Tag Archives: Wells Cathedral

Wells Tracing Floor (eCAADe 2020)

In September 2020 we were due to visit Berlin to attend the eCAADe conference, however, COVID-19 shifted proceedings online. Our paper, written by the entire project team, documented and analysed the Medieval tracing floor at Wells cathedral using photogrammetry, reflectance transformation imaging and laser scanning. We presented a summary of our findings via a pre-recorded video and written paper. You can find links to these below, as well the paper abstract. We look forward to attending eCAADe and other conferences in person again once it’s safe to do so.

Documentation and analysis of a medieval tracing floor using photogrammetry, reflectance transformation imaging and laser scanning

Paper link

Video link

Abstract

The fifteenth-century tracing floor at Wells cathedral is an extremely rare survival in European architecture. Located in the roof space above the north porch, this plaster floor was used as a drawing and design tool by medieval masons, the lines and arcs inscribed into its surface enabling them to explore their ideas on a 1:1 scale. Many of these marks are difficult to see with the naked eye and existing studies of its geometry are reliant on manual retracing of its lines. This paper showcases the potential of digital surveying and analytical tools, namely photogrammetry, reflectance transformation imaging (RTI) and laser scanning, to extend our knowledge of the tracing floor and its use in the cathedral. It begins by comparing the recording processes and outputs of all three techniques, followed by a description of the digital retracing of the tracing floor to highlight lines and arcs on the surface. Finally, it compares these with digital surveys of the architecture of the cathedral cloister.

Back to Wells

Last week (11-14th October) we returned to Wells, revisiting our earlier scans and taking the opportunity to scan new areas. In particular, we have been privileged to be allowed to record the ‘tracing floor’, an extraordinarily rare survival of the ‘drawing office’ where the master mason worked out designs full scale by inscribing them on a plaster floor. The tracing floor at Wells is above the north porch of the nave, accessible from the triforium gallery via a spiral staircase in the north transept. Because the surviving examples are in fairly inaccessible places, it is believed that such spaces were probably used for design rather than for cutting stones, however it could be that more accessible multifunctional spaces may not have survived and that the ones we know about were exceptional. There is a larger and more famous example of a tracing floor above the north transept at York Minster, but the Wells example is of particular interest to us because it has been suggested (Pacey) that one area corresponds to the vaults of the cloister.

In recording the tracing floor we have decided to experiment with three different methods. Firstly, we have used photogrammetry, a method we have tested elsewhere, which is based on taking multiple photographs and stitching them together digitally to create an image without the distortion of perspective. We have also scanned the area using our laser scanner on its highest settings, to see how much detail it can record. Finally, we have used an innovative method called ‘RTI’ (Reflectance Transform Imaging). Like photogrammetry, this involves taking multiple images, however, reflective spheres are added to the scene and photographs are taken at intervals around the target’s hemisphere using a flash gun which is set at the same distance from the target in all images. These images are then processed using CHI software, which allows us to re-light the tracing floor from any angle and potentially reveals surface detials that have not previously been seen by eye. Our technicians, Sarah Duffy and JR Peterson, are experts in the use of this method and initial results look very promising in terms of picking up very fine levels of detail. However the method has disadvantages in that it can only currently be used successfully on small areas, which need to have a wide margin around them and which cannot yet be ‘stitched together’ to create a single image. We cannot therefore use RTI on the whole floor, except in individual sections towards the centre of the space. We have therefore sampled two areas that offer potentially interesting data: one which appears to show the springing off a vault and another which has some very fine details not recorded in previous surveys.

We have also taken the opportunity to take laser scans in colour, rather than the black and white we previously used, and to scan some areas we originally omitted, including the chapter house and the cloister. It has also been very helpful to re-examine areas where our data was of insufficiently high quality to answer more archaeological questions. We are very grateful to Jez Fry, the cathedral’s Clerk of Works, for granting us access and facilitating our studies at this most beautiful and fascinating building.

 

British Art Studies Article

Our article investigating the creativity and imagination used to design the choir aisles at Wells cathedral has now been published in ‘British Art Studies’.  This article is free to view here.

Abstract

This paper explores the topics of creativity and imagination in relation to the design and construction of the lierne vaults in the presbytery aisles of Wells Cathedral, erected around 1330. It explores the potential of digital scanning and analysis for forensic investigation of the structure in order to identify the processes involved. Four different processes were employed and we compare those used in the three eastern bays of the north and south aisles. These are shown to share characteristics with the retrochoir but to involve different approaches to 3-D projection and stone-cutting. We conclude that the basic geometry of the vaults was defined in advance of construction, using full-scale drawings worked out on a tracing floor. In both sets of vaults the 3-D geometry continued as a sequence of steps and was derived from measurements ascertained from existing elements (including the drawings) but was not consistent across the two aisles. The processes reveal different priorities, whether for level ridges (north aisle), different choices in terms of rib radii or apex heights, and different sequences of design steps. This demonstrates the potential for experimentation at every stage of construction.

