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Talk and workshop series

The Tracing the Past project at the University of Liverpool, funded by the Arts and Humanities Research Council, has spent the past seven years recording and analysing vaults in England. This talk and workshop series will introduce the project and share some of its key findings in relation to six case study sites in England.

This series is open to the public and free to attend. All are welcome, and Eventbrite links to sign up to talks at individual sites can be accessed below:

Nantwich St Mary’s talk Tuesday 4th May 2021 at 2pm

Nantwich St Mary’s workshop Tuesday 25th May 2021 at 2pm

Chester cathedral talk Tuesday 11th May 2021 at 2pm

Chester cathedral workshop Tuesday 1st June 2021 at 2pm

Lincoln cathedral talk Tuesday 18th May 2021 at 2pm

Lincoln cathedral workshop Tuesday 8th June 2021 at 2pm

Wells cathedral talk Tuesday 15th June 2021 at 2pm

Wells cathedral workshop Tuesday 6th July 2021 at 2pm

Exeter cathedral talk Tuesday 22nd June 2021 at 2pm

Exeter cathedral workshop Tuesday 13th July 2021 at 2pm

Ely cathedral talk Tuesday 29th June 2021 at 2pm

Ely cathedral workshop Tuesday 20th July 2021 at 2pm

MMV Second Symposium

We are delighted to be hosting our second symposium focusing on research into gothic vaults, particularly that aided by digital tools. MMV2 will be an online event hosted by the University of Liverpool, United Kingdom. If you are interested in giving a talk, our call for paper abstracts is open until 30th April 2021.

More information, including the call for papers, can be found here.

Enquiries and abstracts to be addressed

The free event will take place via Zoom on the 19th August 2021 – all welcome! Registration details will be announced closer to the event. Our keynote speakers are Professor Santiago Huerta (Universidad Politécnica de Madrid), Professor José Calvo-López (Universidad Politécnica de Cartagena) and Professor Robert Bork (University of Iowa). We will also share outcomes from our project at the symposium, including our upcoming book, online exhibition and updated website.

Conference organisers: Dr Alex Buchanan and Dr Nick Webb

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


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.

Guest Reviewer Session 1: Norton Priory, Gloucester and Lincoln

The first of our guest reviewer sessions was organised on Wednesday 18th December in 2019.  We asked one of the contributors, Richard Plant, to write a blog post about his experience of the event:

“Writing this from the enforced isolation of April 2020, the meeting held last December at the University of Liverpool seems like an unreal dream of collegiality. There were five of us in the room: Nick Webb and James Hillson from the project, Jenny Alexander from the University of Warwick, Stuart Harrison, Cathedral Archaeologist at York Minster and myself. Alex Buchanan, at home with a heavy cold, occasionally phoned in; something of a foretaste of things to come.

We had been invited to talk about the results of the scanning at Lincoln (in particular the crazy vault and eastern transepts) Norton Priory and the Romanesque parts of the east arm at Gloucester Cathedral.

What was perhaps most surprising about the discussion was how the application of sophisticated digital techniques brought us so often to improvised practices of putting vaults together, and the discussion was much enriched by being shared with such connoisseurs of worked stone as Jenny and Stuart. We worked our way backwards, chronologically, through the buildings. Much of the day was spent on the choir at Lincoln, where the scanning revealed great regularity in the cutting and geometry of the ribs. Yet despite this they also showed that the junction of ribs to walls, and sometimes ribs to ribs had often involved improvisation, with the masons cutting back or cutting in stones in order to make them fit the space. The scanning processes also reveal much about the geometry of the vault webs, which led to discussions of the general relations of ribs to the web (whether the rib is integral or simply sitting below) and also questions about the construction process including the ways and media in which the centering was made.

