Natural Astronomy

There’ll be plenty to see in the evening sky after sunset at 9.26pm. To the west Venus will be extremely bright at magnitude -4.0 (the lower the number the brighter something is). When you see it you won’t be able to mistake it for anything else. That will be setting at a quarter to midnight, so there’ll be plenty of time to see it.

Position of the planets at sunset. Click for full size.

Moving to the left, are Mars, Saturn and the Moon. Mars will be magnitude 1.3 so it won’t be the brightest thing in the sky, Arcturus and Vega will be brighter but it’ll still be easy to find. If you’re struggling find the Plough. The two pointer stars that point up to the Pole Star will be more or less also pointing down to Mars this evening. Mars sets at a quarter to one, but if you want to see it realistically you’ll have to be looking before midnight. If you’re lucky it’ll have a slight ruddy glow. Saturn will be the only bright object between Mars and the Moon. In fact it’ll be slightly brighter than Mars in perfect atmospheric conditions, but I doubt my eyes will be good enough to measure that.

The Moon will be in Virgo, near the star Spica, which was thought to be a sheaf of corn in the hand of Ceres, if you’re Roman, or Demeter, if you’re Greek. Fans of mythology will be keenly aware that Demeter/Ceres had a daughter with Zeus which makes her not technically a virgin, but the Greeks called her Parthenos and that usually gets translated as virgin. To find Spica usually you’d follow the arc of the handle of the Plough to Arcturus, and then Spica is the next bright star down. This night it’ll be the closest bright star to the Moon. It could be hard to spot because the Moon will be bright. It’ll be 69% lit, nine days old and waxing gibbous. It’ll be more or less low in the sky to the south at sunset and set around 1am, which is astronomical midnight. It’s not the same as civil midnight because these days Stonehenge is on Daylight Saving Time, like the rest of the UK.

Stars at 1am over Stonehenge. Click for full size.

Around 1.20am Jupiter rises. It’s likely that you’ll need to wait till 2am to get a good view. It’ll be shining in silver at magnitude -2.4 and, because Venus will have set, it’ll be the brightest planet on the sky. Jupiter will have a partner, but it’s highly unlikely you’ll see it at Stonehenge. Uranus will be close to Jupiter. If you hold out your hand at arm’s length then Uranus will be five or six little fingernail widths to the right of Jupiter. Normally there’s no chance at all of seeing Uranus, but at the moment it’s at magnitude 5.8 which puts it right on the limit of human vision. If you have very good eyesight and the atmospheric conditions are perfect you’ll see what looks like a very faint star next to Jupiter, and that’s Uranus. But even if we have that, I still doubt you’ll see it.

The reason is that it takes time for your eyes to adapt to the dark. Ian Musgrave says it takes a few minutes to see down to magnitude 5 or 6. Your eyes need to build up chemicals to make them more sensitive. Every time you see a bright light, like car headlights from the nearby roads, torches from other visitors who – quite reasonably – don’t want to break their necks walking around and any lighting from English Heritage this adaptation will be lost. On top of this there’s light pollution. We don’t just use energy lighting streets. A lot of energy is used to light up the sky, for no obvious reason. This reflects from any water droplets in the atmosphere and gives a sodium glow to the sky. Even cities over the horizon will be visible by their light pollution and this will prevent you from seeing some of the stars. You’ll stand a better chance of seeing Uranus if you use binoculars.

There is another difficult-to-spot object in the sky. To the north near Capella is Comet McNaught. Searching on the web for this is no help. There’s a lot of Comet McNaughts because Robert McNaught has found over fifty of them. This one is Comet McNaught 2009 R1. The current figures I have are that it will be between magnitudes 5 and 6. If that’s the case then you might not see much without dark-adapted eyes and it’s a binocular object. This figure is uncertain though because the comet is getting closer to the Sun. Around June 30-ish it’s predicted to be as bright as magnitude 2. Capella is not too hard to find. It’s the only bright star above the northern horizon, and it will be due north around half-past midnight. The comet will be a couple of degrees above it. Look for a fuzzy star.

The Sun is due to return a few seconds before 4.52am. Again, daylight saving explains why the Sun sets less than three hours before midnight, but doesn’t rise till almost five hours after.

IFOs

Or, if you don’t tell your friends what they are, UFOs.

The big events will be the passes of the International Space Station. There’ll be two and half over Stonehenge. The first will be at 1.08am till 1.10am. You’ll be able to see the ISS dropping from 38º up in the sky to the southeast down to the horizon. It’ll be bright (magnitude -2.7) but it will also be fast. This is the half appearance and you may not see it. You best chance is to be looking at Aquila, the brightest star in the southeast at this time, and it should appear near there.

The next appearance is the best. At 2.40am it will rise in the west and pass overhead before setting in the east at 2.46am. It will look like Venus did, but it will visibly be moving across the sky. It could look like an aeroplane and if anyone else says that you might want to agree before pointing out that there’s no visible flashing lights like there would be on an aeroplane. It will also be travelling too fast. Get your friends to rule out other obvious causes like Chinese lanterns, reflections of headlights, planets and so on so that you sound like you’ve been reluctantly convinced that whatever you saw was not of this world.

Then at 4.15am you can make everyone jump out of their skin by yelling “They’re BACK!” when the ISS makes another pass from the west again. This time it will set 4.23am in the eastsoutheast.

For extra UFO points you can also try pointing out an Iridium flare. This is a sudden bright reflection from one of the Iridium communications satellites. There are two during the course of the night. At 10.52:44pm on June 20 there’s a magnitude -1 flare westnorthwest above a handspan above the horizon. At 3.22:06am there’s a brighter magnitude -4 flare in the eastsoutheast. These will be fast; they’ll last for just a few seconds.

Flare Simulation. Source: Wikimedia Commons

Heavens Above, where I got these details from for the ISS and Iridium also has some transit times for fainter satellites, but the night sky is littered with satellites. If you see anything that looks star-like moving across the sky over six-eight minutes then it’s quite possibly a satellite. Some of these could be mistaken for aeroplanes. Registering on the site will enable you to print off your own star charts for ISS and satellite passes. If you’re on twitter @twisst can tell you when the ISS is passing over your location and send you alerts.

If you’re interested in visiting Stonehenge for the solstice this year and want more practical advice, like remembering to pack toilet roll, you’ll find Heritage Key helpful. And if there are clouds, it might not all be bad news.