Buchanan, A., & Webb, N. (2017). ‘Creativity in Three Dimensions: An Investigation of the Presbytery Aisles of Wells Cathedral’, British Art Studies, Issue 6.

4th Annual Construction History Conference

On Saturday 8th April, we presented a paper to the 4th Annual Conference of the Construction History Society, which took place in the congenial surroundings of Queens’ College, Cambridge. Robert Willis argued that Queens’ was a perfect example of a medieval college, although we were meeting in the more modern buildings on the other side of the Cam, reached by the famous ‘Mathematical Bridge’, designed by James Essex, who also worked on the lantern of Ely Cathedral which we scanned last year. The medieval fabric of Queens’ includes a beautiful example of a lierne vault in its gate-house – perhaps a future scanning project?

Our paper ‘Tracing Tiercerons: an evaluation of the significant properties of thirteenth and fourteenth-century tierceron vaults in England’, is available here: https://livrepository.liverpool.ac.uk/3006059/.

It was good to catch up with old friends, including Santiago Huerta, and to hear the latest news from our friend David Wendland’s project ‘Design Principles in Late-Gothic Vault Construction’ ). On this occasion, Dr Wendland presented with his collaborator Frédéric Degenève, one of the stonemasons working at Strasbourg Cathedral. Their paper ‘How to order fitting components for looping ribs: Design procedures for the stone members of complex Late Gothic vaults’ was a fascinating reconstruction of the methods used to prepare the voussoirs and bosses required by geometrically complex vaults such as the ‘Hall of Arms’ in the Albrechtsburg Meissen, built in 1521 by Jakob Heilmann. Wendland’s digital analysis of such vaults has demonstrated that all the ribs are formed using circular arcs in three dimensions. In this paper, he provided a convincing explanation of how the essential information could be transferred from the tracing floor to the block of stone using copper templates, ‘baivels’ (or square edges) and a rod to record key dimensions. The proposed method has been tested by and found to meet all the stonemason’s requirements, without any need for stereometric projections.

It was also useful to have the opportunity to meet and discuss our project with others who have also used digital recording methods, including Elizabeth Shotton, from Trinity College, Dublin, who shared her Irish Research Council funded project Minor Harbours, which has used digital methods to identify and analyse changes to the smaller Irish harbours over time.

The full conference programme is available here: http://www.arct.cam.ac.uk/Downloads/fourth-annual-chs-conference-programme.pdf and proceedings are available in print from the Construction History Society.

DAACH Article

Our article investigating the use of digital techniques to analyse the choir aisles at Wells cathedral has now been published in ‘Digital Applications in Archaeology and Cultural Heritage’. This article is free to view until 7th May 2017 through the following link:

https://authors.elsevier.com/a/1UkLO7szebZ9pb

Abstract

Architectural historians have identified Wells cathedral as a key monument in the transition between high and late Gothic, a move in part characterised by the rejection of simple quadripartite or tierceron rib vaults for more complex vaults. Here we will show how digital methods are used to reopen questions of design and construction first posed in 1841 by pioneer architectural historian Robert Willis. Digital laser scanning documents vaults accurately, thereby establishing their geometries to a high degree of certainty and, at Wells, highlighting differences between the choir aisle bays which have previously been treated as a single design. Significantly, we will show how digital techniques can be used to investigate these differences further, using point cloud data as a starting point for analysis rather than an end point. Thus we will demonstrate how modern technologies have the potential to reignite historic debates and transform scholarly enquiries.

Webb, N., & Buchanan, A. (2017). ‘Tracing the past: A digital analysis of Wells cathedral choir aisle vaults’, Digit. Appl. Archaeol. Cult. Herit., 4, March 2017, pp. 19–27.

Review of Modelling Medieval Vaults

We are delighted that our symposium ‘Modelling Medieval Vaults’ was reviewed in the first issue of The Construction Historian (the magazine of the Construction History Society). With the kind permission of the author and editor (David Yeomans), it is reproduced here.

‘The life of a Gothic vault begins with a design, which exists as plan. This has then to be projected into three dimensions, not just to determine the overall geometry but also to enable individual stones of the ribs to be cut to shape so that they fit together. Once assembled the structure of the vault has to be stable and so must transmit the thrusts safely to the supporting walls and buttresses. They will then move in resisting the thrusts and so cracks will develop in the vault ribs and in the vault surfaces that they support, cracks that might seem to be signs of failure but which will have been there for hundreds of years. Sometimes, of course, the building might be destroyed and the vaults will then only survive as rubble, but rubble that might contain clues to the original form of the vault. Each of these stages provides material for different kinds of scholarship and all were represented in this one-day symposium.

