The image above is a page from Alexander Graham Bell's sketchbook, a self-portrait from the 1870's, is just one page from the large collection of the inventor's papers, now housed at the Library of Congress. Bell's sketches which document the invention of the telephone are the most fascinating of the lot, and happily, the Library has digitized them and made a large selection of them available online.

Avaak Vue Gen 2 wire-free video monitoring hands-on