For Norton and Gloucester we were also dealing with groin vaults and arch construction, but many of the questions relating to their geometry are still complex. The team seemed particularly concerned with variable springing or impost heights, though in Romanesque buildings this is more usual than it seems to be in Gothic ones. Working on bays of irregular shape in Gloucester, both at crypt and choir level, produced many solutions including arches which seemed to have multiple centres. Whilst it might be inferred from this that the irregularities were due to settling, the stonework still appears entirely regular. Painstaking observations of this kind open new avenues of research and reinforces the importance of looking at the stones as well as scanning the geometry, as discussion of the abstractions of geometric schemes often proved to be closely linked to the practicalities of stone cutting. Equally, a better understanding of the geometry helps us to comprehend what the mason was aiming for and what strategies were available for putting their intentions into practice. Even if the answers to many of the questions posed by architectural historians are still not readily solvable, then at least the questions themselves can be posed with greater precision.

All in all it was an enjoyable as well as an informative day. The team are exemplary in their willingness to share and discuss their work, and in their openness to different approaches to their material. The prospects of further investigations are exciting, as will be the debates prompted by the publication of their findings.”


Guest Reviewer Sessions

One of the most exciting parts of any research project are the unexpected questions which arise along the way. Whilst reviewing our scan data or attempting to reconstruct the underlying design processes of medieval vaults, we often encounter gaps in our knowledge about the architecture of a specific site. This can include issues ranging from technical problems, such as the execution of particular features of a building’s stonework, to structural problems, such as the presence or absence of differential settlement across its individual bays, to historical problems, such as the fine details of its chronology. Though these can often be addressed by reading the extensive list of books and articles which have been written about these buildings, sometimes the published literature can only take you so far. In addition, there are many occasions on which the evidence which we have discovered is ambiguous or unclear, supporting to multiple alternative interpretations of a single vault.

With this in mind we have begun to organise a series of guest reviewer sessions, funded by the Research Development Initiative Fund (RDIF) at the University of Liverpool’s School of the Arts. These involve inviting external experts to come to Liverpool to discuss our research and help us answer many of our questions relating to specific sites. Each session focuses on a particular group of buildings, inviting individuals from a range of academic backgrounds including architectural history, art history, archaeology and structural analysis. So far we have run three sessions, the first focusing on our work on Norton Priory, Gloucester and Lincoln, the second on our studies of Chester, Nantwich and Ely and the third on Pershore and Tewkesbury. All of these were extremely useful and opened up many new avenues of discussion which we have continued to pursue over the following months. Though the COVID-19 outbreak has forced us to curtail our plans, we are intending to organise further sessions digitally once things have settled down.

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.


Scanning at Lincoln Cathedral

On 29th to 31st July, we visited Lincoln cathedral to laser scan the interior. The cathedral is something of a magnet for vault enthusiasts, featuring a magnificent range of mainly thirteenth-century examples which were hugely influential throughout Britain – we’ve already scanned some of their offspring at Chester and Ely.

Most famous is the so-called ‘crazy vault’ over St Hugh’s choir, one of the earliest surviving high vaults in the cathedral. There is evidence that the Romanesque cathedral had vaults, specifically in the nave, but we don’t know what they looked like. An eastwards extension of the cathedral, begun in 1193/4 under Bishop Hugh of Avalon (1135-1200), canonised St Hugh of Lincoln in 1220. As part of this project, the new presbytery was vaulted with a design involving an additional rib in an asymmetrical arrangement. This, along with other peculiarities of design and a name, Geoffrey of Noyers, described as ‘constructor of the noble fabric’ in the Greater Life of St Hugh, encouraged Robert Willis to identify the designer as ‘a mad Frenchman’ in a lecture given to the Archaeological Institute in 1848. At a time when Lincoln was venerated as a gem of Early English architecture, this comment was considered heretical, both by Anglophiles and by the French: having been invited to comment on the issue, French architect Viollet-le-Duc pronounced that the architect could not have been French (whose architecture he characterised as wholly rational) but might possibly have come from Normandy. In fact, whatever his ethnicity, Geoffrey was probably unlikely to have been the designer but was probably a clerical administrator.

Although Willis never published his lecture, which is now known only from contemporary journalists’ reports, the ‘mad Frenchman’ epithet entered the historiography, ‘mad’ being transformed along the way into ‘crazy’ and being applied to the vaults as opposed to their designer. A famous article by Paul Frankl cemented this usage and framed the terms of a debate which has continued to the present day.

