I was noodling around, and found reference to a patent on an early “mirror screw” version of mechanical television. Don’t know that that is? Don’t worry, this link is more for me than for you.
REFLECTING AND SCANNING APPARATUS – Google Patents
Addendum: It’s amazing what you can find online. Archive.org has a scanned copy of A. F. Collins’ Experimental Television. Very cool.
Addendum2: Another book on early television. And another.