November 2015

The next chapter of this book covers the vast swathes of prehistory in the Middle East, taking us from the first migrations of pre-homo sapiens humans out of Africa all the way through to about 6000 years ago just before the first cities of Mesopotamia. Which is rather a lot of ground to cover! So much so that I have split the chapter into two blog posts, the first of which covers the Paleolithic cultures and the second will cover the Neolithic.

The Fertile Crescent

This is not just the story of the Middle East over this period, but also the story of humanity as we go from early humans to modern humans, and from nomadic hunter-gatherer to farmers living in permanent settlements. The introductory 2 page spread for this chapter suggests that one reason everything seems to happen first in the Middle East is due to geography. It's on a crossroads between Africa, Europe and Asia, so it was the best informed region - all knowledge flowed through there as it spread. And then could be combined with the other new ideas from other areas to produce leaps in technology.

Paleolithic Era

Early humans (Homo erectus) begin to spread outside Africa within a few hundred thousand years of their evolution. The earliest traces of humans date to 2.6 million years ago (in Ethiopia) and the earliest non-African evidence is from Dmanisi in Southern Georgia dating to 1.8 million years ago. These hominids presumably migrated via the Levantine corridor, as the only land route between the two areas. The next oldest site where human tools (and three teeth) have been found is in the Jordan Valley. Judging by the tools found at a wide variety of sites across the Middle East there were three or four different waves of migration out of Africa by Homo erectus. One of these migration waves also provides evidence of the first controlled use of fire - which I think I should've known pre-dated modern humans, but if I did know I had forgotten.

The Middle Paleolithic era lasted from around 250,000 to 45,000 years ago, and it was during this period that Homo erectus was replaced by Homo sapiens sapiens and Homo sapiens neanderthalensis. The dominant theory 40 years ago (based on archaeological evidence from Europe) was that first came the Neanderthals and they were then replaced by our own species before 40,000 years ago. Excavations in the Levant have changed this picture significantly. There are Homo sapiens sapiens remains as old as 100,000 years ago at site in the Levant, and Homo sapiens neanderthalensisas young as 50,000 years ago. There have also been skeletons found that display different combinations of characteristics from the two groups. What's more the tools produced in the various different sorts of sites show no significant difference between the sites in terms of material culture and way of life. So perhaps the two species co-existed (for around 50,000 years or so). The double page spread about this era ends with a set of questions we don't know the answers to yet - including whether or not the Neanderthals were actually a separate species.

The boundary between the Middle Paleolithic and the Upper Paleolithic (c.45,000-50,000 years ago) is marked by changes in tool technology. The shift was from tools formed as flakes or points to elongated blades which have a better edge-to-mass ratio and can be more efficiently produced. Interestingly as well as a local development of this tool culture (or perhaps brought by newcomers from Africa) there is also evidence of migration* into the area from Europe. The tools these immigrants brought with them are also blade based, but not the same as the ones produced in the Levant. These migrants are relatively restricted to one geographical region and one time period (32,000 to 30,000 years ago). An oddity of the Levantine Upper Paleolithic culture is that there is no evidence of art: no cave paintings, no figurines, no engravings. If I remember right the same is also true of Chinese prehistory ... is art another of those ideas that is thought of only rarely and then spreads to become universal? Although having said that, we are very limited in what we can find evidence of - music, singing, dancing, drama and so on aren't necessarily going to leave traces in the archaeological record.

*I'm not quite sure from the book why they know (if they know) that it's the tool users that migrated rather than just the technology moving.

The next period of Middle Eastern prehistory is referred to as the Natufian period, and once again it's characterised by a particular sort of tool. They give a technical description in the book, but basically the main form is small crescent-moon shaped tools for hunting and food preparation. The Natufian period falls into two phases: early from ~15,000-13,000 years ago and late from 13,000-11,500 years ago. This culture shows the first signs of sedentarism - with permanent, year-round villages. The communities still seem to have been hunter-gatherers, which was interesting as I previously thought the general idea was that settlement and agriculture happened the other way round. During the second phases of this period there's actually more mobility in the communities, but they seem to have more clearly defined territories even if they're not sedentary. I'm not actually sure what the evidence for this is, they don't mention it in the book. However the authors do say that the second phase lines up with a signicantly drier period and so perhaps there wasn't sufficient food at any given site to support a permanent population. Agriculture may or may not have begun during this period (experts are divided) but taming and domestication of the dog were definitely begun by the Natufians.

