Saturday 30 August 2014

Stonehenge rings within rings

Parchmark plan from English Heritage as published on http://www.bbc.co.uk/news/uk-england-wiltshire-28967538 - Colour enhanced for clarity. Click any to enlarge.


In July 2013 various parchmarks were showing up at Stonehenge - as reported on this blog and professionally at http://antiquity.ac.uk/ant/088/ant0880733.htm The most noticeable were the stone hole marks between Stones 16 and 21.

But the Z and Y holes were also showing up well. Walking round them I noticed there seemed to be extra marks that were also in a circular pattern. They were jokingly called the Daw Holes as it seemed they were a product of my overheated imagination. But over the next week as the weather changed some became more noticeable and then they faded. As they were fading Mark Bowden and Sharon Souter from EH GPS mapped them as best we could. Some were more certain than others, some were quite doubtful but until the next spell of similar weather the plan above is as accurate as we will get of the phenomenon. 

It was noticeable that the Z and Y holes that had been excavated and those that hadn't appeared the same, and that the other parch marks were very similar to the known holes.

I realised that the marks might have more modern causes, the most obvious being the Fire Garden for the Olympics, but they didn't seem to coincide with any installations so I am certain that was not a cause.

One reason for some of the marks may be the larch poles used to prop the stones up in late Victorian times. Sharpe's aerial photograph shows them well and can be overlain to some degree of accuracy onto the plan (As stones were leaning it is not completely accurate.) 




Apart from the poles for Stone 7 they don't noticeably line up with the marks but I would treat any marks near where the poles were installed with scepticism.

But this still leaves a lot of unexplained marks forming a rough ring equidistant between the Z and Y holes.

The wobble in the ring of Y holes (outer ring of marks) in the south east corner might be explained by reassigning Y6, Y7 and Y8 to the middle "Daw hole" ring and noting the faint marks further out as possible Y holes that were missed by Hawley.


What the marks show and from when is a new mystery of Stonehenge.

The conclusion of the Antiquity paper is: “The new discoveries do tentatively allow further consideration of the multicircuit post settings envisaged by Gibson (1998: 41-44) and comparison with Woodhenge and the Sanctuary as well as Stanton Drew (David et al. 2004) but in the absence of dating evidence this remains speculative. The more diffuse marks around the periphery of the site might offer support for Pitts’ (1981) suggestion of an outer ring of stones. However, again, more research is needed to clarify this issue. This emphasises the potential for new discoveries about Stonehenge (one of the most widely researched monuments in the world) through non-invasive as well as invasive techniques.”


Stonehenge Complete Circle Evidence

BBC news story:

Stonehenge 'complete circle' evidence found
....Historians have long debated whether Stonehenge was a full or incomplete circle, with some arguing a lack of stones in the south-west quadrant is proof it was never complete.

A scientific paper which adds weight to the "complete" theory has been published in the latest issue of the journal Antiquity.

The parch marks - areas where the grass does not grow as strongly as in other areas during hot, dry weather - were first noticed in July last year.

Susan Greaney, from English Heritage, said the discovery seemed to indicate the positions of missing stones. "If these stone holes actually held upright stones then we've got a complete circle," she said. "It's really significant, and it shows us just how much we still have to learn about Stonehenge.......



Wednesday 27 August 2014

Stonehenge - More Circles?

Win Scutt's ArchNews  @Archaeology_ws


https://twitter.com/Archaeology_ws/status/504676435823710208

Stonehenge: circle of parchmarks identified outside sarsens between Y and Z holes @AntiquityJ bit.ly/1mSDIJC



Win has spotted the surprise finding of the Antiquity parchmark paper - that maybe there are more circles at Stonehenge...

