This post: just some written-up notes collecting together things I’ve found useful in understanding manuscripts’ physical structure.
There are three kinds of evidence which I was taught to use. First: string. In the centre of a quire, between the two leaves which form the innermost bifolium, a string usually surfaces, runs down the gutter and then returns back to the depths of the binding to the sewing supports. Sometimes (but not always) the book will open naturally wide enough that this string will be visible. Equally, sometimes the binding is so tight that you never catch sight of any of these pieces of string.
Second: catchwords: on copying a quire’s last page (i.e. the reverse side—the verso—of the last leaf of the quire) scribes commonly wrote the words which would go at the top of the next page in the bottom margin. These are an aid to the binder and anyone else who has to deal with the quires before they are bound: if the quires became disordered, by consulting the catchwords and the first words of each quire, you can reconstruct their proper order rapidly, without having to read the main text. When catchwords are present they usually mark the end of the quire, although they can also appear on pages within quires. (As an aid to reading aloud?)
Third: quire or leaf signatures. Catchwords are intended to help keep the quires in order. But (as you can imagine) there are also potential issues with keeping the bifolia within a quire in order. And so one might number each bifolium, or even each leaf.
Catchwords and quire signatures, unlike the string used in the binding, can survive even a complete rebinding and disordering of the manuscript. But later trimming of books’ edges can remove either or both kinds of evidence. In practice I use all three kinds of evidence, depending on what’s available, but I’m fond of the string as it’s the evidence most closely linked to the book’s structure itself. Catchwords and quire signatures show how the book was expected to fit together, but not necessarily how it was actually put together.
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As for what I’ve found useful while working out manuscripts’ collation: diagrams! Diagrams, diagrams, diagrams. It’s one thing to learn about quires and quite another to be able to visualise the quiring of the book that’s in front of you. I don’t know what anyone else’s experience is likely to be, but I only began to get faster when I started drawing diagrams. Nowadays if I’m consulting a manuscript in a library I often photograph my hand-drawn quire diagrams with my phone and then email the image to myself to create a rough’n’ready electronic copy.
Imagination is also important: I find it useful to handle the leaves which form a bifolium and remind myself that somewhere, down behind the gutter of the opening, they join up. I’ve also found that the ten 1–0 number keys laid out above a standard QWERTY keyboard can be useful in visualising a quire of ten leaves or fewer: I assign each leaf to a number and this helps me ‘see’ them all at once.
While giving one of the Bodleian’s masterclasses, I think Orietta Da Rold mentioned that if you’re trying to work out which of two other leaves a leaf is conjugated with, you can look for shared dirtiness or discolouration on one side, or marks or scars that run across the bifolium’s fold. Like most manuscript tips I’ve heard this seems obvious once you know it, but hadn’t occurred to me before.