In contrast to the earlier Levantine cultures the Natufians are art producers. They produced both standalone things (like decorated bowls and slabs as well as figurines) and personal accessories (like necklaces, belts, etc). And the beginnings of trade are visible - for instance artifacts made of Anatolian obsidian have been found in the core Natufian region (the Levant from the Mediterranean coast to the Jordan Valley). Natufian sites also have evidence of the first large scale cemetaries. There isn't really a pattern to how bodies were treated. Generally the body was buried in a flexed position, sometimes in a single occupant grave, sometimes in a larger grave. Some bodies have decoration and/or ornaments, some graves have carefully place stones, others are just a pit refilled after burial. The book doesn't speculate at all about potential elite/non-elite distinctions - perhaps it's clearly random when you look at the data?

Temple at el Tod

The last site we visited in Egypt last November was a temple dedicated to Montu, which is in the modern village of el Tod. I don't think it gets many tourists - our bus had a bit of trouble getting through the winding streets of the village and we had to walk the last little bit. My main memory of the place is that it was very peaceful, despite being in the middle of the village. There were palm trees throughout the site and it was a little oasis of calm. Even the guardians here were pretty laid back!

My photos from this site are on flickr: click here for the full set, or on any photo in this post for the larger version on flickr.

Temple at el Tod

When you go into the site the first thing you come to is a block storage area with loose bits of the temple that have been tidied up (effectively). Medhat paused here to explain a bit about the history of this temple, using some of the blocks to illustrate his points. The temple was originally built in the Middle Kingdom and early New Kingdom - with later usurping of cartouches by Ramesses II. These parts of the temple are finely decorated and made of limestone. Later during the Ptolemaic era the temple was added to, and the additions are more crudely decorated on lower quality sandstone. Looking round the temple we also found a place where new decoration had been carved over the old. When painted it must've looked OK, but now that the paint has gone it looked a bit odd with columns of hieroglyphs running straight over a scene. As well as the temple proper the site also had the remains of a quay - the Nile or a canal must've once run past the end of this site but now it's landlocked. And a small barque shrine, with quite a lot of decoration. Of course I was also looking for graffiti, and as everywhere in Egypt there was some to be found.

Temple at el Tod

It was quite a small and ruined site, and so I don't have much to say about it. But it deserved its own post as the small peaceful finale to this series of posts as well as the holiday :) It had been a very good holiday.

Temple at el Tod

Prester John was the greatest Christian King who never lived. All through the Middle Ages there were persistent legends (sometimes backed up by apparent documentation) about this powerful priest-king in the East who was ready to bring his powerful armies to attack the Muslims in concert with the Western Crusaders. The experts who discussed these legends on In Our Time were Marianne O'Doherty (University of Southampton), Martin Palmer (Director of the International Consultancy on Religion, Education, and Culture) and Amanda Power (University of Sheffield).

They opened the programme with a bit of a discussion about the historical truths in which these legends might've been rooted. During the early Middle Ages there was a large Christian population in the Middle East and in India. There's evidence that Western Christians were in contact with them - for instance King Alfred (of England) sent some people to India. It's written about as if the journey wasn't anything particularly special - a long way, and a relatively rare event but perfectly doable. These Christians weren't from the same branch of Christianity as the Western Church, and the two Churches would've regarded each other as heretics. They are sometimes referred to as Nestorian Christians, but that is a bit of a derogatory term and it's politer to refer to them as the Church of the East or the Syrian Church. The schism between this Church and Western Christianity hinges round a theological point about the nature(s) of Christ. Western Christianity (or monophysitism) holds that Jesus's human nature was absorbed into his divinity and he had only one nature. However those who followed Nestorious believed that Jesus had two natures that were only loosely connected (this is called dyophysitism) - he was both divine and human and those were separate from each other. So there was a substantial Christian population in the East (probably larger than in the West), which dwindled after the rise of Islam - after which the legends of Prester John began to develop.

The first forms of the legend are known from the 12th Century AD. One of these is an account of a visit to the Pope in 1122 by an emissary from Prester John. It's not clear to modern scholars what, if anything, this is actually based on - if there was any visit from anyone that got garbled in the reporting or if someone just made it all up. The emissary purportedly says that he has come form Prester John's kingdom to the east, and that Prester John had been leading a force to aid the Christians at Jerusalem. However the army had been unable to cross a river on the way, and had been forced to turn back. The account of this emissary's visit gives details of the fabulous force that Prester John had available, and gave hope they would make another attempt to join the Crusaders.

