Agriculture Reference
In-Depth Information
numbered arch was then drawn out on paper following the same system of
measuring the length of the intrados and extrados, working equally either side
of the vertical centre line to each opening; which also helped to determine
the individual skewback measurements and geometrical angles. At the centre
line, which in most cases ran up through the centre of each 'keybrick', we also
measured the face height of each arch. Upon each of the overall arch draw-
ings we recorded the positions of the individual voussoirs, joint sizes and face
bonding; the latter varying between half and quarter bond. Once fully drawn
and bonded every voussoir was uniquely numbered for its position on either
side of the arch e.g. the first springing brick on the left side being a stretcher,
with its mirror-image on the right-hand side would be numbered LS 1 and RS
1 respectively; and so on. Finally we measured and established the radial cen-
tres, or 'striking points', of each arch along their respective centre lines; which
were plumbed down onto battens placed within, or below, the openings. Nails
were then fixed at all striking points so lines could be strained from them to
check the skewbacks and the radial alignment of the voussoirs of each arch,
and ensure accuracy of re-building to the original positions.
Once satisfied that each of the arches had been properly recorded we basi-
cally followed a similar sequence on each one. Timber 'centres' were placed
and wedged tight up to the soffits of openings built with recessed reveals, but
this was not necessary on the flat arches built directly on top of the timber
window frames. Upon either of these supports the centre line was measured
and drawn, then the positions of all the voussoirs were marked on them with
a pencil and numbered to correspond to that on its unique drawing. The first
few courses of standard face brickwork over the top of the arch, having been
recorded was then carefully disassembled in order to gain full access to dis-
assemble the arch, each brick marked for re-locating back to its original posi-
tion. Above the arch was positioned and fixed a horizontal timber batten to
serve as a 'profile tree' and onto this the centre line was plumbed-up from the
turning piece or window head, and the positions of the voussoirs through the
intrados marks from lines strained from the striking point.
All the arches were carefully dismantled from the key to the skewbacks in the
reverse order of how they had been assembled, and each voussoir was scribed
to have a number corresponding to the drawing. These were then scraped
clean of old mortar and placed in a protective numbered box and removed for
repair and individual replacements to be bespoke cut where necessary.
The remedial work basically involved carefully re-rubbing the face smooth
to remove all pitting, new bricks being introduced only to replace those bricks
that had completely shattered or severely eroded. These were worked to match
those they were replacing, being scribed to the templets and cut in the tradi-
tional manner. This completed, the arch could be reassembled within the box
to be brought back to its opening.
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