Is this printing style common in Latin books?

Question

I was studying this book and it surprised me that the bottom right of every page includes the first syllable (?) of the next page's first word. An example below (Leges, Quif):

Following my curiosity, I searched other Latin books and found the same pattern in many of them (e.g here, here, here, or here) but not all (e.g. here, here, or here).

My questions:

1. Does this printing style have a name?
2. How widespread could we say it was? (perhaps a time-period?)
3. What was its function?

Answer 1

It is called a catchword and is common in manuscripts and in early printed books. Usually it appears only on the verso (even-numbered pages) and it allows the bookbinders to make sure that nothing is missing and that the pages are in the right order. Sometimes a catchword will appear (as here) also on the recto (odd-numbered page), for purely aesthetic purposes.

This means that in manuscripts in left-to-right scripts (like Latin) the catchword will normally be on the left-hand page, while in manuscripts in right-to-left scripts (Arabic, Hebrew etc.) the catchword will be on the right-hand page, as here: http://epapers.bham.ac.uk/119/162/Page_159.jpg

I have seen the Latin “vox reclamans” used in this sense, but am not sure whether this is already a mediaeval or only a humanistic usage. In French you say réclame.

Answer 2

This 'typesetting leader' was widely in use from early printing times but was not universal, as your examples indicate. In English, it occurs, for example, in Gibbon's History of the Decline & Fall of the Roman Empire and, as @Alex B comments on your question, it certainly carried on, in English at least, well into the nineteenth century.

As @fdb says, it is nothing more than a printer's checking device; it was once quite common, too, to buy a book as uncut or unbound papers — when it could be used as a sorting guide — either because the purchaser couldn't afford the cased version, or because he was rich enough to pay for a special binding to suit his personal taste.

It's hard to put a date for its extinction: I remember seventy years ago being given textbooks from the early twentieth-century — not in Latin, but in both English and French — which used the same device, but I should think that by that time it was at its last gasp.

Answer 3

I've even seen this in old books written in other languages as well (including Dutch, English and French). It's a thing they used to do, but usually stopped doing many years ago (it would be great if someone knew around what time this was, I suppose it has something to do with the (semi-)automation of printing).

The reason you see it more in Latin books is because relatively speaking more Latin books are this old.