Another early piece of "evidence" for Prester John was a letter that was purportedly sent from Prester John to the Byzantine Emperor in 1165, and subsequently translated into German and forwarded on to the Holy Roman Emperor. This letter goes into detail about what life is supposedly like in the land that Prester John rules. It's an earthly paradise, full of wondrous beasts. Everyone lives long and virtuous lives, and after death they don't rot and will return to life at the Day of Judgement. The kings are always called Prester John and combine the roles of secular and religious leaders in one person. The experts on the programme said that it's extremely likely that this letter was originally written in German - it doesn't read like translated Greek. There's also no obvious reason why the Byzantine Emperor would be forwarding his post on to the Germans! The most plausible explanation for the letter is that it's a piece of propaganda produced by the Holy Roman Emperor's court. At the time he and the Pope were embroiled in a power struggle, and a document that explained how perfect everything would be if the secular leader of a country was also the spiritual leader was rather useful for the Holy Roman Emperor.

It seems odd to us as modern people to think that these tales of an earthly paradise (of an incredible nature) were so easily believable, but the programme pointed out that during this era there was a large body of literature of tales of wondrous lands beyond the known world. This is the period where maps have areas labelled as where the Doghead people live, and where the people live who have their faces in their torsos. Around the 12th Century and onwards this begins to change, as more people travel and write more accurate travelogues. It's a slow change though - not all the early travelogues are written by people who've actually been where they claimed to be. For instance the author John Mandeville apparently travelled to Prester John's land and met him - but a lot of other things in Mandeville's book are made up, and most of the rest appears to've been copied from other books. There's no indication Mandeville actually went anywhere! He's not the only example of this from the time, either.

The rise of the Mongols changes the legends of Prester John a bit. There are some stories about Prester John being conquered, but other stories suggest that maybe he was never in Central Asia and his land is actually in India. Another blow to the believability of the legends is that travellers visit the Mongols from Europe, and whilst they meet Christians they don't meet or find any evidence of Prester John. (Nor do they find any wondrous beasts, or Dogheads etc.) They do try and make an alliance with the Mongols against the Muslims, but this doesn't interest the Mongols.

And later still as China becomes more well known to Europeans it becomes ever more implausible that Prester John and his kingdom could be anywhere in Asia. By the 14th Century AD the legend of Prester John has shifted to Africa, and Ethiopia is the new focal point. As an aside one of the experts (I forget which one) said that you could think of the 14th Century as "the century when Ethiopia discovered the West". Ethiopia had been Christian since the early AD period, and in the 14th Century they sent emissaries to the Pope and to some of the European kings. They seemed to fit in with some of the Prester John stories - in particular the "long lost Christian Kingdom" aspects of it. And they also seemed to fit other legends about the Queen of Sheba. But the legends still weren't true. Which apparently didn't stop European travellers from visiting Ethiopia and asking the rather bemused locals about Prester John.

They finished up the programme by talking about whether or not people actually believed the stories at the time. I think the overall conclusion was that mostly they probably didn't, it was just a good story or a useful one for propaganda purposes. However there were examples of people who did believe - for instance during the Crusades some commanders made strategic errors because they believed they were about to be joined by Prester John's army any time now.

On Sunday Kathryn Piquette came to the Essex Egyptology Group to talk to us about the work she's been doing using Reflectance Transformation Imaging (RTI) to examine the Narmer Palette (and some other ancient Egyptian objects). She started her talk by giving us context for the Narmer Palette, and then explained the imaging technique she is using. She then showed us several examples of objects she's studied before returning to the Narmer Palette to tell us about her findings so far.