The conclusion of the paper is: “The new discoveries do tentatively allow further consideration of the multicircuit post settings envisaged by Gibson (1998: 41-44) and comparison with Woodhenge and the Sanctuary as well as Stanton Drew (David et al. 2004) but in the absence of dating evidence this remains speculative. The more diffuse marks around the periphery of the site might offer support for Pitts’ (1981) suggestion of an outer ring of stones. However, again, more research is needed to clarify this issue. This emphasises the potential for new discoveries about Stonehenge (one of the most widely researched monuments in the world) through non-invasive as well as invasive techniques.”

I can't share the plans yet so here is one of some other circles instead...


Click to enlarge - for more on Stanton Drew see 







Antiquity article on Stonehenge parchmarks




Antiquity Issue 341 - September 2014

Simon Banton, Mark Bowden, Tim Daw, Damian Grady and Sharon Soutar

Parchmarks at Stonehenge, July 2013.... Volume: 88 Number: 341 Page: 733–739

Despite being one of the most intensively explored prehistoric monuments in western Europe, Stonehenge continues to hold surprises. The principal elements of the complex are well known: the outer bank and ditch, the sarsen circle capped by lintels, the smaller bluestone settings and the massive central trilithons. They represent the final phase of Stonehenge, the end product of a complicated sequence that is steadily being refined (most recently in Darvill et al. ‘Stonehenge remodelled’, Antiquity 86 (2012): 1021–40). Yet Stonehenge in its present form is incomplete—some of the expected stones are missing—and it has sometimes been suggested that it was never complete; that the sarsen circle, for example, was only ever finished on the north-eastern side, facing the main approach along the Avenue. A chance appearance of parchmarks, however, provides more evidence.

©2014 © Antiquity Publications Ltd.

Tuesday 26 August 2014

Vince Gaffney's Liturgical Routes

Vincent Gaffney's research on the Hidden Landscape of Stonehenge is dominating the Stonehenge news at the moment. Lots of impressive stuff but I noticed one phrase kept coming up:

Vince Gaffney, one of the lead researchers is quoted as saying: “The point I think we’re coming to is that increasingly we can see the area around Stonehenge as providing extensive evidence for complex liturgical movement—which we can now understand, largely because we know where things are.”

The break in the Cursus to the north of Stonehenge seems to be one of these liturgical routes.  This theme is one that Gaffney has covered before. His co-authored book Stonehenge Landscapes: Journeys Through Real and Imagined Worlds, published in 2000, examines the same idea:

To quote:
The importance of paths and tracks within the formation of past landscapes has been much discussed within the recent literature (Edmonds 1999, Ingold 1993). It seems clear from this debate thai paths are not passive or simply functional landscape features. Paths and tracks make statements about signifìcant features within a landscape. and ultimately have a formative role in that they begin to guide movement. In highly charged landscapes, like that around Stonehenge, paths and tracks may have a liturgical role. They may guide the observer through a directed sequence of movements and spatial relationships, perhaps emphasising links with past landscapes, or relationships between groups, and indirectly restating the importance of social or power relationships through repetitive movement in a prescribed manner. Despite the importance of movement within a landscape archaeologists only occasionally have access to this information, and in the past have rarely attempted their reconstruction at a landscape level. Only in exceptional circumstances such as the preserved tracks on the Somerset Levels can we physically experience such paths, but it is intriguing to note that, however interpreted, these paths may also have had a ritual aspect through the deposition of specific objects including flint or figurines within the body of the track (Coles and Coles 1986).

This pessimistic statement is not entirely true for Stonehenge. Here there are a number of tracks defined formally within the landscape. The cursus monuments and the Avenue appear to function as processional ways and, as such, can clearly be interpreted as tracks of a highly specific type..... 

I eagerly await his new results, due 9th Sept I believe, I would like liturgical routes to have evidence of erosion or depositions along them, all we can do is wait to see.

A timeline of the Hidden Landscape Project is here


UPDATE - I am reminded in the comments of a previous Press Release from 2011.

