Posts Tagged ‘ experimental archaeology ’

ARkit and Archaeology – Hougoumont Farm, Waterloo

For the last 3 years I have had the absolute privilege of being one of the archaeological directors of the current excavations of the battlefield of Waterloo. As part of the incredible project Waterloo Uncovered (http://www.waterloouncovered.com) – we have been taking wounded serving and veteran soldiers, students and professional archaeologists  to the battlefield to conduct the first major systematic excavation of parts of the battlefield that shaped the history of Europe in 1815.

We only have two weeks in the field each year, which means there is not a lot of time to doing anything but excavate, record and backfill (see the dig diaries and videos of all we got up to here). However, this year I managed to find the final afternoon to play with the new Apple ARkit and see what potential there is for archaeological sites.

The short answer is that there is a lot of potential! I have discussed Augmented Reality and archaeology to the nth degree on this blog and in other places (see here for a round-up) – but with the beta release of ARkit as an integrated part in iOS11, Apple may have provided the key to making AR more accessible and easier to deploy. I tried out two experiments using some of the data we have accrued over the excavations. Sadly I didn’t have any time to finesse the apps – but hopefully they should give a hint of what could be done given more time and money  (ahem, any prospective post-doc funders – my contact details are on the right).

Exploring the lost gardens of Hougoumont

The first video shows a very early experiment in visualising the lost gardens of Hougoumont. The farm and gardens at Hougoumont were famously defended by the Allied forces during the battle of Waterloo (18th June 1815). Hougoumont at the time was rather fancy, with a chateau building, large farms buildings and also a formal walled garden, laid out in the Flemish style. One of the participants this year, WO2 Rachel Willis, is currently in the process of leaving the army and studying horticulture at the Royal Horticultural Society. She was very excited to look at the garden and to see if it was possible to recreate the layout – and perhaps even at some point start replanting the garden. To that end she launched herself into the written accounts and contemporary drawings of Hougoumont and we visited a local garden that was set out in a similar fashion. Rachel is in the process of colouring and drawing a series of Charlie Dimmock style renditions of the garden plans for us to work from – but more on that in the future.

Similar gardens at Gaasbeek Castle

Extract from Wm. Siborne’s survey of the gardens at Hougoumont

As a very first stab at seeing what we might be able to do in the future, I quickly loaded up one of Rachel’s first sketches into Unity and put a few bushes and a covered walkway in. I then did some ARkit magic mainly by following tutorials here, here, and here. Bear in mind that at the time of writing, ARkit is in beta testing, which means you need to install Xcode Beta, sign up for and install the iOS 11 beta program for the iPhone and also run the latest beta version of Unity. It is firmly at the bleeding edge and not for the faint-hearted! However, those tutorial links should get you through fine and we should only have to wait a few months and it will be publicly released.  The results of the garden experiment are below:

As can be seen, the ARkit makes it very simple to place objects directly into the landscape OUTSIDE – something that has previously only really been possible reliably using a marker-based AR plugin (such as Vuforia). Being able to reliably place AR objects outside (in bright sunshine) has been somewhat of a holy grail for archaeologists, as unsurprisingly we often work outside.  I decided to use a ‘portal’ approach to display the AR content, as I think for the time being it gives the impression of looking through into the past – and gives an understandable frame to the AR content. More practically, it also means it is harder to see the fudged edges where the AR content doesn’t quite line up with the real world! It needs a lot of work to tidy up and make more pretty, but not bad for the first attempt – and the potential for using this system for archaeological reconstructions goes without saying! Of course as it is native in iOS and there is a Unity plugin, it will fit nicely with the smell and sound aspects of the embodied GIS – see the garden, hear the bees and smell the flowers!

Visualising Old Excavation Trenches

Another problem we archaeologists have is that it is very dangerous to leave big holes open all over the place, especially in places frequented by tourists and the public like Hougoumont. However, ARkit might be able to help us out there. This video shows this year’s backfilled trenches at Hougoumont (very neatly done, but you can just still see the slightly darker patches of the re-laid wood chip).

Using the same idea of the portal into the garden, I have overlaid the 3D model one of our previous trenches in its correct geographic location and scale, allowing you to virtually re-excavate the trench and see the foundations of the buildings underneath, along with a culverted drain that we found in 2016. It lines up very well with the rest of the buildings in the courtyard and will certainly help with understanding the further foundation remains we uncovered in 2017. Again, it needs texturing, cleaning and bit of lighting, but this has massive potential as a tool for archaeologists in the field, as we can now overlay any type of geolocated information into the real world. This might be geophysical data, find scatter plots or, as I have shown, 3D models of the trenches themselves.

These are just very initial experiments, but I for one am looking forward to seeing where this all goes. Watch this space!

 

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Learning by Doing – Archaeometallurgy

This post will be a little off my normal topics, in that there will no augmented reality and no computers (although I did make some nice 3D models that I’ll link to later). It is about technology, but mostly about prehistoric technology.