The Narmer Palette was discovered in 1898 by Quibell & Green at Hierakonopolis, near the "Main Deposit". This was a cache of sacred objects that had been buried around the time of the 5th Dynasty when they were no longer being used. The palette dates to around 3100BC, and is a larger version of the type of palette that was used by the ancient Egyptians to grind eye makeup powders. The normal ones are quite small, and plain, but this ceremonial one is bigger (around 65cm by 40cm) and richly decorated. It's made from mudstone, and Piquette said it's surprisingly heavy so she thinks of it as a semi-portable object. The art on it depicts the first Pharaoh of a unified Egypt, Narmer, in a selection of scenes that depict his power & his kingship. This includes a smiting scene of the same type as those you see on temple pylons in Egypt right up to the end of the Ptolemaic era. Most previous research on the palette hasn't been interested in the object as an actual physical artifact. In part this is because it's hard (for bureaucratic reasons) to get access to it to actually study it in the flesh (so's to speak), even tho it's on display in the Cairo Museum it's behind somewhat grubby glass and it can be difficult to closely inspect it. And so people study old photographs of it or line drawings of the art that have been made. This only serves to enhance the general tendency in Egyptology to study the art and the texts in isolation from the physical objects they're on. So the previous studies have concentrated on things like what the art tells us about the history of the period, how the iconography has changed or not changed over the millennia after it was made, and so on. Piquette is more interested in how the physical object was made - what it tells us about craftsmanship at the time. As well as having a much closer look at the details of the artwork.

She is using a technique called Reflectance Transformation Imaging to do this examination. This involves building up a composite image from several different photographs, each taken with the light source in a different place. This lets you use imaging software on a computer to play around with different lighting angles, and to use a variety of enhancement algorithms in conjunction with this. Piquette said it's like if you're looking at an old coin and trying to see the writing/picture on it - you tip it back & forth trying to get it to the point where the shadows make the inscription clearer. I also thought it's like how guidebooks for Egyptian sites often say things like "visit in the early morning as the angle of the light makes the inscriptions clearer". Obviously the beauty of RTI is that once you've done the hard work of taking all the carefully lined up photos you can then revisit the image over & over looking at what you can see with different light angles and different enhancements.

Piquette next showed us several examples of objects she's used RTI to examine. This was really interesting to see, as she showed us the actual images and was moving the light source around to show what showed up under different conditions. It's a little harder to write about without the pictures tho - I'll just try & give a flavour of the sorts of things she pointed out to us. One of the objects was a 1st Dynasty stela where she showed us the tool marks that showed how it was made. On a Roman Mummy Portrait she showed how the technique could be used to distinguish the original pigment from some much later repair work - which is important information for the conservators working on the object. Another object was a Greek magical text written on a sheet of lead and placed in a water cistern around 400BC - as you can imagine it was pretty corroded. At first when she showed us the image of it, it looked like there was nothing readable at all. But by turning on one of the enchancement algorithms and altering the light angle suddenly the text popped out and was visible.

While we had our coffee & cake break I'd been wondering if the technique was capable of being used on large outdoor structures - I'd been thinking about Vulture Rock earlier in the week for the blog post I published on Wednesday and it'd be awesome to see these sorts of images for that. And the first object she showed us after the break wasn't from Vulture Rock but was a similar sort of thing - a large rock in a wadi near Aswan which has rock art on it. She talked a bit about the difficulties of using RTI outdoors at this point (and it came up again in the questions at the end). Stability is one of the key requirements for RTI as all the photos must be identical except for the light source - so if the only place to set up the tripod is on sand, or if the wind picks up and blows the sand around, then that can cause problems. Amount of ambient light can also be an issue, and the normal technique is to use a flash gun that's significantly brighter than the ambient light. Which isn't that easy to achieve if you're outside under the Egyptian sun.

The last example she showed us before returning to the Narmer Palette was an inscription on a gneiss bowl. She used this to illustrate again how the tendency to divorce the art/text from the physical object can remove information. The original publication of this inscription doesn't actually look much like what's on the bowl - the hieroglyphs are tidied up into standard forms, and the orientation of the text is reversed to better fit with Western conventions. So that tells you what it says but you've lost all the information about what the inscription is like. When she examined it using RTI she could see that in contrast to the beautifully made bowl the inscription is actually pretty crudely done. Each line of the hieroglyphs has taken several strokes of the carver's tools to make - and they all seem to've slipped across the surface past the line where they should've been. In one place the chisel looks like it skidded a long way round the rim. Piquette also said that she thinks it should be possible to figure out if the carver was right or left handed by the directions the tools seem to've slipped the most.

Piquette now returned to talking about the Narmer Palette. It had taken her several years to negotiate permission to photograph it, and then a couple of days before she was due to start work it suddenly seemed as if the permission had been granted without understanding what she needed to do! In the end she was able to persuade them that it would be safe and a good idea for her to take these photos with the palette out of the display case, and she was able to take some photographs. She only had 2 hours to work on it, in a slightly too cramped space, so she wasn't able to do as many detailed images as she'd hoped. What she succeeded in capturing were two overview images, one each of the front and back, and two detailed (i.e. zoomed in) images of the top left and top right quadrants of the Smiting Scene side of the palette. She hopes to have a chance to go back and take more detailed images of the rest of the palette and also examine the thick edges of it. But that requires renegotiating access with the new director at the museum.