Discoveries provide evidence of a celestial procession at Stonehenge

Saturday 23 August 2014

Detailed analysis of Stonehenge Bluestones and the Altar Stone by Rob Ixer

Two papers to download for those seriously interested in the stones of Stonehenge:

A detailed re-examination of the petrography of the Altar Stone and other non-sarsen sandstones from Stonehenge as a guide to their provenance by Robert Ixer

 DETAILED PROVENANCING OF THE STONEHENGE DOLERITES USING REFLECTED LIGHT PETROGRAPHY -A RETURN TO THE LIGHT by Robert Ixer

The Stonehenge Hidden Landscapes Project by Vincent Gaffney Online

Lot of chatter online about a new film coming this autumn revealing new discoveries in the landscape at Stonehenge - http://www.smithsonianmag.com/history/what-lies-beneath-Stonehenge-180952437/ - http://www.dailymail.co.uk/sciencetech/article-2731994/Why-Stonehenge-built-Discovery-15-new-monuments-suggests-answer-lie-BENEATH-ground.html - much of it is based on Vincent Gaffney et al's research.

(The research has continued since this paper was released but it seems to cover all the "new" discoveries that are being reported.)

The Stonehenge Hidden Landscapes Project by 


Click to enlarge - but follow link below to get full paper.

Available online at :


Gaffney, C., Gaffney, V., Neubauer, W., Baldwin, E., Chapman, H., Garwood, P., Moulden, H., Sparrow, T., Bates, R., Löcker, K., Hinterleitner, A., Trinks, I., Nau, E., Zitz, T., Floery, S., Verhoeven, G. and Doneus, M. (2012), The Stonehenge Hidden Landscapes Project. Archaeol. Prospect., 19: 147–155. doi: 10.1002/arp.1422
wileyonlinelibrary.com/journal/arp.

The Missing Stones - Did they look like this?

Pleased to see a reconstruction of the missing stones 17, 18, and 19 and 20 will be featuring in a new film about Stonehenge. 


Frames from Stonehenge Empire show stones whose locations were determined only in 2013. (© October Films for Smithsonian Channel )

Stonehenge Empire

Stonehenge revealed

October Films has gained exclusive access to the international team of scientists conducting the most exciting and far reaching archaeological project at Stonehenge since the 1960’s.
The series will combine new archaeological evidence from the international survey, drama reconstructions and state-of-the art CGI to produce the most complete and interconnected picture of the how the whole site looked in its heyday; revealing Stonehenge to be a Neolithic Valley of the Kings.

Planned transmission is for Autumn 2014
Broadcaster
BBC Two, Canadian Broadcasting Corporation, Smithsonian Channel, France 5, ORF Austria and ZDF Germany

Tuesday 19 August 2014

Stonehenge Landscape Survey

Proceedings of the Prehistoric Society





Analytical Surveys of Stonehenge and its Immediate Environs, 2009–2013: Part 1 – the Landscape and Earthworks



By DAVID FIELD, NEIL LINFORD, MARTYN BARBER, HUGO ANDERSON-WHYMARK, MARK BOWDEN,
PETER TOPPING and PAUL LINFORD
With contributions by
MARCUS ABBOTT, PAUL BRYAN, DEBORAH CUNLIFFE, CAROLINE HARDIE, LOUISE MARTIN, ANDY PAYNE, TREVOR PEARSON, FIONA SMALL, NICKY SMITH, SHARON SOUTAR and HELEN WINTON


Integrated non-invasive survey in the Stonehenge ‘triangle’, Amesbury, Wiltshire, has highlighted a number of features that have a significant bearing on the interpretation of the site. Among them are periglacial and natural topographical structures, including a chalk mound that may have influenced site development. Some geophysical anomalies are similar to the post-holes in the car park of known Mesolithic date, while others beneath the barrows to the west may point to activity contemporary with Stonehenge itself. Evidence that the ‘North Barrow’ may be earlier in the accepted sequence is presented and the difference between the eastern and western parts of the enclosure ditch highlighted, while new data relating to the Y and Z Holes and to the presence of internal banks that mirror their respective circuits is also outlined.