Around 1900 Greek divers found a shipwreck off the coast of the small island Antikythera. They found various statues and bronzes and some small lumps of corroded gunk that no one paid much attention to. Everyone ignored the gunk until parts of it broke. I’ll diplomatically not speculate on how it broke. What people found were that the lumps of corrosion were part of a mechanism that included lots of circles that looked like clockwork gears. This was a huge surprise, because no one suspected to find these kind of gears in the ancient world. Careful study suggested the machine was some sort of device for tracking the position of the Sun and Moon, and also a mechanical calendar. Various reconstructions were attempted and this video from New Scientist shows what people thought about the mechanism till a couple of years ago.

There has been a recent spate of articles on the mechanism. This is due in part to Antikythera Mechanism Research Project studying the remains through X-ray tomography. This has produced the most detailed view of the mechanism through all the corrosion. It’s also due to the same group being generous in providing other researchers with material. So while James Evans, Christián C. Carman and Alan S. Thorndike might not be members of the research group, they have had the material to write a new article on Solar Anomaly and Planetary Displays in the Antikythera Mechanism. Displaying the Solar Anomaly and the positions of the planets are two astronomical different problems, but how you solve one puzzle will affect how you solve the other.

The Solar Anomaly

The Greeks thought astronomical bodies moved through the heavens in circles. It’s an idea that hung around until the seventeenth century, because in any sensibly organised universe heavenly bodies would move in circular orbits. It wasn’t until 1605 when Johannes Kepler worked out that the universe wasn’t perfect and that planets move in elliptical orbits. Apart from not being circular, there are other problems with elliptical orbits. Planets do not travel with a constant speed. They’re faster when they’re closest to the Sun at perihelion and slower when they’re furthest away at aphelion. You should see this in the animation below.

The ellipse is exaggerated for effect, as is the speed. I doubt anyone would want to spend a year watching a real-time animation. In reality the difference between a circular orbit and the Earth’s elliptical orbit means that the Sun can be up to two degrees away from where you’d expect it. For scale, if you hold your hand out at arm’s length and look at your fingernail on your little finger, that’s about half a degree across. So the error is not a lot, but it’s noticeable. This is a problem if you’re creating a scale on your own Antikythera Mechanism to measure the position of the Sun. You can’t use a circle with a uniform scale, centred on the Sun gear, so what can you do? There are two obvious options.

One is that you don’t divide your circle evenly. You distort the scale slightly so that the longer half of the year covers sightly more than half the circular scale. The other way would be to have a circular scale, but make the centre of the scale slightly off-centre from the rotation of the Sun gear, so that the circular scale is divided into two unequal halves. This allows a for a uniform scale, because the Sun marker will have to travel slightly over half a circle to cover the longer half of the year. Evans, Carman and Thorndike looked to see if they could measure the divisions on the scale and see which solution the maker of the Antikythera Mechanism used.

The only reason this project was a remotely sane idea is due to the quality of the images the Antikythera Mechanism Research Project has produced. By sticking it in a X-ray machine like a medical scanner they’ve been able to peer beyond all the corrosion and patina on the gears and get a better look at the scale. They have also been able to creatively light the surface to texture map the exteriors. It gives unprecedented detail of the mechanism, and it’s allow Evans, Carman and Thorndike to say that the scale is not uniform. Each division is measured to match the elliptical orbit to the circular scale. The authors note that zodiac scale is not uniformly divided on some astrolabes. The scale does create some difficulties, it makes makes tracking the planets difficult. Just as the Earth has its own eccentricities when orbiting the Sun, the same is true for the other visible planets.

Tracking the Planets

Before working out how the planet displays fitted into the device, it’s first necessary to show that there were planet displays in the first place. It’s certainly more awesome if there is, but there’s not a lot of evidence for this. The gears needed to drive planetary displays are missing. Missing gears are not inherently a problem. In fact it would be stranger if there were exactly the right number of cogs for everything, because it’s highly likely that not all the parts of the mechanism have been found. What would you do with the extra bits if they were found? At the same time speculating on missing gears is an excellent opportunity to make the device you wish for. If you can just make up wheels and the number of teeth on the cogs you can have anything. The researchers have to walk a tightrope between what will work and what they have as evidence.

Evans et al. are obviously aware of this and make the point that you could make planets that whizz back and forth against the zodiac if you used enough gears. They also make the point that if you were going to do that, then making a non-uniform scale for the zodiac is odd. It’s not that you can’t work around it, it’s simply that you’d be making life unnecessarily difficult. So instead they’ve gone back to the inscriptions to see what they actually say about the planets. There is a reference to Aphrodite (Venus). It describes the ‘stations’ of the planet, the times when it appears to stop in the same place in the sky. Evans et al. argue that this is a bit weird. If you were turning the drive handle and the planet wasn’t moving much you’d see where the station was. There’s also a reference to a conjuction and they point out this would be visible too. They concede it could be something that the user could check with the device, but they suggest it could be something more interesting.

The ancient Greeks were keenly interested in heliacal risings. As the Earth travels round the Sun, the background stars appear to move. The light of the Sun blots out different stars depending on the time of year it is. The first appearance of a star in the morning sky is its heliacal rising, and it happens once a year. So if you known what rises when, you can check the time of year each morning – if there’s no clouds blocking the view.

If that’s the case, then the inscriptions be a method for mentioning this kind of event, that wouldn’t be obvious from just looking at the device? Evans et al. say that the Venus display wasn’t a little planet trundling round the zodiac. Instead they say it was a pointer that rotated once ‘in approximately 584 days’. Around the zodiac scale were Greek letters and when the pointer faced a letter the user could read what that meant, like Venus is in conjunction with the Sun. The word approximately is the key to this. Venus completes eight revolutions of the Sun for every five Earth years. So if you see Venus in the sky at 8pm on day then, if you come back to the same spot eight years later at 8pm, you’ll see Venus in the same place in the sky. That’s not quite accurate, it’s four days too long, but it’s close enough for most people. Whoever designed the Antikythera device wasn’t ‘most people’.

