I found this interesting corner, US Patent # 562,649, issued to John B. O’Riva in 1896. It is long out of protection, so anyone can make it. O’Riva states, “The object of this invention is to provide a binding for books which will be strong and durable without necessitating the destruction of the grain in the leather used for the binding.” It seems intended to be used for bibles with flexible covers. I appreciate O’Rivas sensitivity to preserving the beauty of the grain, which makes me think he came out of an arts and crafts background, rather than from the trade, who favored a very highly polished leather surface which made tooling easier.
This invention created a very smooth looking corner while preserving the natural grain and covered the puckering of the leather when it was pleated over the rounded edge. Possibly the leather could be left a bit thicker than a standard rounded corner. The overlapping layers of flexible board would also add some strength at this critical place.
It would be very interesting to find an example of this corner, I’ve never noticed one. Flexible board bibles like these tended to get carried back and forth to church every Sunday, and even if they were not read a lot, 19th C. ones are not as common as the ubiquitous large, illustrated Victorian Bible, for example. It seems it would be very difficult to enforce this kind of patent, especially if another binder had seen one of these and tried to copy it. But perhaps the patent was to protect the inventors idea against more large scale publishing house infringement. In this drawing, the grain pattern of the leather makes it seem like some kind of reptile skin, or other exotic such as shagreen. These types of leather are difficult to turn in neatly, let alone mold around a rounded corner.
Given the 1500 year history of the codex structure, to come up with something new, for something as basic as a corner, is genius. Except for hand held bibles, rounded corners are rather out of fashion these days, as are large squares, but if someone makes one of these, please send me a photo. I imagine this could also work with cloth, although I haven’t tried it. The cut edge of cloth along the curve could be vulnerable to wear, fraying and delamination. It might work better with paper. Hats off to O’Riva!