Conclusions:

Multi-disciplinary, non-invasive, analytical survey techniques
have produced a considerable amount of fresh
data relating to the chronological depth and spatial
relationship of sites and features across the ‘triangle’
which provides a broader context for the pivotal
monument of Stonehenge. The latter can now be seen as
part of a suite of immediately adjacent ceremonial and
burial monuments, the earliest of which may be a small
formerly unrecognised Cranborne Chase-style long
barrow, while several others with henge-like affinities
might be expected to fit within a 3rd millennium BC
cultural spectrum and to have been contemporary with
one or more of the Stonehenge phases.....On the ground
the presence of subtle earthworks at Stonehenge has
an important bearing on the interpretation of the
structural phasing of the site, for while some features
attest to the attrition of the historic period, others are
undoubtedly ancient and add new details relating to the
enclosure ditch, Y and Z Holes, the possibility that the
‘North Barrow’ is an earlier feature, and introduce a
previously unobserved mound amongst the stones. Laser
scanning of the ground surface has provided a detailed
record of subtle undulations that depict the site’s
chronological and cultural biography. Accompanying
these data are the high-resolution GPR results collected
over the Stonehenge monument which successfully
revealed a series of anomalies to complement both
existing geophysical data sets and the earthwork
surveys. Deeper lying geological anomalies, possibly
flint seams or layers of marl within the chalk, have also
been revealed beneath the site although it is unclear
whether these might have once had surface expression.....



Lots of fascinating stuff - get a copy.

Authenticity in conservation is an outmoded sacred cow.

http://www.boydellandbrewer.com/store/viewItem.asp?idProduct=14465

Conserving and Managing Ancient Monuments

Heritage, Democracy, and Inclusion

Keith Emerick


The origins and use of conservation principles and practice from the nineteenth century to the present day are charted in this volume. Written from the perspective of a practitioner, it examines the manner in which a single, dominant mode of conservation, which held sway for many decades, is now coming under pressure from a different and more democratic heritage management practice, favouring diversity, inclusion and difference. 
The author blends case studies from Ireland, Cyprus and England with examples from current practice, community heritage initiatives and political policy, highlighting the development and use of international charters and conventions. 
Central to the main argument of the book is that the sacred cows of conservation - antiquity, fabric and authenticity - have outlived their usefulness and need to be rethought. 

Dr Keith Emerick is an English Heritage Inspector of Ancient Monuments in York and North Yorkshire; he is also a Research Associate at the University of York.


I think I prefer "antiquity, fabric and authenticity" to "democratic heritage management practice, favouring diversity, inclusion and difference"; but then I'm old fashioned, and can't afford the £60 to buy the book to be converted.

Monday 18 August 2014

Under the Stonehenge Landscape


Unveiling the prehistoric landscape at Stonehenge through multi-receiver EMI 
Philippe De Smedt, Marc Van Meirvenne, Timothy Saey, Eamonn Baldwin, Chris Gaffney, Vince Gaffney

Archaeological research at Stonehenge (UK) is increasingly aimed at understanding the dynamic of the wider archaeological landscape. Through the application of state-of-the-art geophysical techniques,unprecedented insight is being gathered into the buried archaeological features of the area. However,applied survey techniques have rarely targeted natural soil variation, and the detailed knowledge of the palaeotopography is consequently less complete. In addition, metallic topsoil debris, scattered over different parts of the Stonehenge landscape, often impacts the interpretation of geophysical datasets. The research presented here demonstrates how a single multi-receiver electromagnetic induction (EMI)survey, conducted over a 22 ha area within the Stonehenge landscape, offers detailed insight into natural and anthropogenic soil variation at Stonehenge. The soil variations that were detected through recording the electrical and magnetic soil variability, shed light on the genesis of the landscape, and allow for a better definition of potential palaeoenvironmental and archaeological sampling locations. Based on the multi-layered dataset, a procedure was developed to remove the influence of topsoil metal from the survey data, which enabled a more straightforward identification of the detected archaeology. The results provide a robust basis for further geoarchaeological research, while potential to differentiate between modern soil disturbances and the underlying sub-surface variations can help in solving conservation and management issues. Through expanding this approach over the wider area, we aim at a fuller under-standing of the human-landscape interactions that have shaped the Stonehenge landscape.
© 2014 Elsevier Ltd. All rights reserved.

