Here is a link to a very informative book on the history of the sewing machine.
That may sound boring, but it is an invaluable reference for anyone who is interested in or collecting Vintage and Antique sewing machines.
I verified with Smithsonian personnel that it is out of copyright and in the public domain, so it can be redistributed publicly. I would have posted it here, as she suggested (the lady I spoke with from the Smithsonian), but it is too big, per limits imposed by this forum. This link will be changing, as she indicated that they would now be eventually making it available for download on their new digital library location (http://library.si.edu/digital-library/book) where it will be available in pdf, ebook and other formats.
Until then, feel free to download it or view it here, compliments of the Smithsonian:
The Sewing Machine - Its Invention and Development (by Grace Rogers Cooper)
Second Edition - 1976
Hope this helps someone else out there!
BTW - The author of this book had been the Smithsonian's curator over all things textile-related for years and years.