Evans et al. say that better approximations were known. One better approximation known to ancient astronomers is that Venus completes 1151 revolutions around the Sun every 720 years. Viewed from the Earth that means that Venus will complete 720 revolutions against the background stars (a synodic period) every 1151 years. That is better, but gives us problems. How do you cut a gear with 1151 teeth, and where would it fit into the mechanism? Most of the gears tend to have 20-70 teeth, though there is a freak one with 224 that has no obvious astronomical purpose. There’s nothing like a 1151 tooth gear, so that’s quite an invention. What the authors propose is that if you can’t have a simple ratio, you need to get close, and then use another ratio refine it. They go through a few possibilities around the ratio 64/40. This is the 8/5 ratio that most people use to track Venus, scaled up so that there’s a realistic number of teeth in the cogs. That allows them to see if something can be done with a variety of ratios between 62/40 and 66/40. After a lot of division they get a gear train 7/40 x 63/25 x 29/8. The problem is that like the 8/5 ratios, you couldn’t cut reliable gears with so few teeth as 7 and 8, so they had to scale up the numbers. What pops out is 90/20 x 63/25 x 29/224.

This could explain why there’s a 224 tooth wheel in the mechanism (it also explains another 63 tooth gear that no one had a use for), but by itself I’m not convinced. There’s plenty of planets and plenty of multiples for the ratios. It could be cherry-picking to select the one that conveniently has 224 in the answer. Fortunately, they provide evidence that it wasn’t just Venus that was displayed but Mercury and Mars too. They point out that Babylonians recognised that 133 synodic cycles for Mars is 284 years and that neatly factorises into 128/19 x 71/224. That 224 wheel appears again. They find similar simple gear trains based on the 224 wheel for Mercury, Jupiter and Saturn. What makes me more convinced is they recognise this all has to fit into a box 18cm (about 7 inches) wide. A diagram in the paper shows the gears could all fit inside the box comfortably.

What Does the Antikythera Mechanism Tell Us About Ancient Astronomy?

A reconstruction of the Antikythera Mechanism. Photo (cc) Tet_Sy

What I like about this paper is that it’s not just about the numbers. Evans, Carman and Thorndike relate it back to what we know about ancient astronomy. They use evidence of Babylonian observations to explain the mechanism, but that is reasonable. After the conquests of Alexander the Great Babylon became part of a Greek Hellenistic Kingdom, and there’s evidence that the Greeks were aware of Babylonian astronomy before then. They point out there’s been some attempt to relate this to the astronomy of Hipparchus, but they also note some problems with that.

One obvious problem is that we don’t have much of Hipparchus’s work. We have the works of Claudius Ptolemy, and they survived because the Christian church found them useful, but if Ptolemy had the right answers the why keep any others? For this reason what we have is a keyhole view of ancient astronomy. The ratios in the Antikythera mechanism are consistent with some of this, but other bits aren’t. It doesn’t look like there was just one canon of astronomical knowledge. It’s possible there were a number of different methods used for different jobs. If that’s the case then the historical evidence is simply the tradition most useful to Arabic and Christian scholars.

It also means that the reconstruction opposite is sadly too simplistic. It looks like there would have been displays for each of the planets as well as the Sun and Moon. Evans et al. even suggest that there could be an display for the winds. That’s not as bizarre as it might sound. The winds are generally seasonal, so they loosely correlate with the Sun. We also know from other Greek inscriptions that astronomical observations like Arcturus is rising are also intermingled with meteorlogical and ecological signs, like the return of swallows from migration. A solar gear could drive a winds display and there seems to be enough space for one.

How do I know there’s enough space? It would have been nice to finish with a diagram of the completed model, but copyright laws being what they are it’s difficult to be sure if I can reproduce one. As it happens that’s not a problem because there’s something better than that. You can download the paper yourself from James Evans’s website. Scroll down to Selected Articles: History of Science and the pdf of the article is linked in the list of other papers.

Evans, J., Carman, C.C., & Thorndike, A.S. (2010). Solar Anomaly and Planetary Displays in the Antikythera Mechanism Journal for the History of Astronomy, 41 (1), 1-39

Is an ancient history or archaeology of religion a sensible project?

I’ve got an interest in ancient science, but one of the things most people researching ancient science would agree that science in the ancient world didn’t really exist. There’s something that’s a more systematic inquiry about nature, but something like natural philosophy would be a better description for the classical world. I’m not sure that the same term would work for other societies because philosophy carries a lot of baggage too. So when academics talk about ancient science, there’s this undercurrent that we’re not talking about science. Ancient science is not the same as modern science.

I’ve got an interest in ancient religion too. I’m not so interested in the content as such, more religion in a socio-political context. That’s something you can say that makes sense to modern people. If you said the same thing in the ancient world they’d think you were mad. It’d be a bit like saying you’re interested in fish, but only the ones that live in water. In the ancient world it was accepted that religion was entwined with civic life. There’s a second problem that what we call religion has developed from its ancient roots.

One (of the many) impressive posts on Phil Harland’s blog is that modern Christianity is not the religion followed by the 1st century AD followers who were called Christians. I think he’s mentioned the obvious (when you think about it) fact that the early Christians didn’t a Bible. Here he talks about the diversity of Judaism and how the Christians were a Jewish sect. It shouldn’t be a surprise that religions have adapted to the modern world, last time I checked religious people were as intelligent as atheists. Still, if there is development you have to account for that. I know plenty of people who do, but equally I also know some people who ignore changes, seeing their religion as being an eternal truth. If you have that view then acknowledging that even the idea of religion has changed since ancient times will be a problem.

It’s even more of a problem when you move out of Europe. When the conquistadores arrived in the New World and encountered the native beliefs they saw it as a religious matter. These are supernatural ideas of people who had no contact with Europe for over ten thousand years. Isn’t it odd that concepts developed to describe Abrahamic faiths can so easily be dropped onto other cultures? Are these beliefs religions, and if so how did they come to be?

I can think of two answers. One is that they had a common root. This is possible. Shiela Coulson has argued that there’s evidence of a python cult from 70,000 years ago in Africa. I think her interpretation is problematic, but there’s certainly plenty of evidence of complex thought in Stone Age Africa long before Europe. This evidence will only accumulate as the Eurocentric bias in cognitive archaeology fades. If humans had religious thought before leaving Africa, then it’s no surprise they have it around the world.

The alternative is that there is no common root, and cultures independently developed complex supernatural beliefs. If you believe there was a cognitive Great Leap Forward in Europe then this has an appeal. It could still point to a common root. It’s possible that our common biological and neurological make-up made belief in religion inevitable, but it also means that we should be wary of our cultural blinkers in examining distant peoples. For example if there was a local cognitive watershed it might seem parochial to call it a Great Leap Forward given the history of the term.

