I started writing a new draft titled "Prof. Engel’s Marvelously Improbable Machines" and would love to get your feedback. I plan on publishing it on Thursday; I apologize for the shortness of notice. (Though one the nice thing about publishing in WordPress is that there's no real deadline, so comments received after August 17 will still be acted upon and acknowledged.) I also apologize for the crude illustrations. Over the next couple of days I hope to replace the photos of hand-written sketches by something less sloppy. Please leave your feedback here: https://mathenchant.wordpress.com?p=1802&shareadraft=5992885a0dab8 (keeping in mind that if you don't sign your comment I won't know who you, with the consequence that I won't be able to ask follow-up questions that your comments may elicit). Title: Prof. Engel’s Marvelously Improbable Machines Beginning: When a simple question has a simple answer, there's something unsatisfying about getting from the question to the answer via a route that's more complicated than either of them. You can just shrug off your dissatisfaction, or you can think harder and try to find a different route. This is a story of... Read more: https://mathenchant.wordpress.com?p=1802&shareadraft=5992885 a0dab8 Thanks, jamespropp