Weight slid along a suspended beam; thrust of octagon arches
Load on a pivot as a weight nears it, and how octagonal arches push their corner piers outward
The upper half analyses a horizontal beam hung from a pivot (polo): as a 4-pound weight is slid past the marks b, a and m toward the pivot, the load carried by the support falls from 8 to 6 to 5 to 4 pounds. Below, under the heading 'Foundation,' a partial plan of an octagon shows how the arches along its sides thrust the corner piers outward along lines h c and t d, driving pier m away from the octagon's center. The page couples a statics experiment with a structural observation about arcaded octagonal buildings.
On this page
Load felt at the support as a weight nears the pivot
A weight of 4 is moved along a horizontal beam past the marks b, a and m toward the fulcrum. With the weight at b the pole bears 8 pounds; drawn to a it bears 6, at m it would bear 5, and directly beneath the pole only 4. The load registered at the support diminishes as the weight approaches the pivot.
Octagon arches driving the corner piers outward
Under the heading 'Foundation,' the arches spanning the sides of an octagon are shown to push the corner piers outward. Lines h c and t d drive pier m away from the center of the octagon, illustrating the outward thrust an arcaded octagonal plan exerts on its angle-piers.