Just updated the answer page with the solution to number 833, it's a wrench
for twisting wires, patent number 338,659.


Also updated the answer for the optic traffic detectors, I sent an email
asking how they worked and the reply stated that these detectors use simple
video technology to capture an image of the approach. When a vehicle enters
the detection zone this image changes and the camera sends a signal to the
controller that a vehicle is in a particular lane waiting for a green light.

http://pzphotosan145t-5.blogspot.com/


Rob