So what is so ‘crazy’ about the vaults over St Hugh’s choir? Before this, rib vaults were designed either in a quadripartite (divided by diagonal ribs into four parts) or a sexpartite (divided by diagonals and with an additional transverse rib to create six parts) form. We have already scanned quadripartite vaults at Westminster Abbey and there are sexpartite vaults in the transepts of Lincoln cathedral. Both quadripartite and sexpartite vaults have a single central boss per bay of vaulting, marking the junction of the diagonal ribs. As in the transepts and nave at Westminster Abbey, English designers started to use ‘ridge ribs’ to join the bosses longitudinally. Frankl suggested the earliest example of a ridge rib was at the abbey of Montivilliers in Normandy, where the Romanesque church has transepts covered with a form of sexpartite vault. In a number of Norman or Norman-influenced churches, what have been termed ‘semi-sexpartite’ vaults were constructed – these are basically a single quadripartite vaults over two bays, the division between the two bays being marked by a ‘diaphragm arch’. The plan therefore resembles that of a sexpartite vault but the transverse rib which intersects with the diagonals at the centre of the vault bay carries a wall rather than a three-dimensional vault conoid. This type of vault can be seen in the nave of La Trinité, Caen. What we see at Montivilliers is this type of vault turned by 90 degrees, so that the diaphragm arch springs from the end wall of the transept. Once the arch reaches its apex it cannot descend, as if it did, its springing point would be mid-air in the transept. Instead it is therefore continued horizontally to meet the apex of the next transverse arch and then the crossing arch, thus forming a ridge rib. This experiment had no immediate progeny. Other early ridge ribs have been claimed for the Priory of St Mary at Airaines, where they exist alongside diagonal ribs but have a different profile, suggesting a subordinate status and, in a more typical form, in the church at Luchueux. Both these churches are in the Departement of the Somme in northern France. In England, we find early ridge ribs in the north transept chapels of Ripon Minster (probably 1170s), a building which can be related both to local Cistercian architecture and its French sources and to the great cathedral Archbishop Roger was erecting at York (now rebuilt, but elements survive in the crypt). Ridge ribs also flourished in Angevin and Poitevin architecture and were used in the similarly domical high vaults of Münster cathedral in Germany. In all cases, their aesthetic effect is rather different, so even if they do share a common ancestor, they were readily assimilated into a varied range of regional styles.

At Lincoln, St Hugh’s choir has a ridge rib which runs east-west, whose directionality was originally emphasised by painted decoration. Instead of the typical single central boss per vault bay, however, here there are two bosses. This makes the vault ‘eccentric’ (as it was described by John Bilson), meaning that it has no defined central point. Instead of converging on a central boss, the diagonals of the south side of the building converge on the more easterly boss and those on the north side converge on the more westerly. An additional rib from the other side also meets the boss, making each boss mark the conjunction of three ribs in addition to the ridge rib. This additional rib does not mark a change in plane as ribs had previously done and has been described as the first ‘tierceron’, a medieval word usually translated as meaning ‘third rib’. It is as though the diagonal extending from the north-east to the south-west corner of the bay has been split and stretched in two directions along the ridge rib. This sets up an asymmetric, sawtooth rhythm to the vault, further emphasising its longitudinality. Nothing like this had been seen previously in Gothic architecture and, as its form was not replicated elsewhere, it may not have met with contemporary approval. The great transepts at Lincoln reverted to sexpartite vaults and the nave has the first tierceron star vault.

The patterns can also be seen as being formed from pairs of ‘tri-radials’, arrangements of three ribs converging on a single boss. Frankl, a German scholar, was certainly aware that both the use of tri-radials and the asymmetric quality of Lincoln’s vault would form important elements of early fourteenth-century German and Swabian architecture, developed further in the later fourteenth century by Peter Parler at Prague cathedral and forming a key feature of late Gothic. He thus described Lincoln as a proto-late Gothic building, disrupting all standard stylistic chronologies. Whether, and how, the vaults of Lincoln might have influenced Continental Gothic became a topic of much debate – we look forward to the relevant Continental vaults being scanned so that their three-dimensional geometries can be compared with what we find in England.

