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OF RIBBED VAULTSBY RIBS OF THE SAME CURVATURE.
The progress of vaulting has been from the cylin-drical to the hemispherical, from the groined vault tathe pendent dome, both in round-headed and pointedarches.
To determine the form of the separate ribs in avault by the slow and geometrical process of ordi-nates, or by the trammel and foci, was inconsistentwith the simplicity of practice, and led to a multiplicityof errors and a discordancy of workmanship. Themechanical construction of a circle is not higher thanthe level of the meanest capacity. The Romans,the Byzantine Greeks, and the Free Masons , suc-cessively tried the ellipse in architecture, and re-jected it. Again, necessity has introduced that curvein a branch of the art. But the false ellipse, intendedto simplify the practice, has been substituted for it,and has cheated the mathematician, disappointed thearchitect, and the flowing line of the conick sectionhas been missed.
Mr. Eton , in his Survey of the Turkish Empire ,observes, “ that the Turks have no means of cal-culating the lateral pressure of arches or of cupolas,though they generally err on the right side.” FromMr. Eton ’s story of the catenaria, and this paragraph,his knowledge may be doubted rather than that ofthe Turks. However theorists may question the