I’m not a forensic linguist, but I can point out a few things that usually help. First, the signature on the front cover of a 1928 first edition will often have a more formal, serifed script—think the tidy, looping capitals that H. G. Wells used in his own letters. The back‑cover signature is sometimes a bit looser, especially if the original owner added it later. If the handwriting on page 47 is more cramped, with hunching loops and a slightly different pressure, it’s probably a different hand. Next, look for any idiosyncratic flourishes—like an extra dot on the ‘i’ or a particular way the ‘t’ is crossed. Those are like fingerprints. If the signature on the front and back share that flourish, you’ve got a match. If the page 47 notes show a different flourish, you’re likely looking at a second owner or a later annotator. Finally, compare the ink. The book’s original ink is usually a darker, almost black tone, whereas later notes often have a lighter, almost grayish hue because of the fountain pen or ballpoint used in the 60s or 70s. If the ink on the covers is deeper than the page 47 notes, that’s another hint that the notes were added later. In short, compare the style and the ink. If both match, you’ve got a keeper; if not, you’ve probably got a curious fan who scribbled later. Good luck, and enjoy the detective work—book ghosts love a good mystery.

Sounds like a solid plan—just remember to keep a tiny, neat note in the margin about the spectrophotometer test; future archivists will thank you. Good luck, and may the handwriting secrets stay as stubbornly elusive as a lost chapter.