I have spent the last four days on a prehistoric metallurgy weekend, run by Fergus Milton and Dr. Simon Timberlake at Butser Ancient Farm in Hampshire. The aim of the course was to introduce us to the basics of prehistoric metallurgy and then teach us the practical skills so that we could take the process all the way from breaking the ore to casting an axe. I decided to take part in the course, not because I am focusing on the techniques of Bronze Age metallurgy, but because the site that I am looking at on Bodmin Moor was very likely to have been created to work the nearby tin sources and I wanted to know how they would have done it and what it would have felt like. I have read quite a bit around the subject, and have a good idea of the steps involved, but it wasn’t enough. As with all of my work, I am interested in the human experience of a landscape or an activity and find it is necessary to get my hands dirty to see and feel what smelting is like – something you can’t get from just reading about it.

The course was quite archaeology focused, and being at Butser Ancient Farm meant there was also a large element of experimentation – rather than just demonstration. We were encouraged to try out different ideas and set up experiments based on our own research aims. The best part for me was that we made every part of the furnace and refractories (tuyeres, crucibles, collecting pots, etc.) ourselves – we even hand-stitched our own bellows.

Hand-stitched leather bellows

Drying out the refractories

After making our refractories we set to digging the furnaces, my group decided to dig a bank furnace and a bowl furnace. As can be seen from this 3D model the bank furnace is unsurprisingly dug down into a bank of earth with a horizontal passage dug into the shaft to hold the tuyere and bellows.

In contrast, the bowl furnace is a simple bowl dug out of the ground lined with a thin layer of clay, with a slightly sloping passage to hold the bellows and tuyere.

In order to fire the furnaces up, all that is needed is a small fire in the bottom of the furnace which is slowly covered with charcoal until the furnace is entirely full. Obviously the bellows need to be continually pumped to get some oxygen into the fire under the charcoal.

Bowl furnace in action

The ore is prepared for smelting using a beneficiation mortar (in our case we used a granite mortar which was probably originally used for grinding flour). Essentially it is as easy as smashing a few rocks and then grinding them down to powder using a stone hammer. This, perhaps weirdly, is the part of the process I was most interested in. I believe that the Bronze Age inhabitants of Leskernick Hill were collected and crushing cassiterite (tin-stone) on-site and I wanted to see how hard it was to do and how long it would take. Simon had some streamed Cornish cassiterite with him and so I got to have a go at crushing it to fine powder. It was remarkably easy and took very little time and effort to go from the rock itself to the powder ready for smelting. The mortar we were using had smooth sides and so the tinstone kept skating up the sides and escaping onto the floor, but perhaps this might have been prevented if we were using a mortar with straighter sides.

As can be seen from the 3D model above, once the ore was crushed we loaded it into a hand-made crucible, ready for smelting. This crucible was filled with a mixture of cassiterite dust and malachite (copper-bearing ore) dust in an attempt to co-smelt them creating a ‘one-step bronze’. The mortar is stained green in this case from crushing up the malachite. Unfortunately on this experiment the hand-made crucible cracked in the furnace and so the one-step bronze leaked out and we eventually found it at the bottom of the furnace. We had also put a layer of crushed malachite directly into the furnace, which smelted away nicely and mingled with the leaked bronze to create a big lump of slightly tinned copper.

A lovely lump of smelted copper (with a tiny bit of tin)

Working my way through the entire process of metallurgy (minus the mining/collecting of the ore or the making of the charcoal) made me appreciate actually how surprisingly easy the whole thing is – and equally what rather unremarkable archaeological remains it produces. This is especially true of our bowl furnace, which when burnt out looked almost exactly like a hearth, complete with burnt ceramic material that one could easily mistake for simple prehistoric pottery. It makes me wonder how many smelting sites may have been misidentified as hearths. After this weekend I would happy to build a small furnace in my back garden and smelt some copper, and I wonder if the smelting furnaces of the Bronze Age were similar, small bowl furnaces in or around the family home.

We undertook a total of 5 smelts and a couple of castings over the weekend, with varying levels of success. Even with the professionals there (Simon and Fergus) things did not always go to plan (crucibles broke, furnaces didn’t heat up enough, molten metal was spilled on the ground) but this, for me, was the key to the whole experience. While the entire process was much easier than I had first imagined, there was still effort involved in smelting a relatively small amount of metal. These mistakes and accidents would have happened in antiquity as well and so even when a whole smelt of tin vapourised to nothing due to the furnace being too hot, I didn’t really regret the 2 hours spent bellowing and in fact felt a little closer to the frustration that might have been felt by the inhabitants of Bronze Age Leskernick Hill. Although I know the chemistry behind the smelting process (just about!) I was dumbstruck by the magical process of turning rock to metal. We literally sprinkling crushed malachite into the furnace and covered it with charcoal, heated it and then found a lump of copper at the bottom of the furnace. It was quite a powerful experience, and one I am sure would not have been lost on the early prehistoric smelters.

This whole weekend has made me realise that just as it is important to walk the hills of Bodmin Moor in order to really get a feeling for what it is like to inhabit the place, it is equally important to build a furnace, crush ore and smelt it to metal in order to find out what it is like to inhabit the activities as well. Of course experimental archaeologists have been doing this for years, but just one weekend of it has already changed the way I am thinking about some of my evidence and will almost certainly have a big influence on at least one chapter of my PhD.

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