"Things You Wouldn't Know If We Didn't Blog Intermittently."
17 July 2010
"Jack-knife bridge," Buffalo, New York, 1905
What fascinates me about this lift-bridge is the mathematics of the counterweights. Notice how they roll down a parabolic track, so at the start of the lift, when the greatest force is required, they are dropping almost vertically; later, as the spans are partway up and less force is needed, the track starts to level out. Excellent.