Whichever approach you take will influence who you tackle the workings of religion. Is it a cognitive structure that co-evolves with human society, or is it contingent and haphazard in its development? Depending on the scale it operates at, you can make good arguments for both, but that’s also the problem. How do you reconcile these differences of scale? For the trial of Socrates you’d deal with a moment, but is this a chance moment in history where the philosopher annoyed the wrong person, or is it a clash of social structures that are in conflict in ancient Athens? If you’re dealing with the history of ancient Greece in one sweep, an evolutionary approach is attractive, but your historic sources will be static moments preserved by accident. They’re probably not that many in number and carrying biases that we may not be equipped to understand in modern society.

To some extent the tension between change and stasis is a general archaeological problem, but I think it’s acute in studying religion as it’s usually perceived by the people doing it as static and unchanging. Yet ancient societies were all dynamic, so it would seem implausible for religious activity to be static. The question is, is it so dynamic that our concept is a hinderance to understanding supernatural belief in the past? If it is then how do we translate ancient activity, given that we live in the modern world? Is the term ‘ancient religion’ no more (or less) useful than ‘ancient science’?

I have a second problem, but that’ll have to wait till I’ve cleared the next batch of work. It’ll be more difficult to explain because historians will see it as an archaeological problem, and archaeologists as a historian’s problem.

In the meantime you can visit Michael E. Smith’s blog and leave a comment with your own thoughts.

Duty Calls by xkcd

I have some sympathy with alternative archaeologists when it comes to debunking. It’s common to see bloggers debunking their work, but not so much other academics. One reason for that could be that academics, doing their work as a professional job in specialist domains aren’t likely to make as many mistakes as an amateur with a theory that covers a couple of thousand years and the entire globe. But that can only be half the story. Some bloggers don’t criticise other academics at all. Wouldn’t it be a bit odd that academics never make any mistakes? What should you do when they do?

A couple of months ago, I read an odd paper, we’ll call it Paper A, for reasons that might become clear below. Author A made a very simple and basic mathematical error. Something a bit like mixing up a plus and a minus sign and concluding that the Great Pyramid was a hole around 150 metres deep. It wasn’t that bad, but the author thought the conclusions flew in the face of everything known about a site. Still, the mathematics were conclusive, so he had to go with it. There were more errors, but basically the paper was given one big shove in the wrong direction, and the very intelligent and creative author tried to interpret the evidence to fit the mathematical certainty. It was published in Journal A. How do you debunk that?

What I’ve done is submitted a paper of my own pointing out the error. Rather than shred the paper to bits, I’ve shown how anyone can make the mistake of assuming a mathematical certainty. The example I give is an idea I had that, after several months, I worked out was a Bad Idea – even if it looked convincing. I imagine I’ll annoy Author A, but I’ve tried to take the sting out of the rebuttal. It’ll get a brief mention here if it gets published, and I’ll be able to host it on an institutional repository, or possibly the unedited version on arXiv. I decided to submit the rebuttal as a paper and not a blog post here because the claim appeared in Journal A, so that’s the appropriate venue to dispute it in. Because the rebuttal is under peer-review I’m hiding the name and so on to keep it anonymous. Sadly it’s easy to keep anonymous because it’s not made any public splash. This is a shame. It was a clever piece of thinking and had a sexy conclusion. If it had been sound then it would have deserved a lot more public attention.

The reason I bring it up today is that I’ve read a much worse paper today. Paper A had one big mistake and the smaller ones tended to follow from that. Paper B has at least two and I suspect three or more BIG errors. One is that the author has renamed a site. It makes it difficult to track back the prior work on the site, and the bibliography doesn’t mention it. I wouldn’t blame the peer-reviewer if he thought no serious work had been done on the site before this paper. Another problem is the scientific method used in the investigation. Have you ever laid on your back and made animal shapes from the clouds? If have you have, does that make you a zoologist? If you think that’s a bit of a leap, you might have trouble with this paper.

Paper B gives me a problem. I wrote the rebuttal of Paper A, because it was close to the sort of thing I do. It is fairly well sugar-coated and hopefully anyone reading it won’t simply assume author A is an idiot. Paper B is further from what I do, but still around one of my fields. It’s a lot worse.

So now I’m wondering if I should be writing a rebuttal of Paper B, given that my rebuttal of author A’s work wasn’t personal and Paper A was not as bad. I think I can write something original rebutting Paper B, but I can also forsee dragging myself into a series of boilerplate negative papers. It’s not my idea of fun. I think I can pull a mitigating factor out of it, with some effort. An alternative is to stick it up as a research blogging post. It that won’t be read by many people who read the original paper and it’s giving away something that with a little more effort could be a paper on the CV.

Perhaps I think about it a different way. Author A was worth my talent, because Author A had something intelligent to say, even if it was fundamentally flawed. Author B in contrast could be a waste of time. You should insert a five-minute gap here, because while I’m writing this something else has occurred to me. Author B might be a waste of time, but Audience B isn’t. Audience B could have some interesting people in it. Perhaps a rebuttal, if I can get the tone right, could be a way of networking with audience B.

I haven’t decided where I’m going with Paper B yet. If I do write a paper, then I’ll still put up a summary of the problem if there’s no OA option.

Temple Grandin is an interesting person to post regardless of anything else. I first heard of her after reading an interview in NewScientist. I put in an order for Animals in Translation when it came out, that sadly has sat on my shelf since waiting for quality free time for me to read it. Temple Grandin has a radically different view of autism to the common stereotype pushed by the press. I hadn’t realised there were many people who see Autism and Asperger’s as positive aspects to their lives. In the video below Temple Grandin reframes the autistic spectrum as a need for different kinds of minds, which quite literally requires a whole new way of thinking about the mind.

If Grandin is right then this is a major spanner in the works of Evolutionary Psychology. EP as it’s sometimes not so affectionately known, is based on the idea that the human mind is more or less unchanged from the Pleistocene era, so our actions and cognition should be understood with reference to a Palaeolithic world. The video above torpedoes that assumption. First we have to remove the idea that evolution is a linear progression from there to here.

Evolution explained by Nick D. Kim at Strange Matter

Instead we have three kinds of mind according to Temple Grandin, and a social and educational system set up to discriminate in favour of verbal minds. She’s also very clear about the idea of a spectrum, so there could be people at the extremes of all three kinds of mind, and the rest of us in the middle with plastic minds. We get shaped to develop verbal minds because of the primacy of verbal communication and the outcome is a population that develops verbal cognition to the detriment of other forms of thinking, and is unaware that it is doing so. Like she says, it’s natural to assume everyone thinks the way you do. The ability to digest milk is a relatively recent adaptation in humans, but it spread quickly. The advantages verbal cognition could mean that the modern mind is different to non-literate minds. It opens up whole minefield of educational policy that I’m completely unqualified to talk about. It also has implications for SETI because it seems we have been rubbish so far at recognising a different kind of mind in our own species.

