I have been experimenting a little with visualising quire structures recently and have now added a link to such a visualisation in the description of manuscript KBR 5100-4. You will be able to navigate a schematic illustration of the quires that contain Félire Óengusso based on my analysis of the manuscript last February. Images are courtesy of the Koninklijke Bibliotheek in Brussels and the schematics tool used is the Schoenberg Institute for Manuscript Studies Collation Modeler (VisColl), the wonderful work of Dot Porter. The visualisation can’t currently display large quires (such as we see often in Irish manuscripts) very well, but Dot tells me there is a new version on the way that can, at which point I will update the link 🙂
If you are not sure what I mean by quire and quire structures, this next section is for you!
When discussing how a manuscript is put together, scholars often have to refer to its structure. This is not unlike modern book. In fact, if you have a hardback to hand while reading this, I suggest taking one out and looking at it from the top. When you look closely at the point where the pages meet the spine, you will very likely see that the pages were not pasted together as a loose stack, but as small groups or booklets of pages. (Depending on the publisher.) Like in this book on the right for example.
This is true also for most manuscripts, except that we do not always call the leaves of a manuscript pages (and where they are called pages, this is because they have been numbered as pages).
Most manuscripts consists of similar ‘booklets’ bound together, which we call quires (or gatherings). Each quire consists of a number of sheets or folded together. A simple way to create a small quire or booklet yourself is to take a number of A4 or A3 sheets, say four, place them on top of each other, and then fold the bundle in half across the short side. You will now have a booklet with four folded sheets or bifolia and eight folia: each folded sheet is called a bifolium and forms two leaves or folia in your booklet.
If you were to paginate these like in a modern book, you would number them 1 to 16, but with manuscript folios we normally refer to the front and back side, the recto and the verso, of the folio. This is called foliation. Instead of having a page number 1 on the first leaf of your booklet, you would refer to it as folio 1r, and to the backside as 1v.
To create such neatly folded quires, a scribe would have taken a sheet of paper or vellum (animal skin) and folded it to right size. This might mean folding a sheet more than once. For instance, if you take one sheet of paper, fold it in half, and then fold it in half again, you have a quarto. Your quire now has four leaves or folia.
If you look again at the image of the quire structure of KBR 5100-4 above, you will see, on the left, a series of curved lines with numbers. This schematic illustrates how the part of the manuscript that we call quire 7 fits together. Each of these lines represents a folded sheet or bifolium and each folio is referred to by recto and a verso. In the visualiser loose, individual images have been stitched together, but it shows you each side of the whole bifolium. This way we can visualise the structure of the manuscript without having to take it apart.
If you want to know more about manuscript terminology and making manuscripts, you could start here:
https://blogs.bl.uk/digitisedmanuscripts/2017/09/a-rough-guide-to-making-a-medieval-manuscript.html
https://www.bl.uk/catalogues/illuminatedmanuscripts/glossary.asp
(this page was edited in 2020 to add an image)