There were speakers to cover every stage of the process. Those dealing with design aspects showed clearly the difference between approaches to architectural history and construction history. The former sometimes seemed to involve a special language. I simply cannot imagine what ‘visual space perception in micro and macro cosmological dimensions” could possibly mean, but perhaps it lost something in translation. It was a phrase used by Thomas Bauer in reference to vaulting in Prague with curved non structural ribs, typical of late vaulting in other Northern European countries. I am not sure about their designers ‘contributing to a new space discourse’. The idea that masons devised the elaborate, non-structural pattern of ribs that we were shown to compete with flat decorative ceilings that were coming into fashion seems simple and convincing.

My doubts are how well we can see into the minds of medieval designers. What we do know is that the designers of the more elaborate rib patterns were playing with geometry and that given an accurate survey of the rib pattern it is possible to reconstruct the geometrical process that was used. While Bauer demonstrated the very complex geometry of the vaults in Prague our hosts demonstrated it for the much simpler geometry used in the aisles of the choir at Wells. There vaulting with slight differences in the plans also had differences in section, some being flatter than others. Thus we saw how accurate survey methods now possible might show subtleties that had previously been unrecognized.

Once the geometry had been decided it needed to be marked out on the tracing floor. There is some evidence in the form of putlog holes in the walls that there was a scaffold immediately below the vault, which might have been used as a tracing floor. The masons could then have used plumb lines to the drawing immediately below the vault itself to mark up the stones, much as carpenters use plumb lines to scribe timbers to fit.

Of course the vault has to stand once built although there is often movement over time. Santiago Huerta delighted everyone with a model arch, which demonstrated the formation of cracks within both the ribs and the surfaces of vaults that result from the inevitable movement of supporting walls and buttresses. But while he described the attempts from the eighteenth century onward to understand the behaviour of medieval vaults there was no discussion of how they might have been structurally designed at the time. One speaker’s assertion that the columns of Mallorca cathedral could be as slender as they as because of loading built above the vault ribs simply raises more questions than it answered.

Perhaps the most surprising thing for the outsider was the way in which archaeologists may be able to reconstruct the appearance of collapsed vaults based on material in the rubble. In vaulting with intricate patterns of ribs, stones forming the connections indicate the directions of the connecting ribs and may make it possible to determine the overall pattern.

Much of all this new work on vaulting depends upon modern surveying methods: the use of photogrammetry and laser scanning. One paper compared the use of these two techniques while others described the process of making use of the data from laser scans. Different software packages appear to offer different advantages, or are it disadvantages. RHINO is not it seems a huge horned herbivore but just one of the packages available. There was much discussion of these systems and it was clear that the specialists in these aids needed to be brought in to help the communities of archaeologists or historians.

The last talk addressed what we normally think of as a model because Benjamin Ibarra-Sevilla had used digital printing to construct physical models of the vaults of the churches in Mexico that he had studied. Because the ribs of these are made of separate components they need to be held in pace while being assembled. The students helping with this process were able to gain an appreciation of the delicate balance of forces involved. It seems that what can be learnt about medieval vaults and what can be learnt from tem is far from exhausted. It also seems that from archaeologists to computer specialists there is something in medieval vaulting for everyone.

For anyone wishing to know more about the work being done by The Liverpool School of Architecture on vaulting see www.tracingthepast.org.uk. There is also to be a two-day event at Cambridge to look at the work of Robert Willis at www.robertwillis2016.org.’

We shall be presenting more about our work in a paper at the next conference of the Construction History Society in April 2017. Further details are available here: http://www.constructionhistory.co.uk/wp-content/uploads/2017/02/Fourth-annual-CHS-Conference-Draft-Programme-4.0.pdf.

Scanning at Exeter Cathedral

On Wednesday 30th March we travelled to Devon to collect more survey data from two sites; Exeter Cathedral and Ottery St Mary Church. We spent two days at Exeter and will spend a final day at Ottery.

IMG_2703

Surprisingly, we were joined by a team at Exeter Cathedral who were also there to create a model of it. Whereas we were using digital scanning techniques to produce a highly accurate model of the vaults at Exeter, they were using Lego to create a scale model within the cathedral. You can follow their progress here. We were able to scan the uninterrupted length of high vaults along the nave and choir, the central porch of the screen facade, the crossing, the miniature vaults in the pulpitum and those of the sedilia. These miniature vaults are particularly interesting to us, being documented designs by Thomas of Witney, a mason who also worked at Wells Cathedral, a site we’ve already scanned. At both Exeter and Wells, Witney experimented with the use of liernes, additional decorative ribs, of which Exeter’s are some of the earliest surviving examples. With help from the cathedral archaeologist, John Allan, we were able to identify additional sites to survey, such as the site of the former North walk of the cloister, which was situated between the external buttressing to the south of the nave.

