18th C. "Book"

“But then you realize that a ‘book’ back then wasn’t what we think of as a ‘book’ now. Back then, there were a plurality of book-sized formats that were, like octavo or the slightly-smaller duodecimo, pretty compact, so these ‘books’ were only a couple of thousand words long. (Like the totally fun The Art of Memory by Marius D’assigny, from 1706.) Authors who cranked out 40 ‘books’ were actually writing pieces that are closer to a long magazine article.It wasn’t until the 20th century arrived that nonfiction books started to congeal into the 300-page quantum, for a host of economic and cultural and industrial reasons.”

"Why 18th Century Books Looked Like Smartphone Screens" - http://bit.ly/1e3x4uv