UNfound:

The Book Typewriter was invented by Seward Aymor Dean of Minneapolis, Minnesota, ca.1892. It may have been produced or marketed in Rochester, New York. The Book Typewriter typed down on to the platen much like an Elliott-Hatch. 

Have some info about this typewriter? Have you found it? If yes, please email me at Antikey.Chop@gmail.com