The trip to Exeter was funded by the University of Liverpool’s Interdisciplinary Network Fund.

Funding to scan vaults at Ely Cathedral

Through the Lambarde Fund, we have received a grant from the Society of Antiquaries to scan the lierne vaults at Ely Cathedral, which we intend to carry out towards the end of the summer. The main vaults we will scan and analyse are:

  • Retrochoir (tierceron vaults built under Hugh of Northwold  1234 and 1252, thus, like the Chapter House at Chester, immediately after and influenced by the nave at Lincoln).
  • Octagon (tierceron vaults constructed in timber after the collapse of the Norman crossing in 1322 and showing a similar interest in centralised space as the Wells Lady Chapel).
  • First three bays of presbytery (dated c. 1330 and described by Pevsner as the earliest lierne vault in East Anglia) which also includes an aisle vault in first 3 bays of the north aisle.
  • Lady Chapel – lierne vault of a stellate pattern, built after the Octagon and choir so c.1335-50.
  • Prior Crauden’s Chapel – a vault reconstructed by Willis from the evidence of the springing blocks.

We hope to investigate the decisions taken by Willis when reconstructing the vaults of St Catherine’s Chapel and Prior Crauden’s Chapel in the 1840s.

In addition to forming a case study in its own right, we also hope the  data collected will also allow us to explore differences in vaulting methods between the West Country and South Eastern Decorated styles.

Photo by DAVID ILIFF. License: CC-BY-SA 3.0

A celebration of the life and work of Richard K. Morris

On Saturday 20 March, Alex went to London to attend a study day at the Courtauld Institute, organised by the British Archaeological Association and the Ancient Monuments Society to commemorate Richard K. Morris (1943- 2015), whose work on Decorated architecture in England is very relevant to our project. Richard specialised in the detailed archaeological analysis which is an essential counterpart to our own research and specialised in the study of West Country buildings. His methodology involved the use of mouldings to reconstruct both building chronologies and the careers of individual masons and offered readings of such buildings as Wells Cathedral, Exeter Cathedral, St Augustine’s Abbey at Bristol, Tewkesbury Abbey and Sherborne Abbey, all of which have significant vaults.

The study day offered a varied programme including both new and established scholars. Of particular interest for our project were papers by James Cameron and Peter Draper which discussed medieval architectural drawings: both those which survive (a huge archive of drawings cut on the rocks around an 11th-century temple in Bhojpur, India) and those whose one-time existence might be suggested by the evidence of buildings whose detailed similarities are hard to explain.

Another relevant paper by James Hillson discussed the lierne vault of St Stephen’s Chapel Westminster, which he identifies as a design of the 1340s, rather than the 1290s as most previous interpretations have suggested. The problem is compounded by the loss of the original vaults after the fire at the Palace of Westminster in 1834, although detailed drawings were made and measurements taken by architect Charles Barry and communicated to Robert Willis for his research. If Hillson is right, this redating would mean that the Westminster designs can no longer be identified as the earliest true lierne vault and its relationship with other lierne vaults, such as those at Exeter, Bristol and Wells could be reversed, for the lierne vaults at Wells date from around 1330 and those at Exeter are earlier. The dating of the Bristol vaults remains a matter of controversy, into which Hillson opted not to wade.

Finally, vaults made a virtuoso appearance in a paper by Andrew Budge, who spoke on the chancel at St Mary’s Warwick, which has a tierceron vault with additional ‘skeleton’ ribs. Although Budge drew attention to a number of English examples of such vaulting, at St Augustine’s Bristol, the pulpita (screens) of St David’s Cathedral and  Southwell Minster, the Easter Sepulchre of Lincoln Cathedral, stairway vaults at Thornton Abbey and Wells Cathedral and around the apse of Peterborough Cathedral, he also pointed out their existence in the so-called ‘tonsura’ at Magdeburg Cathedral. It was suggested that Thomas Beauchamp, 11th Earl of Warwick (1313-1369), who was buried in the chancel, might have visited Magdeburg en route to or from crusading activities and that the inclusion of skeleton vaults above his tomb might therefore represent an aspect of a ‘biography’ in stone. This of course offers some of the same problems about knowledge transfer as had already been addressed by James Cameron in relation to near-duplicate designs for sedilia. Whatever their meaning, these vaults amply demonstrate the exuberant inventiveness of architects of the Decorated period, whose methods we are seeking to explore.

Overall the day offered a wonderful opportunity to pay tribute to the work and influence of a kind and generous scholar with exemplary commitment both to his subject and to future scholarship.

 

 

 

Map of British Medieval Vaults

On the vaults page we have started a map which locates significant Medieval vaults in the British Isles.  So far we have included sites already visited and scanned as well as sites we intend to visit. We have also located some initial vaults of interest which may be documented as the project progresses. Please contact us with suggestions of sites to add!