The Catenary Arch
Most people seem to think that arches were invented by the Romans, but this is
not true. For instance, the Inuit peoples of the far north have been using arch and dome concepts to build igloos since before recorded history. A dome is a three-dimensional application of the arch, rotated about the center axis. Igloos are built as domes, typically with an arched tunnel entrance.
It was the Romans, however, who made the arch famous and explored its use in a
variety of architectural settings. One of the most well known is the Roman Aqueduct, the Pont Du Gard, (french for "Bridge of Gard - Gard is the name of the river under it) This arch bridge carried water to the town of Nimes, France.
Arches were used because of their stability and strength, but the Roman arch was a simple half-circle supported on pillars. It was easy to build, but not the strongest type of arch. A much stronger shape is the parabola, and the catenary curve is even stronger and more stable than that.
This arch project uses the catenary curve to make a pair of arches at 90 degrees to each other, for a strong, stable and very attractive structure.
This completed model will stand fourteen inches tall and thirteen inches wide. It can be built in one evening, either with or without glue (use glue for a permanent structure, or without glue for a 3-D puzzle). It makes a great display for train sets, with potted plants, or on your mantle or bookshelf.