Some nice results, showing up a couple of hengiforms for instance.



Sunday 17 August 2014

Songs of the Stones - The acoustics of Stonehenge - pseudoscience?

Songs of the Stones: An Investigation into the Acoustic Culture of Stonehenge 
Dr. Rupert Till - University of Huddersfield, UK.  Journal of the International Association for the Study of Popular Music   doi:10.5429/2079-3871(2010)v1i2.10en

 "concludes that the sonic features of Stonehenge were noticeable and significant, and that it is likely that they were a part of the ritual culture of the site."


Now acoustic expert D.N.Thomas has hit back -

Pseudo science in British archaeoacoustics: Rupert Till's interpretation of the perception of sound. 

which "suggests that Till's approach is pseudo scientific approach and likely to
lead to erroneous conclusions and misinterpretation".












Pseudo science in British archaeoacoustics: Rupert Till's interpretation of the perception of sound.
D.N.Thomas

'
This essay addresses Rupert Till's interpretation of the human perception of sound in the
paper 'Songs of the Stones: An Investigation into the acoustic culture of Stonehenge' (Till
2010). The author suggests that Till's approach is pseudo scientific and likely to lead to
erroneous conclusions and misinterpretation. Set within the context of an acoustical
analysis of Stonehenge, Till presents his interpretation of the way human beings perceive
audible and inaudible sound in a section titled 'Perception of sound at different
frequencies'. He divides sound into 4 types and outlines the idea as follows,
' From 1-14 hz one perceives frequencies as rhythms, whether a drum pattern or the
rhythmic sound of a train. These frequencies are normally described as a number of beats
per minute or b.p.m. For example 2 Hz equates to two beats per second, or 120 beats per
minute, 3Hz is three oscillations per second, or 180 bpm. Above 3 Hz one typically
subdivides the rhythm, perceiving 4Hz as the same tempo as 2 Hz; as the same speed,
but with a doubled pulse, as 120 bpm with a quaver (eighth note) pulse ... ' (Till 2010, pg
8 ).
Till's ideas are based on his understanding that
' Terms like frequency (Hz) and period (seconds) are useful in different situations, and are
perceived differently, even though they are essentially the same thing' (Till 2010, pg 9).
unfortunately there are serious problems with this interpretation of the term frequency. If
sound is a perception created by vibratory motion of the hearing mechanism and
Sources of sound can be described by displacement time curves ' (Campbell and Greated
1994),
sound analysis indicates that rhythmic frequency (repetition and pulse) measured in hertz
is not comparable to the frequency of a sound wave (wave length and amplitude) also
measured in hertz. A repeated sonic event occurring twice per second creates a periodic
rhythm with a frequency of 2 (hz) but each sonic event results in the creation of a distinct
set of sound waves ranging in frequency from 20-20,000 hz (depending on the nature of
the sound source). It follows that Till's interpretation of the term 'frequency' conflates and
confuses the meaning of that term. The terms 'sound frequency ' and ' rhythm frequency'
are not perceived differently but have distinct meanings. Whilst both rhythm frequency
and sound wave frequency share the common descriptor (Hz), the frequencies of sound
waves cannot be construed as being similar to the frequency of a perceived rhythm.
Professor Rupert Braithwaite warns us of the dangers of the misinterpretation of scientific
concepts,
' Pseudosciences never produce new insightful knowledge, they are circular and static.
Any research that is carried out serves only to establish the pre- existing beliefs or
agendas of the individuals (committing the confirmation - bias fallacy). Here, only certain
forms of information count as knowledge ' ...
Till goes further, his alternative descriptor for the term infrasound as 'Time' leads to a
