The papers from the
preparation of BUILDING BROCHS, see -
https://voussoirs.blogspot.com/2019/04/building-brochs.html,
were lying around as the coffee was poured the next morning; the pens
were still there. One soon discovers the value of a mess. The eye
looked at the preliminary round house plan again: might the posts be
erected first? A sketch of the posts was made. Yes – it seemed
likely: the centre could be identified and the hexagon marked out on
the ground with a peg and a length of string. Then the holes would
have to be dug and the poles erected, aligned and braced. This could
all be done without the encumbrance of the walls that not only
limited the construction area, but also restricted access to one
location. The idea had practical merit.
Typical round house plans
The timber frame was
drawn as it might look. From this start, the set out of the circle
for the stone walls could begin. The timber frame became a permanent
reference marker for location and orientation. Pegs, string and a
template was all that was required to mark the circle. This could be
managed progressively too, as the wall was constructed. It would be
difficult to maintain the markings of the set out of the complete
circle on a building site. With the core identified, the whole round
house was able to be set out piecemeal. Once the walls had been
erected, the roof could be finished, linking the walls to the central
frame conically. It made practical sense: the challenges of building
sites do not change with time. It is an environment in which precise
set outs have to be achieved in the context of a dirty shambles.
Might the broch have started similarly?
Typical broch plans
The rough sketch for
the process of setting out concentric circles was picked up and
perused. The pen began its scribblings. Peg locations could easily be
marked out after the erection of the hexagonal frame that defined the
centre. Parts of the walls were drawn in; a section was sketched.
Once the braced frame was in place, the profiles of the walls could
be set up radially on the ground and the walls begun. Once the first
profile height had been completed, the first lift could occur. This
would entail temporary scaffolding: the pens scrawled out a
possibility. Inside and outside would have to align so that the
profiles could be supported. The first lift would have the solid
stone base as the support.
Stones could be
lifted up to the working level of the scaffold. Once finished, the
first lift would have reached the scarcement level. The scarcement
would have been installed at this time as projecting slabs of stone;
then joists could be put in place: but! - the scarcement needs mass above it for it to be a solid, stable, load-bearing element.* A
temporary prop is needed to support the scarcement or the joists
until the upper inner wall has sufficient mass to counter the floor
load. Here one thinks of the temporary props used for concrete work;
these stay in place until the concrete has cured and gained
sufficient strength - usually about 28 days. Once the joists are in place, the next set of
hexagonal poles could then be positioned. These would have to be
joined so as to maintain the geometry of the hexagonal reference used
for the set out. The doodling seemed to be giving substance,
clarification to some lingering unknowns, even revealing new issues
that had never before been noticed.
The beginnings of
yesterday’s broch section scribble was picked up. Why not sketch in
the parts here to consider the impacts? Ladders were drawn on the
timber frame and a different roof was drawn in: maybe? A red pen was
picked up to consider the scaffolding. Temporary scaffolds would be
required inside as well as the permanent framing. These platforms
needed to be co-ordinated with the temporary external scaffold to
provide support for the wall profiles: but what holds the profile up
between the walls? The stone ties could do this. Ah! Each lift in the
scaffolding could also mark the position of the bridging stones that
would be installed along with the top stones of each lift.
Interesting.
The progressive lifts of the dry stone work are illustrated in this cross section.
The piles of stones
were marked in to test the idea. Yes, the rocks could be placed at
the working levels as things progressed. The space inside the
hexagonal framing would be available for lifting, as well as for
general access: but by this time, the broch entry would have been
formed, limiting easy access to this lift area. Maybe the stones were
transferred from the massive external piles with a lifting device
that could deliver stones to the working platforms externally, and
swing them over the walls onto the central, internal scaffold. This
appeared to be a more practical and flexible arrangement. The floor
joists were drawn in on yet another scribbled plan to see how they
might set out. The radial pattern would concentrate the timbers at
the hexagonal frame, and limit the minimum spacing. This seemed not
to be a problem; but what material was used for flooring? Timber
planks seems to be the first guess, but was this wood available?
Might mats and clay have been used? The material would finally define
the required joist spacing.*
Diagrammatic structural diagrams do not clarify or resolve thinking on brochs;
they only confuse, confound, and complicate.
