Front Cover of Volume 14
Volume 14
by R Greenhalgh (Ed)
Published by Pitman & Sons Ltd
16th April 1927
No ISBN number
Extract from page 651
Semicircular Arch
This is one of the simplest kinds to set out. The springing line is drawn and the span of the opening marked off on either side of a centre line
The inner and outer curves of the arch are struck from the point where the springing line and centre line intersect
As all the bed joints will radiate to the centre from which the arch is struck, join up these divisions to the centre
The wedge-shape between any two of these radial lines will contain the mould of the voussoirs. The key-stone is usually taken for the purpose of making this mould, shown by hatched lines in the drawing
The mould of the voussoirs is the template for cutting each brick. If it is a rough arch, where the bricks are not trimmed, then the divisions need to allow for at least 5mm mortar joint at the intrados
This is one of the simplest kinds to set out. The springing line is drawn and the span of the opening marked off on either side of a centre line
The inner and outer curves of the arch are struck from the point where the springing line and centre line intersect
Semi-circular arch
Fig 53 - Volume 14 page 649
Measure the width of the bricks that are to be used and divide the outer curve, or extrados, into equal divisions. In marking these divisions, start from the key brick and work down to the springing lineFig 53 - Volume 14 page 649
As all the bed joints will radiate to the centre from which the arch is struck, join up these divisions to the centre
The wedge-shape between any two of these radial lines will contain the mould of the voussoirs. The key-stone is usually taken for the purpose of making this mould, shown by hatched lines in the drawing
The mould of the voussoirs is the template for cutting each brick. If it is a rough arch, where the bricks are not trimmed, then the divisions need to allow for at least 5mm mortar joint at the intrados
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