method in which a number of scientific concepts are confused, conflated and replaced by
a single unworkable approach,
' it is possible to hear notes lower than 20 hz they have to be increasingly loud in order to
hear them... Periodic rhythmic vibrations with frequencies below 20 hz such as a series of
short impulses or clicks, can also be heard ...10 hz can be described as 150 bpm with a
semi quaver pulses or as a time period of 0.1 s (Till 2010 pg 7),
Infrasound (0-20 hz) is not related to or associated with the creation of 'a series of short
impulses or clicks' . Sounds with frequencies below 20 hz are described as inaudible
frequencies because laboratory tests suggest that this is a reasonable conclusion. To think
of infrasound as anything like a rhythmic pulse or beat is highly misleading ( a 2 hz sound
wave is 171 metres long and 42 metres high). Till's approach leads to the conclusion that
Stonehenge has a 'resonant frequency ' of 10 hz, possibly linked to alpha wave patterns.
'Stonehenge could be made to resonate...much like blowing over the top of a bottle to
make it hoot, or like running one's finger around the top of a glass or hitting the skin of a
drum... This would work by making the air in the space vibrate at its fundamental resonant
frequency. Measurements of the diameter of Stonehenge told us that this frequency would
be about 10 hz. ...10 hz is a frequency that when detected in the brain is described as an
alpha wave pattern... ' (Till 2010 pg 7).
Braithwaite warns us of the use and over-reliance on metaphor as an argument in and of
itself. In the paragraph above Till compares the space within a stone circle to that within a
bottle, a glass, and the shell of a drum. The reader is expected to accept understand and
link these metaphors using his peculiar interpretation of the term frequency. Computation
of any fundamental resonant frequency using axial, tangential and oblique mode
calculations is impossible at Stonehenge (the stone 'circle' is open to the sky) such
computation requires an enclosed space (four walls, floor and ceiling). The presentation of
a mathematical model for predicting resonant frequencies (Till 2010 Figure 1 by Faziendi)
at Stonehenge based on the geometry of an open ended cylindrical tube is unhelpful.
Stonehege is not circular in shape. If Stonehenge was an open ended cylindrical tube we
might expect its resonant frequency to be 45 hz but Stonehenge is not an open ended
cylindrical tube.
' At the centre of a circular building... a sound hits and reflects straight back from the
wall ... this would produce a prominent echo and reverberation from the combination of a
number of 'echoes', or reflections …In a circular space.... The overall effect would be
echoes (in a large space) or resonance/ reverberation ' (Till 2010).
Inside a circular building the shape of the walls will be one of many factors (room
dimensions, air gaps, internal structures, surface and building materials) which may
influence the acoustic characteristics of the space. In prehistoric circular dry stone
constructions, bee hive cells, Scottish round houses and circular brochs, sounds do not 'hit
and reflect straight back from the wall' . Inside circular dry stone structures sounds of at
least 1000 hz and upwards are not reflected but scattered, diffused by the edge surfaces
and gaps between the stones. Dry stone construction fosters an acoustically 'dry '
environment with few reflections and short reverberation times (Thomas 2007).
' Pseudoscience presents itself as scientific in nature... the problem here is not only the
false interpretations, but the claims that these interpretations are factual in a scientific
sense. It is this latter inherent claim of scientific credibility and authority which makes the
toxic effect of pseudo thinking so potent. To the uncritical and ill-informed, a pseudo
scientific claim could appear perfectly reasonable' (Braithwaite 2006).