The more one
scribbled, the more things seemed to come together, or be further
challenged. Everything appeared to confirm that the building of the
broch started with the erection of the hexagonal timber frame that
was the place marker, permanent set out reference for the circles,
and the vertical axis for the alignment of the height of the walls.
The system seemed to pass the building site test, and even offered a
solution to the handling of the massive quantities of stone that were
required at the various working levels. The permanent portions of the
interior scaffold could be installed progressively, with the
temporary scaffolding coming and going within this main framework
that was supported at its perimeter by the scarcement, and centrally
by the hexagonal frame. Once the dry stone walls had been completed,
the lower temporary props for the scarcement loadings could be
removed.
Could the lower space have been like the byre of the black house, dug out every summer?
This space could also be seen as incorporating the equivalent of the store area of the black house,
with the living space above rather than being parallel to it.
The set out plan
diagram was returned to. Of course! The building process would have
been started with a ceremony. Even today we have the laying of the
foundation stone. One could envisage the marking of place, the axis
mundi, the symbolic centre of the earth – the centre of the hexagon
– with fire and smoke. Australian aboriginals have a smoking
ceremony to cleanse space and place. One could imagine a priest or a
shaman involved in a ceremony celebrating the beginning of this great
enterprise, drawing the hexagon, placating the gods and blessing the land. It
has always seemed that the lack of any spiritual explanation in the
broch studies has been a fundamental weakness. To ancient man, the
whole world was meaningful, symbolic. The building of the broch would
have involved a spiritual celebration. Might the hexagon have
meaning; the numbers 3, 6, 12? The Star of David was never
just a Jewish symbol.#
The meaning of the
beginning would always be the anchor of place; would always be there
for remembrance, defining the connection between man and God: earth
and heaven – the mystery of life itself. The axis mundi was there
as nothing but everything, shaped by the hexagon. The hearth would
become the permanent core, the anchor of life and space, with smoke rising into the heavens creating
the ephemeral physical link between life and its enigmas. Tradition
has always spoken about the importance of remembrance, of the
importance of returning to, of remembering our origins. The
beginnings of the broch would remain as a central reference, not only
throughout its construction period for set out and scaffolding, but
also for the whole life of the place, there for the everyday, for
continued renewal of the spirit and the placation of the Gods.
The efforts to interpret broch functions must to go beyond the search for mere practical purposes.
They need to consider the spiritual context, and its symbolism.
Compare this roof with new 'iron age' roof images below.
Slowly, as one
doodled and thought about the broch, the practicalities of
construction and life became intertwined with things real and tangible; mystical and spiritual. This coherence resonated with reality: we
cannot overlook the mysteries of life and the role they have played, and still play. Architecture has always
involved these; but today we seem to have forgotten this. One only has to flick through Sir Banister Fletcher’s
A History of Architecture to see the thousands of historical
structures rooted in the search for and celebration of meaning.
Brochs could not have been removed from this involvement.
Today’s ponderings
started with the scribbles on the round house plan, so this doodle
was looked at again in order to test the theories revealed by the
other scribbles. How might the idea of the priest/shaman/symbolism
feel with the construction of the round house, the precursor of the
broch?
The scan of Mousa broch showing its axial reference.
The pen was picked
up again and wandered its way around the hearth marked on the plan.
Yes, it would be like this. The point would be marked on the ground
and the hexagon set out, just as we have ground-breaking ceremonies;
the fire lit, the smoke rising as the blessings were chanted and
danced into reality: real place was being marked and blessed to
become the centre, not only of a structure, a permanent marker for
its making, but also for life itself. The idea made wonderful sense
in the simplicity of the round house. From this mystical centre, the
hexagon could rise to become the markers for the circle, an enclosure
both symbolic and real, reconciled by the structure of the roof. The
void of the axis - the untouchable, unspeakable; that which cannot be
named - is there, revealed as a location within the geometrical
forming of the hexagonal frame, the hexagram, and enhanced by the
conical form of the canopy. Daily life would have centred on this
core, the central hearth, from which smoke would rise as the axis,
co-joining man with spirit, even as food was being prepared. Every
activity would relate to this place, just as it would in the broch.