There are many other current debates about Lincoln, relating to original design intentions, chronologies and extent of repairs after the collapse of the crossing tower in 1237 or 1239. We look forward to seeing what our data can add to these discussions and, indeed, whether it can offer new ways of looking at a building which has puzzled and delighted generations of scholars.

IJoAC Article

Our article investigating the use of digital generative design tools to assist with analysis of Exeter cathedral has now been published in  the International Journal of Architectural Computing.  This article can be viewed here – please contact us for further information. Abstract below:

Medieval masons relied on a ruler and compass to generate designs of increasing complexity in both two and three dimensions. They understood that arcs and lines could be used for proportioning, working with halves, thirds, fifths and so on, rather than specific dimensions. Geometric rules enabled them to create vaulted bays, high up in church and cathedral interiors. In recent years, the influence of digital generative design tools can be seen in our built environment. We will explore generative design to reverse engineer and better understand the design and computational processes that the medieval masons might have employed at our case study site of Exeter Cathedral, England. Our focus is on a run of bays along the nave, which at first appear consistent in their design, yet in reality are subtly different. We will investigate the capacity for changes in the generative process while preserving the overall medieval design concept.

Webb, N., & Buchanan, A. (2019). ‘Digitally aided analysis of medieval vaults in an English cathedral, using generative design tools’, International Journal of Architectural Computing, July 2019.

Scanning at Norwich Cathedral

This week we have been scanning at Norwich cathedral. This is the biggest site we’ve tackled to date – the whole Norman cathedral was covered with lierne vaults in the 15th century and there is also a tierceron vaulted cloister and a 14th-century lierne vault in the so-called Ethelbert Gate into the cathedral precinct.

Like other sites we have previously scanned, including Gloucester cathedral and Tewkesbury abbey, Norwich cathedral remains largely a Romanesque building, originally built as a visible symbol of the Norman Conquest of 1066. The elevations display the massive piers and round-headed arches typical of Romanesque architecture. Although undoubtedly impressive, this style would have looked very old-fashioned by the 14th century, so when the central spire blew down in 1362, damaging the east end of the building, the monks might have seen this as a good opportunity to update their church. The presbytery clerestory (top storey of windows) was rebuilt with Perpendicular tracery and, in the fifteenth century, the whole building was vaulted. The Norman walls had not been intended to carry stone vaults, so we will be interested to explore what effects these might have had on the existing fabric. Moreover, in reverse, the existing bay dimensions would have placed specific requirements on the 15th-century designers, inevitably affecting their artistic freedom.

We selected Norwich as one of our case studies for a number of reasons. Firstly, Professor Robert Willis noted that the cloister vaults showed a number of different 3D forms, despite all following the same 2D plan. Such situations – which we knew existed at Wells cathedral and have also found at Exeter – provide very interesting data for our analysis, revealing the sophistication of medieval design processes. We are therefore very much looking forward to interrogating our scan data once it has been processed. It may also provide further clues for understanding the sequencing of the cloister – the dates at which the different parts were erected – which has long been an interesting puzzle for archaeologists.

In addition, Norwich will provide an interesting comparison with Ely cathedral, as we know from documentary evidence that the same named masons worked on both sites. Members of the Ramsey family worked at Ely and Norwich in the early fourteenth century (as well as at St Stephen’s Chapel in the Palace of Westminster, whose surviving undercroft we have also scanned). Our data may help to identify whether the Ramseys and their teams used the same design methods at different sites and whether their approach was different from our other West Country vaults.

Finally, it has been argued by Frank Woodman that the vault of the Ely Lady Chapel is not 14th-century, as had always been assumed, but dates from the 15th century. He used the high vault at Norwich as a comparison for dating purposes, therefore it will be interesting to see whether laser scan data can be used to support or disprove his theory. The Norwich cathedral lierne vaults are the latest in date that we have scanned and we will be looking to see whether methods had remained constant from the 14th century or whether familiarity with the techniques had enabled improvements.