The idea that autistic people might be more sensually aware than the average person doesn’t fit the stereotype, unless you think of cute savants. Nonetheless it makes a serious alternative cognitive model. A lot of what I’ve read in SETI is pretty inflexible. It’s still the default position that mathematics could be a universal language. It relies heavily on Platonic ideals in mathematics, and the question of whether or not you need a Plato for a Platonic philosophy. There is the question about the unreasonable effectiveness of mathematics. Sundar Sarukkai has debunked this (PDF) (in my opinion) by showing mathematics is a language. Everything in the universe can be described in English, but no one would say English is unreasonably effective. It’s possible that mathematics appears to work because of an inherent structure in our cognition and not a structure in the universe, a spandrel of a verbal mind. If that’s the case then mathematics is a sign of a kind of mind and we will need to radically rethink what we look for in intelligence to recognise intelligent extra-terrestrial life.

That’s why I think Temple Grandin has an important message for SETI, but equally she also has an important message for Earth. It’s a topic which should be of interest to anyone who’s planning to do some thinking in the future.

Which invader could steal past the Tower of London?

Heritage Key are holding a competition, asking for blog posts about “Which invaders have had the biggest impact on London?” I can’t enter for various reasons, but it’s an interesting question. In the spirit of creatively coming up with the wrong answer, I’m going to go for:

Y. pestis is without doubt the invader who has had the biggest impact, for certain definitions of invader and impact. I think it’s an invader, because it’s thought to have come from the Gobi desert originally. It’s certainly had impact, because no other invader has come close to killing half of London’s population. If you’re wondering which invader killed so many people, it’s thought that Y. pestis in one form or another was the bacterium that caused the Black Death.

It arrived in the UK in 1348. One record is the Grey Friars Chronicle, which has the best description:

In this year 1348 in Melcombe, in the county of Dorset, a little before the feast of St. John the Baptist, two ships, one of them from Bristol came alongside. One of the sailors had brought with him from Gascony the seeds of the terrible pestilence and through him the men of that town of Melcombe were the first in England to be infected.

In reality it probably came in on several ships from across the channel. News of the plague spread much faster than the plague itself, so Gloucester was able to prepare by shutting the gates of the city. As a plan this would have worked if the rats had been trained to enter the city by the commercial routes. For somewhere like London this was not a remotely plausible strategy, and so the population would have been awaiting what seemed like the judgement of a wrathful god. It arrived in London by autumn of the same year, almost certainly aboard a ship rather than from an overland route.

If you were a killer bug with a penchant for pestilence then 1300s London would have been paradise. Hitching a ride in the gut of a flea, you could have transferred to a human or one of the many millions of rats which thrived in the squalor of the city. The hygiene practices of the time, and I use the word hygiene wholly incorrectly, meant that there was a plentiful supply of fresh rats to incubate a travelling plague. It gave the disease a tremendous longevity, in sad contrast to its many victims. If you measure impact purely in terms of people dead, then it’s hard to find anything with greater impact than Y. pestis, which hung around till 1665. Yet it’s not just death that made Y. pestis London’s greatest invader.

Across Britain a third of the population died. The landscape is littered with what archaeologists call DMVs, Deserted Medieval Villages. You can still see them around today with the occasional church in the middle of nowhere, with no obvious congregation. You can’t remove that many people without something breaking, and in the Middle Ages, this was Feudalism. Before the plague serfs had been tied to their master’s estates. The massive culling of the population by the Black Death increased the value of labourers, and set in motion a series of revolts and uprisings which would eventually end Feudalism.

Another effect was the abandonment of land. This helped place more wealth in hands of the church. This wealth helped fuel the conflicts between church and state in later times. More controversially, it’s also been proposed that agricultural use of land could have affected the climate. Bill Ruddiman has argued that the plague led to reforestation of the land, reducing the carbon concentration of the atmosphere, ultimately leading to cooling in the Little Ice Age. This is not a mainstream idea, but it is taken seriously by many climate researchers and does appear in climate change journals, rather than social sciences journals.

Regardless of the climactic consequences, it’s interesting to ask if the Renaissance would have happened without the Black Death. Some of the social changes were happening before the arrival of the plague, but at the very least Y. pestis amplified them. The removal of so many people from the population wasn’t just a quantative change, it was a qualitative change, because it meant rethinking how people were valued in an economy. The Black Death fuelled social changes in the Late Middle Ages which would eventually blossom as the Renaissance. Still, this is one historical character who might not stay in the past. Y. pestis may yet have a role to play in the future.

If you’re interested in reading more about the arrival of the Black Death as an invasion, there’s a very readable chapter in Benedictow’s book The Black Death, 1346-1353: the complete history available in Google Books.

“When one considers that Wagner’s father died of typhoid just six months after the future composer’s birth, it is no exaggeration to say that it is likely that Richard Wagner’s contribution to music would not have occurred without the homeopathic treatment he received.”

(187/365) Leech. Photo (cc) Sarah G... from her Quacks and Cures set

This is an exercise in stating the obvious but, like a lot of homeopathy, it’s so obvious that it’s easily overlooked. I’ve spotted what seems to be a flaw in professional homeopathy. Now a lot of people will point out that homeopathy is utter nonsense because the doses are so diluted that you wouldn’t find a molecule of active ingredient, even if you had enough homeopathic medicine to fill replace the oceans of the world. Some people think the implausibility of extreme dilution matters. These are the kind of people who think that just because an idea is demonstrably false, that means it isn’t true, I’d like to ignore them for now. Let’s say, for the sake of argument, homeopathy does work. I’m keeping an open mind. I don’t know why or how it works, I’ll just accept that it does for the moment. Why would I want to do that?

Well, it’s because Dana Ullman has put up an amazing article at the Huffington Post: 19th Century Musical Geniuses Who Loved Homeopathy. At first I wasn’t sure what expertise 19th century musical geniuses had when dealing with 21st century medical claims. The idea made about as much sense to me as ‘Renaissance Sculptors and their insights into Quantum Mechanics’. It didn’t help that Dana Ullman was a bit too effusive in his writing. The claim “…[I]t is no exaggeration to say that it is likely that Richard Wagner’s contribution to music would not have occurred without the homeopathic treatment he received,” set me thinking.

