18 May 2011

Pitman's Volume 14 - Gothic or Pointed Arch

Front Cover of Volume 14
Building Educator
Volume 14

by R Greenhalgh (Ed)

Published by Pitman & Sons Ltd
16th April 1927

No ISBN number

Extract from page 651
Gothic or Pointed Arch
These arches consist of two curves meeting at the apex of a triangle. The centres from which the curves are struck may be on or below the springing line, and in between or outside the springing points

Equilateral or Gothic arch
Fig. 55 - Volume 14, page 650
In the two examples shown, the centres are on the springing line. In the Equilateral arch they are on the springing points, and in the Lancet arch, they are outside these points

Isoceles or Lancet arch
Fig. 56 - Volume 14, page 650
Where the rise of the arch is less than the span, the centres will be below the springing line, a distance that can be varied to suit any required curve

The curves for each half of the arch are set out by the same process as for the segmental arch

The voussoirs, terminate at the apex, and on the centre line with a straight joint. It is not uncommon to see these arches constructed with a key-brick bird’s-mouthed at the apex of the soffit, and the bed joints radiating to one centre. In this case the construction is wrong. Properly constructed, there should be no key brick

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