One of the things she can see using RTI are the tool marks where chisels have slipped, or where the design was blocked out before the detailed carving started. There are places where the design seems to've been changed - so it wasn't entirely agreed upon before the carver(s) started work. Repeating elements within the design are also not standardised. For instance there are four large cow heads at the top of the palette (two on each side) and they aren't identical. One of them has a mouth that looks just like the eyes (so it looks like an open mouth). The other one on that side has a line across the mouth (like the lips are closed), but there are traces if you look closely that indicate the mouth may once've been open. The two on the other side both have closed mouths. Did the carver start with the open mouthed one and then decide it looked better the other way but never went back to alter the first one? Or did someone else do that one who had a different style?

RTI also lets Piquette see details in the carving that haven't been noticed before. For instance the figure of the Pharaoh wearing the Red Crown seems to have a chin strap holding the crown on. Which maybe shows something new about how the crown was actually worn (perhaps throughout history, perhaps only at this time). There is also potential information to be had about how the Egyptians displayed dead enemies at this time. On one side of the palette are nine corpses of slain enemies with their heads removed & placed between their legs. Closer inspection shows that all but one of them have also said their penises removed and placed on top of their heads. That had been speculated about before from inspection of a cast of the palette but Piquette has been able to show that it looks like that's the case on the real thing too. There are also indications that some of the enemies are laid out on their bellies and some on their backs. The one who has been less mutilated than the others is on his back and Piquette wonders if the different positions have to do with different statuses of the enemies. Was the man in charge laid out in a more respectful way than his troops?

This was a fascinating talk, much more so than I think my writeup makes it seem because we actually got to see the images. As Piquette's results are still preliminary data there were more questions than answers in what she was telling us about the Narmer Palette. And that's quite exciting for an object that's been known of for over a 100 years - the idea that there's still a lot more we could learn from it even after all that time.

Vulture Rock

El Kab is a couple of hours drive south of Luxor and was the furthest south we went on this trip. There are several different Ancient Egyptian sites at or near el Kab, and we visited four of them, covering a sweep of history from predynastic (and perhaps before) through to the Ptolemaic era. The site is pretty big - we were driven through it to visit the various bits and it didn't feel silly getting back on the coach rather than walking. This is also the area of Egypt where the predynastic sites of Nekheb and Nekhen are; Renee Friedman gave a talk to the EEG about Nekhen last November just before we went on holiday. I think we saw the enclosure wall for Nekheb, but nothing inside.

My photos for this site are, as usual, on flickr - click here for the full set or on any photo to go to its flickr page.

Amenhotep III era Temple

Amenhotep III Era Temple at el Kab

At the far end of the site was a small 18th Dynasty temple dedicated to the goddess Nekhbet. Nekhbet isn't just the local goddess of the area (which she was from predynastic times) but also evolved into the patron goddess of Upper Egypt. It was a rather unprepossessing temple from the outside, at first glance rather small and plain. Inside, however, seemed rather bigger and a lot of colour remained on the decoration. There was also a lot of graffiti on the walls (leaving one's mark was a bit of a theme for this day). The bulk of the graffiti was clumsily carved by Victorian era tourists, but there was also some older stuff in hieratic and hieroglyphs.

Amenhotep III Era Temple at el Kab

Once we'd spent some time looking at the inside we went back out and had a proper look at the outside. It wasn't as dull as first glance had suggested - whilst there wasn't much official decoration on the walls the priests etc had left their mark in other ways. On the floor around the temple were game boards carved into the flagstones. There were also carvings of outlines of feet, I think the purpose of these is so that the carver is eternally standing next to the temple.

Vulture Rock

Vulture Rock

Vulture Rock was my favourite part of this site. It's a rocky outcrop that looks a bit like a (headless) Egyptian vulture hieroglyph and it is covered in carvings. There's another large rocky outcrop nearby that is also covered on every reachable surface by carvings. These range from predynastic or prehistoric carvings through to the Old Kingdom era. The older stuff includes a large picture of a boat with enclosures & animals on it, as well as numerous animals and human figures (some of whom have their arms curled over their heads like you see on predynastic pottery).

