No, I'm not sure about copyright on most of them and how fair use would work for that. (I also have a map collection that is pretty awesome that suffers the same issue.)

That’s an interesting space. There should be a way to share just file hashes with a description and basic metadata for each of them, eg:

dea939...82f A scan of Newton’s personal notebook, page 13 (image from London Museum of History, 2013, 8000x6000 pixels)

That way people who like to build such collections would have ways to share and compare theirs, and see if they have anything missing from bigger datasets, etc. You could even imagine a wikimedia style commons to manage a repository of these hashes and associated metadata.

That's actually quite a brilliant idea! Now you have me thinking...