We are very grateful to all the staff at the cathedral, especially Roland Harris, the Cathedral Archaeologist, for facilitating our visit and making us feel welcome in this beautiful building.

Fire at Notre-Dame

We were shocked and saddened at the scenes from Paris as Notre-Dame Cathedral blazed in the night. Today’s news that the structure of the building seems to be safe has come as a great relief, given its importance both as a symbol and as a monument of Gothic architecture.

The word-famous cathedral was started in around 1160 and the west front dates from the early years of the thirteenth century. Later in that century, the upper storeys were remodelled to introduce a larger clerestory with traceried windows and the transept facades, with their celebrated rose windows, were added. As the mother church of Paris, the building has undergone many alterations and additions over its history, most significantly at the Revolution, when religious images were attacked, and in the nineteenth century, when architect Viollet-le-Duc undertook a major restoration, including the rebuilding of the wooden spire whose dramatic fall became one of the defining moments of the inferno.

Thoughts are already turning to the possibility of reconstruction, to which President Macron has stated his commitment and many millions of euros have been pledged from around the world. This is where research such as ours can be particularly valuable. Thanks to years of surveying and a recent laser survey by the late Professor Andrew Tallon, Notre-Dame is probably one of the best documented medieval buildings in the world. The level of detail provided by a laser scan, consisting of millions of digital points recorded in space to create an exact 3-D digital model, could enable a reconstruction to produce a stone-by-stone replica of a destroyed building. That is not to say that laser scanning would provide all the answers: scans can only record what is visible and cannot identify what is going on under the skin of the building. In particular, wooden roofs of the kind that has been destroyed at Notre-Dame are particularly difficult to document by digital means. Nevertheless, laser scan data would make it relatively easy to interrogate the geometries of the parts of the vaulting that have been lost, in order to accurately recreate their three-dimensional form. The geometries used would thus be based on an understanding of the design methods originally used by the medieval masons. There is a wealth of expertise that the reconstruction team could draw upon to assist in this work, with researchers in Spain, Germany and the United States (as well as us in the UK) all using digital techniques for documentation, interrogation and reconstruction purposes.

Paradoxically, it has often been the case that disasters have helped to enhance our understanding of buildings. The nineteenth-century architectural writer, Robert Willis, who has inspired our research, explored the debris surviving after the collapse of one of the western towers of Canterbury Cathedral and found a stone from the fourteenth-century vault still inscribed with the setting-out lines used by the masons when cutting the vault ribs. He used this as evidence for understanding how their designs were projected into three dimensions. Viollet-le-Duc used his experience of very thoroughgoing restorations to draw conclusions about medieval vaulting techniques, including at Notre-Dame. Some of his theories about the structural behaviour of vaults were challenged by the destruction of some of the northern French cathedrals during the First World War: at times the ribs collapsed, leaving the webbing, supposedly supported by the ribs, still standing without them. It may be hoped that the damages at Notre-Dame might be equally enlightening for further research on early Gothic vaulting, which can then inform the rebuilding.

Victor Hugo, whose 1831 novel Notre-Dame de Paris (more famous in English as The Hunchback of Notre-Dame) called for the restoration of the cathedral, spoke of three agents of change: time, revolution and fashion. To this should be added disaster. He understood all works of architecture as social products, the sediments of ages – as he put it ‘Time is the architect; the nation is the mason’. The future reconstruction of Notre-Dame should be seen in this light. It cannot return Notre-Dame to how it was before the fire, still less to any ‘original’ medieval state. Indeed, even if timber on an adequate scale were available it could be questioned whether there is value in replicating a less visible part of the building whose significance lay in the original timber and medieval carpentry techniques. Nevertheless the reconstruction work of the twenty-first century, which will doubtless use both traditional skills and cutting-edge technologies, will form the latest chapter in the biography of this beautiful building.

Image credit: Antoninnnnn