Vulture Rock

The more recent (5th & 6th Dynasty) carvings were more elaborate and more wordy. There were even raised relief inscriptions, and offering stelae complete with the vignette of people making offerings to a god. This wasn't just graffiti, not the equivalent of "Kilroy was here" that we saw in many of the temples and tombs we'd visited on the trip. The later inscriptions here looked like they were done by someone who had a decent idea of what they were doing and some sort of official sanction.

Vulture Rock

For a site I found so fascinating I don't have much to say about it. I think what appealed the most was the sense of continuity. This had clearly been a significant site for centuries, if not millennia. And even though there was a clear difference between the animals etc carved by the earliest people and the detailed inscriptions of the later people they were still linked by a common desire to leave a permanent memorial of their visit to the site. And even tho it wasn't graffiti like the Victorian stuff in the temple we'd just visited, there is still that sense of continuity coming up so close to our own time (and if there weren't so many guardians etc around I'm sure we'd find more modern graffiti in these sites too). It seems to be a part of being human, the urge to make some mark that'll outlast you and show that you existed too.

Ptolemaic era Temple

Ptolemaic Temple at el Kab

The next part of the site we visited was a small temple dating to Ptolemaic times which was carved into the hillside. There was also a nearby shrine or chapel which was a bit older, from Ramesses II's time. Outside the temple there was a small enclosure wall, which had several examples of graffiti on it continuing my theme of the day. These were fairly crude, which stood out particularly after seeing the well done carvings on Vulture Rock which were so much older.

Ramesses II Era Shrine at el Kab

The nearby chapel had the remains of a triad statue in the centre of the room. Despite no heads on the figures, and only a very eroded inscription, we worked out that the central figure was likely to be the vulture goddess Nekhbet.

18th Dynasty Tombs of Nobles

Stairs up to 18th Dynasty Tombs at el Kab

We finished at el Kab by looking at four tombs of 18th Dynasty Nobles. The key one here is the tomb of Ahmose, son of Ibana. He had been involved in the wars to reunify Egypt at the end of the 17th Dynasty. Clearly he was proud of this, and on one of the walls of his tomb is a lengthy hieroglyphic biographical text which includes many details of the conflict. In fact this is where a lot of our knowledge of this conflict comes from. The other three tombs were those of Paheri, Setau and Renni. And I'm afraid they've all blurred together in my head somewhat. I remember that the decoration wasn't in terribly good nick, but you could see from what remained that it had once been fine work. And of course there was Victorian graffiti in the tombs. In fact in retrospect I'm mildly surprised that there wasn't any Victorian names at Vulture Rock - perhaps they just never visited the site.

Ankhtifi's Tomb at Mo'alla

Eileen Contemplating the Tomb of Ankhtifi

Mo'alla is not part of el Kab, in fact it's more than halfway back to Luxor - but I'm appending Ankhtifi's tomb onto this post as I have no photos from there (it being a tomb) and not that much to say. This is a tomb that stands out from most of the others we visited - it is from the First Intermediate Period, so older than most of the ones that we visited during the trip. Ankhtifi was Governor of the local area, and due to the breakdown of central government at the time he was pretty much a minor King. It felt like a different layout, a single larger room with many pillars in it. And the art style was noticeably different to the New Kingdom tombs we'd just looked at. I particularly liked the detail in the hunting & fishing scenes. It was also particularly interesting to me as we'd heard a talk by Glenn Godenhoe at the EEG a couple of years ago where he talked about his work on this tomb. There are inscriptions on the tomb walls which paint a picture of the lawless time that Egypt was going through - but as Godenhoe pointed out this was more about showing how awesome Ankhtifi was than about what Egypt was actually like at the time.

Glass is odd stuff. We've been making it so long that one tends to forget that it's both artificial and really quite odd. The In Our Time episode about glass talked both the science of glass and glass-making, and the history of it. The experts discussing it were Dame Athene Donald (University of Cambridge, current Master of Churchill College, my old college, but here in her context as a physicist), Jim Bennett (University of Oxford) and Paul McMillan (University College London).

