Building the World's First Computer: Babbage's Analytical Engine

Finally, I have a scheme for the gear design that seems to work. To cut right to the chase, here is a video showing a 4-digit number being flawlessly copied back and forth ten times between the two numbers on a digit stack, through both fixed and movable pinions  The "unit of time" is 0.157 seconds/digit, which is the speed Babbage proposed for Plans 16 through 28. The movable pinion also allows for shifting: multiplication or division by 10.  the mini-tester for digit wheels and long pinions How did I get here? At the time of my July 11th posting about gears, I was still plagued with excessive backlash, among other problems. Tim Robinson came over for the day, and we brainstormed ideas. We decided that the change to two teeth per digit had been a bad idea, and that we should go back to one. That simplifies the design because the gear teeth can again be used for locking, rather than having a separate locking wheel. But, critically, we would stay with two cycles of 0-9, which

An absolutely extraordinary partial model of Charles Babbage's Difference Engine #2 was built in 2017 by Piers Plummer at Royal Holloway, University of London. You can see it in action here: Amazing! It is a simplified version of the DE with 4 columns of 6 digits each, opened out more than the original design for better visibility. It is made of 3D-printed and painted nylon, laser-cut steel, and other standard modern parts. "And of course, it had to be powered by steam!" In order to learn from their detailed design, and to see that it gets the public exposure and preservation that it deserves, I asked for and received permission to make the CAD files available. They are now on GitHub here: https://github.com/LenShustek/AnalyticalEngine/tree/main/Piers_Plummer_DE The design files were made with Solidworks. For those of without access to that CAD software, I created and included JPG images of each of the parts and assemblies. This was a project with the Centre for Software