets from the Portuguese, etc. The American term for this style (according to The Bookman’s Glossary) is divinity circuit or circuit edges.”

I always liked to imagine that it was the sight of yapp edges that put into the mind of some inventive Cambridge bible guy the idea of bibles with zippers. The zippered bible was patented by Cambridge University Press in 1933. The CUP blog tells the tale.

I have posted about the zip bible before.

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* Etherington & Roberts (see “Print glossaries” tab) give Mr Yapp’s first name as William.