The layering and inter-relationship of logic and dreams in this
theory enrich it and give it substance – poetic credence.
What we call the
beginning is often the end. And to make an end is to make a
beginning. The end is where we start from.
T.S. Eliot
#
SYMBOLISM OF THE HEXAGRAM
As an aside, for a discussion of the symbolism of the hexagram, see:
Photo: Duncan-Enzmann, solstice symbol, Altamira Cave, 16,500 BC
With roots in prehistory, the evolution of this familiar symbol can
be observed
with the following illustration of the winter solstice
symbol, summer solstice symbol, and then combined solstices.
Winter Solstice -Spring Equinox-Summer Solstice-Autumnal
Equinox-Winter Solstice
Illustration from Solomon’s Power Brokers
As with most
symbols, the hexagram gained layers of meaning as it flowed through
time, adapted and adopted by cultures, coming eventually to symbolize
the union of opposites: male and female, fire and water, error and
truth, active and passive, darkness and light, ignorance and wisdom.
*
It is for this reason that it makes no sense to interpret the scarcement only as a support for scaffolding as Brian Smith, (Shetland Museum and Archives), has argued. One would require temporary scaffolding to support the support for temporary scaffolding. The scarcement must have had another purpose. The proposition here is that it supports the permanent internal scaffolding/framing, keeping the perimeter timbers out of the lower ground space that has been zoned as a service space, a 'wet work area,' involving perhaps animals, waste, water.
P.S.
27 APRIL 2019
MORE DOODLES; MORE THOUGHTS
The broch building site: the beginning.
The roof is difficult to tie down - see below.
Note in report below that the smoke filters through the thatch.
The black house relied on this to keep the vermin out of the roof: see -
The wall profiles can easily be set up radially.
They can also be used to set out the concentric circles from the set out of the inner circle.
This process avoids the need to work over any dry stone wall for set outs.
Profiles remote from the elements being set out are still used today.
The central hexagonal frame can be likened to the 3D profile of the broch.
The joists and fire - symbolically central.
The joists can put in piecemeal to act as scaffolding for the work at whatever stage/location.
 |
The roof can be tied down in the round house, (as below), but not to dry stone walls.
Further tie down/bracing/stiffening elements are suggested.
Note that the roof can be erected and maintained from the perimeter, much like the black house, see:
|
The temporary and permanent scaffolding.
Work can proceed on different stages in different locations.
The central hexagonal permanent structure provides the fixed reference point for all elements.
THE NEW 'IRON AGE' ROUND HOUSE
For images of a new
'iron age' round house, see:
The report says that
the round house is '30 metres' in diameter; maybe it means 30 feet? The
roof timbers are said to be from 28 foot lengths. Mousa broch is approximately 20 feet - 6metres - in diameter inside, (50 feet - 15 metres - outside at its base). The images give some idea of the technology and lifestyle of the era as we understand it.
If the rafters are 28 feet long, and the roof is 45 degrees pitch, then the inner diameter is close to 30 feet.
The roof would be approximately the size that would fit Mousa, to sit on its inner twin wall.
Note in the comments above the difficulty in fixing the framing to the dry stone wall.
This round house has no inner structural framing; it is tied down to the outer ring frame.
Traditional round houses do have inner posts.
Brochs would need inner framing not only for a structural profile reference, but also for floor spans.
28 APRIL 2019
Maybe everything to do with brochs is vague and uncertain?
This notice on the door of the Carloway Broch Centre tells visitors that the centre is:
Open
10am to 5pm (or thereabouts)
Monday to Saturday
Admission Free
The scarcement of the Carloway broch is clear, but it is uncertain if it was ever a continuous row of projecting stones, or a series of separate corbels. If it was the latter, these could have carried a segmental bearer for the joists to sit on. It does not change the purpose of the scarcement as the projecting stones still require the mass above to make them stable.
25 February 2020
*
NOTE
19 October 2020
Perhaps peat could have been used. One of the oldest houses on the island of Unst in Shetland, a cottage at Haroldswick, had an internal wall constructed out of peat. Peat is plentiful; it dries to a hard mass; and is a good insulator.
