(Apologies if this isn’t the right forum. This is my first post here.)

I’ve noticed some books from the 1700s, for example this one,

http://books.google.com/books?id=sAoPAAAAQAAJ&pg=PA3

put part of the first word from the next page at the bottom of each page. I’d never seen this before!

Usually to learn more about something I type it into Google and see what pops up but I have no idea what this technique is called.

What was this next-word preview for? Something to help people who had trouble turning the page quickly?

This book also has codes like A2, B etc on the last line of most pages. What was this for? Something help binders put the sheets together? How did it work?