Digital BW, The Print

So I've been researching learning material for a semi related topic
and discovered Google Books. They have many old public domain books
available for free download. Thankfully the topic I'm reading about
hasn't really changed since the late 1800's to early 1900's. It's kind
of neat to see something listed as illustrations and engravings
instead of pictures or photos. So far most of the books that I've
looked at are from one of the Harvard libraries, but I expect there
are books from other places there too.