Walter Thomas Rogers. A Manual of Bibliography. London: H. Grevel & Co., 1891 ( p. 95)
Although a nineteenth century fine binding should operate as Rogers describes, many earlier books were rebound at the time and forced into this style of binding; not a good thing for a parchment manuscript, for example. However, this ideal in binding is quite difficult (impossible?) to achieve, since the binder generally does not have control over important variables such as leaf size, drape, thickness, and number in each signature.
In fact, I’m not sure if I’ve ever experienced a “good” binding such as this. While the technical aspects of craft were high, the quality of materials was generally low. Possibly one of the most interesting aspects in making historical models is an attempt to understand and recreate book movement from various time periods. This is somewhat speculative since many of the details of craft techniques are unknown, and modern materials differ substantially from historic ones. Materials also change over time: “Binding materials stiffen with age; Binding materials weaken with age; Binding materials are weakened by use; Binding materials are made more supple by use.” Tom Conroy’s, The Movement of the Book Spine (Book and Paper Group Annual, Vol. 6, 1987) is required reading for anyone interested in this topic.
Movement in and of itself is not the most important aspect of a book, but it is critical to understand so that a book can be safely handled, used and displayed. There is also fascinating research on the relation of haptics, memory, and learning. Much of a book conservator’s work is concerned with increasing and preserving— sometimes incrementally— a book’s movement.