Typhoid is a nasty disease, but I’ll admit I don’t know how nasty. So I looked it up.

Left untreated the mortality rate for Typhoid is 12-30% for an untreated illness. If you believe in homeopathy then it may have cured Wagner, but the survival rate is high enough that it’s likely he would have survived anyway. Wagner’s survival doesn’t contradict the possibility homeopathy works, but that’s not so emphatic as Ullman’s claim. Survival rates are considerably better with treatment. In Chicago during the Typhoid epidemic of 1891, the mortality rate peaked at almost 0.2% of the population. It might not sound a lot, but it’s a major public health hazard. It means there’s a good chance someone in your neighbourhood could die of it. Still, if the same could be said of Wagner, then a 99.8% chance of surviving typhoid by luck hardly makes homeopathy the likely cause. So what were Wagner’s chances?

Typhoid is spread by a bacterium, which you can fight – if you have a theory of germs. Germ theory didn’t really start till the mid 1800s. In the 1840s Ignaz Semmelweis reduced the number of deaths associated with childbirth by getting to doctors to wash their hands between performing autopsies and delivering babies. During the cholera outbreak of 1854 in London. John Snow was able to show how the disease was transmitted from an infected pump. In the 1860s Pasteur developed germ theory by examining, among other things, the fermentation process of wine. You can’t apply modern survival rates to Wagner’s time, because medicines and knowledge have improved since then. Wagner had typhoid in 1839, before anyone knew about germs. That would suggest a higher mortality rate was likely, closer to 20% than 2%, but it’s still an exaggeration to say that homeopathy was likely to have saved Wagner’s life. It’s possible that neither homeopathy nor medicine was much help at the time.

This is what makes Ullman’s claims interesting. He pulls evidence from a very different era in the history of medicine into a modern context. That doesn’t work for medicine.

Science has radically altered since Wagner’s time. If Semmelweis or Snow were brought into 2009, their knowledge wouldn’t be of much use to medicine. They’d have to relearn medicine because there’s been an improvement in treatment with antibiotics, anti-virals and hygiene. There are identifiable mechanisms for the transmission of bacteria and a large number of methods for identifying if they’re present and what type they are.

In contrast Samuel Hahnemann, the inventor of homeopathy, would have no trouble setting himself up as a homeopath, Homeopathy still has no effective mechanism. Some people chunter on about nanodoses, others quantum effects and others still memory of water but none has been demonstrated with any success. This doesn’t matter if homeopathy works, but the sting is that no homeopathic treatments are demonstrably better than their successors. If homeopathy works, you’re still stuck with 1800s technology. The treatments and methods proposed by Hahnemann in the early 1800s remain just as effective as modern treatments.

That’s why Wagner matters. Whatever treatment Wagner got is still state of the art technology as far as homeopathy goes. It’s like medicine never got further than leeches. In fact that leech at the top of the page is positively hi-tech as leeches were still used to an extent into the late 1800s. When one considers that Dana Ullman is pulling 19th century anecdotes to support modern homeopathy, it is no exaggeration to say that it is likely that he’s pointing out that homeopathy is no better now that it was then.

Thankfully this is a simple post to refute. All a homeopath would have to do is show a reliable study demonstrating modern homeopathic medicines for treating Typhoid are better than those used by Dr Prutzer, the homeopath who treated Wagner.

If it looks like a duck, quacks like a duck and you think it's a duck, then maybe you're just not being open-minded enough. Photo (cc) RealEstateZebra

I sent an email to the British Chiropractic Association’s enquiries email account recently.

Dear BCA,

I read with interest that the use of manipulation is documented ‘as far back as 2700-1500 BC in China and Greece.‘ Could you point me to the documentation for Greece? I’m researching the use of ancient history in justifications for complimentary medicine and I’m not familiar with any such documents. It would be helpful to know about them in my search for other medical texts.

Yours,

Alun Salt

I got a reply. There’s not a lot of evidence.

One possibility is that a fourth century BC tablet from Piraeus might show chiropractic-style treatment. The BCA’s enquiry person kindly linked to a page showing the tablet, which you can find listed as Votive relief to Asclepius, Piraeus Museum, catalogue number 405. As for documentation, I’ll quote: “Greek documents on manipulation from pre-Hippocratic times are more difficult – I don’t know of any (but that does not mean that they do not exist).”

This is interesting because the British Chiropractic Association have quietly announced the ancient history story of the decade. This even beats the Antikythera Mechanism as major news. Here’s the line:

The use of manipulation is documented as far back as 2700-1500 BC in China and Greece.

I’m not an expert on Chinese writing. I thought there was some nationalist vying with the Egyptians as to who had the oldest writing. The books I’ve found give dates of 1200 BC (Bagley 2004, p. 190) or The 14th to 11th centuries BC, with a possible predecessor around the 17th century BC (Norman 1988 p. 58). It would seem that the BCA have access to some previously unknown examples of Chinese writing, but that’s not even half the news.

They also have documentation from Greece in this 2700 BC to 1500 BC band. I don’t know of any 2700 BC writing from Greece, but there’s certainly a script known from around 1800 BC-ish. It’s not actually Greek script. That doesn’t really make an appearance till around the 8th century BC. Earlier than that you have Linear B. Linear B dates from the Mycenaean era. Deciphering Linear B is one of the great stories in ancient history, the bulk of it was done by the mathematician Michael Ventris in the early 1950s. But Linear B dates from the 15th century BC at the very oldest. That’s the 1400s BC, so it can’t be that the British Chiropractic Association is referring to. Still older, there’s Linear A.

Linear A is associated with the Minoan civilisation on Crete. It uses similar symbols to Linear B, but if the symbols have the same sounds, then it is a record of a language unlike any known language. If you want to be a big name ancient history then you could decipher it. Unless you’re too late, because this is what is so staggering about the British Chiropractic Association’s claim. It’s not simply that they may have discovered previously unknown writing in China. It’s the fact they’re able to decipher what these ancient texts means. Often early texts are tax records or similar which only exist in fragments. That these unknown texts should describe skilled medical treatments is stunning. Finding claims like casually announced on the BCA’s website is as amazing as discovering your neighbour has built a time machine in her garden shed.