Biography
Braithwaite and Townsend. 2006. Good Vibrations: The Case for a Specific Effect of
Infrasound in Instances of Anomalous Experience has Yet to be Empirically Demonstrated
{Behavioural Brain Sciences Centre, School of Psychology, University of Birmingham, UK,
B15, 2TT}http://birmingham.academia.edu/DrJasonJBraithwaite
Braithwaite J. 2006 Seven Fallacies of Thought and Reason: Common Errors in
Reasoning and Argument from Pseudoscience {Behavioural Brain Sciences Centre,
School of Psychology, University of Birmingham, UK, B15, 2TT}
http://birmingham.academia.edu/DrJasonJBraithwaite
Browne, M. N., & Keeley, S. M. (2003) Asking the right questions. A guide to critical
thinking (7th Edition), New Jersey. Pearson Prentice Hall.
Campbell M. and Greated C. 1994 The Musician's Guide to Acoustics. Oxford. Publisher.
Oxford University Press. ISBN 019159167X, 9780191591679
Carroll, R. T. (2005) Becoming a critical thinker. A guide for the new millennium (2nd Ed).
Boston. Pearson Custom Publishing.
Carroll, R. T. (2003) The skeptics dictionary. A collection of strange beliefs, amusing
deceptions and dangerous delusions. New Jersey. John Wiley & Sons,
Gardner, M. (1957) Fads and fallacies in the name of science. New York. Dover
Publications, Inc. Oxford 2010.
http://www.oxforddictionaries.com/definition/english/conflate
Till R 2010 'Songs of the Stones : An Investigation into the acoustic culture of Stonehenge'.
http://eprints.hud.ac.uk/13248/1/TillSongs308-2422-1-PB.pdfBraithwaite, J.J. (2006)
Lett, J (1990) A field guide to critical thinking. Skeptical Inquirer (14), 2, 1- 9.
Shermer, M. (2002) Why people believe weird things. New York. Henry Holt & Company.
Thouless., R. H. (1968) Straight and crooked thinking. London, Pan Books.
Thomas 2007. An Investigation of Aural Space inside Mousa Broch by Observation and
Analysis of Sound and Light.
http://intarch.ac.uk/journal/issue30/thomas_index.html
Whyte, J. (2005) Crimes against logic. New York. McGraw-Hill.

Friday 8 August 2014

How to construct a level sarsen circle with boning rods.

The stonemason who is building the Long Barrow at All Cannings explained to me how easy it would be to set out the sarsen circle and get it level.

Before laser levels, and still widely in use, on building sites boning rods were used. These are the T shaped wooden stakes you will have seen on the edges of sites.

They don't actually need a T shape, though it helps. Just posts that all have an equal length marked from one end work.

So make eight five foot long straight posts with a pointed end and a flat end. Lie them side by side and mark all of them at four feet from the flat end with a line.

Now on a wet autumnal day decide where you want the centre of your circle to be. Scoop out a shallow depression, six feet in diameter but only six inches deep or so and puddle the clay soil by dancing around on it. You may find a greasy auroc skin helps line the pool. If it doesn't rain enough fill the pool with water.

Around the edge of the pool space your eight posts equally and bang them into the ground until the marked line is level with the water. You now have a ring of posts whose tops are level.

Looking across from post to post it is then easy to set up other posts so their tops are also level.



And then you can decide that the top of your sarsen uprights should be so many feet above that level, and you can measure down into the excavations from your level to get the depth of the hole right for the length of the sarsen you have to hand.

As he says, simples. But I hadn't had it explained to me before so it had never occurred to me that that was how it could be done..

More on boning rods at http://www.pavingexpert.com/setout03.html




Tuesday 5 August 2014

Edgerton's Stonehenge Pictures

Harold "Doc" Edgerton is probably most famous for his milk drop photo:


But during the last European Unpleasantness (1939-1945) he was involved in strobe pictures and aerial reconnaissance. And luckily for us Stonehenge was a target...



(better quality)



And his most famous


More at webmuseum.mit.edu/detail.php?t=subjects&type=all&f=&s=stonehenge&record=0