In this fun vintage "infographic," the engineers who worked on Scotland's Forth Bridge set up their own human demo of the design principle behind the iconic structure. Sir Benjamin Baker (right) and Sir John Fowler (left) serve as the structure's cantilevers, and the load (Japanese engineer Kaichi Watanabe in the center) is supported by a balance of tension (in the men's arms and the ropes to the anchors on both ends) and compression (in the men's torsos and the sticks gripped in their hands).
This innovative balancing of forces helped the Forth Bridge reach a total span of 8,296 feet, which was good enough to hold the title of world's "longest single cantilever bridge span" for nearly 30 years. To this day, it's still the second longest span, right behind the Quebec Bridge. Other structures built according to this principle include the Minato Bridge in Osaka, Japan and the Tappan Zee Bridge in New York.
· Humans demonstrate how a cantilever bridge works (circa 1890) [Boing Boing]
· All History Lessons posts [Curbed National]