Princeton professor Anthony Grafton has an actual book wheel in his office. One can see it behind him on the first picture on the right: <a href="http://www.princeton.edu/~paw/archive_new/PAW06-07/11-0404/features_grafton.html" rel="nofollow">http://www.princeton.edu/~paw/archive_new/PAW06-07/11-0404/f...</a>