On the programme they intertwined the historical and the scientific discussion, but I thought the joins showed rather more than they usually do and so I'm going to split the threads up in my writeup. We first know of glass manufacturing about 5,000 years ago, by the ancient Egyptians who made beads of it initially. Over time they learnt to make larger and more complex objects like bottles & ornaments. The Romans developed the technology further. They invented most of the techniques that were used before the Industrial Revolution, like glass blowing for example. In ancient Egypt glass was primarily used for decorative or luxury goods, but the Romans used glass for both everyday and finer objects - including wine bottles (which struck me as an awfully modern way to store wine!).

In the Renaissance era the Venetians were famed for making particularly fine quality glass. The city attempted to keep a monopoly on glass-making by keeping their methods secret & forbidding glass-makers to leave the city. Which didn't entirely work, unsurprisingly. One of their secrets was a way of making very transparent glass which was useful for lenses. Something I learnt from this programme was that spectacles first appear in the 13th Century AD which is much earlier than I'd assumed. Once lenses were being made to correct people's sight it was only a relatively short step to making lenses for scientific instruments. Glass is part of the Enlightenment's scientific revolution - not just lenses but also for making scientific instruments or vessels. There is a feedback loop between the demands of the scientific experiments driving new glass making technology and better glass instruments expanding the possible experiments that can be done. Industrial production of glass as we know it today begins in the Industrial Revolution.

The whole of the history discussion was very Eurocentric so I had a little look on wikipedia after we'd listened to the programme to see whether this was a fair reflection of the world history of glassmaking. The answer (based on a tiny amount of effort on my part) is ... maybe? Glass making in China appears to've arrived late - during the Han Dynasty and probably influenced by trade goods from the Roman Empire. I didn't find anything about the Americas, so I don't know if that means they didn't invent glass making or if no-one cared enough to add it to wikipedia. It's odd to think that something so ubiquitous today might've been discovered once & once only.

Making glass (not good glass, just glass) is deceptively simple. In essence the process is to heat up sand till it melts, and then cool it very quickly and you end up with the transparent solid that we call glass. One of the experts pointed out that the necessary temperatures are those that would be reached by a bonfire on a beach - so it was probably discovered in Egypt by people (briskly) putting out campfires in the desert. Although a large body of empirical knowledge of how to make glass was built up over the next 5,000 years it was only relatively recently that we gained any understanding of what is actually going on, and the science of glass & glass-making is still not entirely understood. It's actually more difficult to make glass out of pure sand than when there are impurities present, pure sand needs a quicker cooling step. So when making glass other things are often added - like potash or lime.

One of the complicated things about glass formation is that the phase transition from liquid sand to glass is not well defined - which is an oddity in physics. An example of a well defined phase transition is that from liquid water to ice: it happens at 0°C no matter how you cool the water. But the point at which liquid sand becomes glass depends on the precise starting conditions and the precise heating & cooling regimen - and it isn't predictable using the current state of knowledge. Glass isn't even a usual solid - it's not crystalline, and that's why the speed of cooling is important. If it cools too slowly it will crystalise and you don't get glass. So instead of the atoms lining up in neat little rows they appear to just stop where they are. This non-crystalline nature of glass is what gives it some of its characteristic properties. It is brittle because there are no planes of atoms able to spread over each other when pressure is applied. I think they also said that the transparency is down to there being more routes for light to take through the structure, but I'm not sure that makes sense to me so I may've mis-remembered.

Glass in the technical sense is a broader term than just silicon glass (the stuff we generally call glass). You can make a glass using sugar - that's what sweets like glacier mints are made of. And something I knew but had never really thought about is that spectacles & things like motorbike crash helmet visors aren't made from silicon glass. Instead they are made using large polycarbon molecules - these can never crystallise so are much easier to work with. And the glass produced is not prone to fracturing, which is obviously important in those usages. I assume there are other downsides which mean we don't use these glasses for all applications.

From the title I hadn't expected this to be as interesting as it was - I didn't realise how much wasn't known about glass (nor how unique a discovery it was).

This is an index and summary of the things I've talked about over the last month. Links for multi-post subjects go to the first post (even if it's before this month), you can follow the internal navigation links from there.


Josephus - In Our Time episode about the 1st Century AD Jewish Roman historian Josephus.

Total: 1


"Understanding Egypt: Language, Layers and Meaning in the Nile Valley" Carl Graves - October EEG meeting talk.

Total: 1



Doctor Who: Under the Lake.

Total: 1


Armada: 12 Days to Save England - series about the Spanish Armada presented by Dan Snow.

Total: 1


Egypt Holiday 2014: Deir el Bahri.

Total: 1

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