Wow. Very cool to take this step back in time and see what young hackers in 1913 were doing. A lot of lame stuff, but some gems, like a line harmonograph, a “key card” for writing secret codes on post cards, handcutting gears and racks for models, a miniature “Pepper’s Ghost”, and a homemade water wheel. And that’s just in the first hundred pages, there are almost six hundred! Be sure to check out the PDF file.