An alternative, and I hesitate to bring this up because the British Chiropractic Association are notoriously litigious, is that their claim is nonsense. I’m not saying that it is because there are few organisations with the reputation for upright scientific behaviour enjoyed by the British Chiropractic Association. But purely hypothetically, let’s say that these texts didn’t exist. How would those claims get onto the website? The only way I could see would be if someone made them up. Now I’ll admit the word bogus is sailing into view. Such a claim would not be bogus, under English law, because it wouldn’t be intentionally dishonest. It could be written by someone entirely indifferent as to whether or not they were honest.

No, to find a bogus claim, what you’d have to send an email to their organisation, saying that they’re making an odd claim, have a reply back saying they don’t know of any evidence for what they claim and then find they’re still making the same claim on their webpage. That might be bogus because that would mean they are aware it’s a false claim, but still state it anyway. An exact legal opinion on the claim’s bogosity could vary depending on how expensive your lawyer is.

BUT – we know the BCA don’t make bogus claims, there’s a big court case going on defending their reputation. That’s how we know that the BCA must be sitting on one of the biggest archaeological and historical stories of the century.

If you’re interested in what is or is not a bogus claim, you might like to search for Simon Singh on Jack of Kent‘s weblog.

References – ISBN links take you to Worldcat.

Bagley, R.W. (2004) ‘Anyang Writing and the Origin of the Chinese writing system’ in S.D. Houston (editor) The first writing: script invention as history and process. Cambridge University Press . pp 190-249. ISBN 0521838614

Norman, J. (1988) Chinese. Cambridge University Press. ISBN 0521296536

The Antikythera Mechanism. Photo (cc) Tilemahos Efthimiadis.

Some posts take quite a while to write. This is a response to Candy Minx and Martin Rundkvist who were discussing the Antikythera Mechanism back in 2006 (Antikythera, Time, A Reply to the Minx). Candy Minx thought that the Antikythera Mechanism was an expression of what was already known and embedded in a society through things like myth and ritual. Martin thought that the mechanism was far more complex, indeed needlessly complex, for an ancient society and so was something quite different to the folk astronomy of the time. Originally I planned to write a fence-sitting compromise. I thought that Candy Minx was right to an extent, there was no need for a device like this because rituals and folk observation could allow people to time the year as well as they needed. At the same time I thought that Martin was right to point out that the mechanism gave results with far more accuracy than folk astronomy needed, or would even recognise. A different sort of astronomy is visible in the Antikythera Mechanism. I didn’t blog too much about the 2006 paper because I attended a few of Mike Edmunds’ talks on the topic and heard that more would be published, which happened in 2008. Anyhow in my own fluffy and fence-sitting way I’ll now offer my compromise.

Someone with an extraordinary imagination built the Antikythera Mechanism and, if he were alive today, we wouldn’t hesitate to call him a scientist. I don’t know if the designer was in the same league as Newton or Galileo, but he was certainly the equal of Kepler, Copernicus or Brahe. It’s hard to overstate how extraordinary the device described in the 2006 paper is, but I’m going to give it a go.

If you’re the one person who hasn’t heard of the Antikythera Mechanism then Nature have a handy video introduction.

All that remains now is a collection of corroded lumps found off the island of Antikythera. The 2006 paper described what the team discovered after x-raying the lumps to read the hidden inscriptions without prizing apart the device and damaging it. Prior to this paper it was thought that the device could keep track of the Sun and the Moon. This is no small feat.

The Sun would be moving slowly against the background stars, so over the course of a year it would pass through all the signs of the zodiac. The Moon however is more complex. The Moon also moves in front of the background stars, but it only takes about 27 days to do this. It’s called the sidereal period. So you need a couple of gears to drive those two motions. But you wouldn’t really think of the sidereal period as a month. For most people the synodic period, the time between one New Moon and the next or the time between one Full Moon and the next, is a month. This is around 29½ days. Throw in extra gears for driving other displays showing eclipse cycles and it’s clearly a complex device. The original studies found evidence of epicycles, gears mounted on other gears. Add other features like displays for eclipse and lunar cycles on the back and it’s obvious you have a complicated device. The 2006 research showed that in fact it was all a bit more complicated than that.

The Moon’s movement isn’t constant. It speeds up and slows down. This is because its orbit isn’t exactly circular. Instead it’s slightly egg-shaped. The point furthest from the earth is the apogee and the point closest to the Earth is the perigee. When it’s near the apogee it travels slowly, but when it moves closer to the Earth it picks up speed until it passes perigee and then it slows down again. This is called the first lunar anomaly. The difference is noticeable by the naked eye, if you’re willing to make systematic observations. This is all simply explained by Kepler’s Laws of Planetary Motion. There’s small problem. Kepler used ellipses.

You can’t use elliptical gears. The point of gears is that they must have intermeshing teeth. An elliptical gear would lose contact with the driving gear as its axis changed. Instead it seems that the mechanism used two gears, one slightly off-axis from the other. The rotation was connected by a pin-and-slot arrangement, so that the one gear wouldn’t turn at quite the same rate as the other gear. The on-axis gear can then be turned reliably by the drive gears, while the motion of the moon can driven by the off-axis gear. So you have a device that can track the sidereal, synodic and anomalistic months, all while the Earth is spinning round the Sun. If that’s causing your head to spin you might want to skip the next paragraph.

There’s another problem. The lunar anomaly describes the Moon’s travel from one apogee to the next. This apogee is also rotating around the earth. If the apogee is in Aries then two and a bit years later it will be in Cancer, and another two and a bit years to move into Libra until it too has travelled through the zodiac over about nine years. So now we have a device which tracks the Moon around the Earth, and its phases and it’s variable speed and variations in that variability, while also keeping track of the Sun’s position, potential lunar and solar eclipses and intercalation cycles so you know when to stick an extra month in to keep the lunar months in step with the solar year round gears, some mounted slightly off axis to create a pseudo-sinusoidal variation using circular gears to replace ellipses. If you have funny feeling near the back of your head right now, that’s probably your brain trying to crawl out of your ears. The Antikythera Mechanism is insanely complex. Still just because it’s insanely complex, that doesn’t make it scientific.

In fact you can argue about whether or not Science existed in the ancient world. Certainly a lot of elements like testing ideas with experiments didn’t really become popular till after Galileo. On the other hand some natural philosophy of the time was based on observation. There was certainly technology which was the result of applied knowledge. With those kind of provisos a lot of ancient historians would be happy with the idea of ancient science, albeit a science different to post-Renaissance science. In this case, the sheer intense observation and calculation involved in making the Antikythera Mechanism marks it out as a work of ancient science. There’s also another factor which might make it more scientific than artistic.

