Yes, that's one of the (many) benefits of logging!
And in fact, there is a hiatus, because the introduction at the beginning is from a different "sub-book", where the pages are numbered using roman numerals. Typically the introduction would be written and typeset after the main book had been typeset, so its number of pages would not known in advance and that's why it uses a different numbering system.
So one finds a signature mark on pages 9, 25 41, 57, 73, 89, and then it starts again at page 93
109, 125, 141, 157, 173, 189, etc. (those numbers come from the filenames of the scans, not the numbers printed on the pages).
=> Another reason for not starting with the first signature mark and simply adding 16, is that would miss the changing of sub-book (or any irregular number of pages, for any reason).
And in fact, there is a hiatus, because the introduction at the beginning is from a different "sub-book", where the pages are numbered using roman numerals. Typically the introduction would be written and typeset after the main book had been typeset, so its number of pages would not known in advance and that's why it uses a different numbering system.
So one finds a signature mark on pages 9, 25 41, 57, 73, 89, and then it starts again at page 93 109, 125, 141, 157, 173, 189, etc. (those numbers come from the filenames of the scans, not the numbers printed on the pages).
=> Another reason for not starting with the first signature mark and simply adding 16, is that would miss the changing of sub-book (or any irregular number of pages, for any reason).