To some extent the Antikythera Mechanism Research Project have been interested in hanging a name on the device. It was thought to have originated in Rhodes and sunk on its way to Rome, which would have connected it to the home city of Hipparchus, one of the great astronomers of antiquity. The 2008 paper has examined the parapegma on the mechanism and discovered it may be connected to Syracuse, home of Archimedes.

A parapegma is a calendar, usually with holes for sticking a peg into for marking the days. In the case of ancient Greece they’re interesting when they tell you what day of the month it is, because each Greek city had its own set of months. The months were usually named after religious festivals, and this was tied into local politics. That meant having your own calendar was a good way of showing your independence. The best match for the months mentioned on the mechanism is Tauromenion, modern Taormina, in Sicily. This is likely to have shared some months with Syracuse as it was re-settled from there in the fourth-century BC, so Syracuse is a strong possibility for the home of this device. Archimedes is said to have invented a planetarium according to Cicero and is thought to have written a lost book on astronomical devices. However he could not have made this device. Archimedes died in 212 BC. The Antikythera Mechanism is currently thought to date to the second half of the second century BC, but that might change. But it was very likely to have been made after Archimedes death and that’s what makes it scientific.

Art can be collaborative, or it can be personal. Science in contrast is built on cumulative knowledge. The person who invented the gearing did not have to be the person who made the astronomical observations. He didn’t even need to live in the same century as the astronomer. In fact the maker of this device might not have done either. He could have followed a kit and added his own personal touches on the casing. There’s a core to this device which, once expressed, is independent of personal vision. Archimedes didn’t have his own personal Moon which moved in a different way to everyone else’s, while an artist can have a personal interpretation of the Moon.

A reason people might think the Antikythera Mechanism is a work of art is that it’s clearly the result of a lot of imagination. Great art requires imagination, but so too does great science. It requires the kind of imagination that can look at a toolbox full of circles and see ellipses. The kind of imagination that can watch wheels turn within wheels as bodies waltz to the music of the celestial spheres. Another common factor between art and science is that great art can show a new way of looking at the world, and great science does this too. That’s why I disagree with Candy Minx when she says “Science is always playing catch up with the poets.” Science can reveal beauty too, as a visit to the Antikythera Mechanism Research Group‘s homepage would show.

Freeth, T., Bitsakis, Y., Moussas, X., Seiradakis, J., Tselikas, A., Mangou, H., Zafeiropoulou, M., Hadland, R., Bate, D., Ramsey, A., Allen, M., Crawley, A., Hockley, P., Malzbender, T., Gelb, D., Ambrisco, W., & Edmunds, M. (2006). Decoding the ancient Greek astronomical calculator known as the Antikythera Mechanism Nature, 444 (7119), 587-591 DOI: 10.1038/nature05357

Freeth, T., Jones, A., Steele, J., & Bitsakis, Y. (2008). Calendars with Olympiad display and eclipse prediction on the Antikythera Mechanism Nature, 454 (7204), 614-617 DOI: 10.1038/nature07130

Arbor Low on Google Earth

Arbor Low is a Neolithic stone circle and henge in the Peak District. The henge is the bank and ditch arrangement with the bank on the outside and is probably the oldest part of the monument. The current estimate is that it was built around 2500 BC. That’s a date that’s open to a lot of revision as the last published excavation was 1901-2 I think. The stone circle could be as late as 2000 BC.

There’s some odd things at Arbor Low. For example the two entrances mean that the path through the henge runs in the same direction as the Roman Road built over two millennia later. That suggests there’s some pretty deep ideas about movement embedded with the landscape. Excavations at Stonehenge and Durrington Walls have revealed possible timber posts and multiple phases for building, often much earlier and much more complex than previously thought. So why hasn’t anyone taken a mattock to the site for a century? One reason is money, but another can be seen on the east side of the monument.

Some time in the Bronze Age, a chieftain looked at the henge and decided: ‘I’m having that.’ He gathered a lot of earth, quite a bit from the henge bank, and built a round barrow to be buried in. If a tomb is a machine for remembering, then anyone who used the site after that would be reminded that here lay someone who as powerful enough to take one of the biggest, most ancient, sites in the region and make it his. These days we’d call it vandalism and egotism but because it happened over three thousand years ago it’s part of the rich palimpsest of the landscape. Yet his actions made him a target for the future.

The Bronze Age barrow at Arbor Low.

Around the eighteenth and nineteenth century antiquarianism came into vogue. People were becoming aware that there was a long pre-biblical past and one way of finding out about it was to crack open some of the many ancient monuments that littered the landscape. The gentry would go out for a picnic at the weekend and watch, while the hired work would set about a barrow with pick-axes, spades and shovels to see if anything was in it. Which usually meant gold. There might be a few stone tools or bones, but at this time the prehistoric inhabitants were thought of as crude savages. Rather like the people out in the Empire that they were civilising. But some people took more of an interest, and one of these was Thomas Bateman.

Thomas Bateman was born in 1821, and was the son of an amateur archaeologist. His interest grew and he joined the British Archaeological Association in 1843, where he saw how to dig a barrow. The next year he dug almost forty barrows. In total he opened up over a hundred during his life. He used the techniques of his time. That’s why, since Bateman’s excavation, Arbor Low looks like someone thought what the place really needed was a giant earthwork hot-cross bun.

Bateman wasn’t a bad archaeologist for his time. On the contrary, he published his findings. Nevertheless he used the techniques of his time, and digging deep trenches across the barrow were an effective way to get at the artefacts and pottery. Stratigraphy, the idea that the layers of soil overlying a site could reveal some of the context of finds, wasn’t really recognised until the work of Pitt-Rivers and Flinders-Petrie towards the end of the nineteenth century. Bateman’s tragedy is that he had the technology, but he worked before there was a better understanding of how to use it.

Modern archaeologists are aware that not only do ideas change, but so too does the technology. Bateman’s excavations could be called vandalism, but he didn’t have the benefit of hindsight. Archaeology often investigates a site by destroying it, and that can only be done once. Today we have a permanent reminder in the Bronze Age barrow at Arbor Low, which still bears Bateman’s scars.

Foreground: The remains of Bateman's trenches across the barrow.Background: The interior of Arbor Low.