Decoding the Heavens
Page 9
It was 1950, the year that Ellen gave birth to their first child, Linda. For a while Price thought he could measure that too, bringing graph paper to his wife’s bedside and noting down the periodicity of her contractions, so that he might predict the birth-time of the baby. When the infant failed to arrive on time he felt let down and angry. Nature ought to work this way! What kind of god would choose messy randomness over cool, elegant predictability?
Settling in at Cambridge, Price found plenty of role models, not least Joseph Needham, who was the West’s leading expert on the history of Chinese science. Needham also came from a scientific background – he was a biochemist at Cambridge until a young female Chinese student, Lu Gwei-djen, arrived in his lab in the mid-1930s, taught him the language and awakened in him a passion for China. (Half a century later, after his wife died, he finally married her.) Needham taught Price the necessity of knowing everything there was to know about one’s chosen subject. Instead of being content with English sources, as most Western historians were, you had to read everything that had been written, whether it was in German or Chinese or Arabic. And if you didn’t speak Chinese or Arabic, then you had to find someone who did, and work with them until the meaning of each passage became clear.
Price put his training to good use. While sifting through medieval documents in the old library of Peterhouse College looking for references to scientific instruments, he came across a manuscript that struck him as odd. Written scruffily on parchment in dark brown ink, The Equatorie of the Planetis contained instructions for the construction and use of a medieval astronomical device called an equatorium. Based on similar geometric principles to the astrolabe, the rarer and more complicated equatorium showed the positions of the five planets known at the time on its flat disc, as well as those of the Sun, Moon and stars. The manuscript had been in the library since 1542 and had long been attributed to an astronomer called Simon Bredon. But Price noticed references in the tables to astronomical observations made in 1392, and Bredon died in 1372. He couldn’t have written it.
Astronomy texts of the time were generally written in Latin, and Price had only ever seen one other Middle English text on the subject. It was a lesson in the use of the astrolabe by one of the biggest names in medieval literature, Geoffrey Chaucer, the author of The Canterbury Tales. Although best known for his poetry, Chaucer was fascinated by the stars and often worked astrological references into his stories. He probably wrote A Treatise on the Astrolabe – his only known non-literary work – for his son, Lewis. A small footnote hidden in the tables of the equatorium manuscript tempted Price to a conclusion almost as bold as his exponential law. It read ‘radix Chaucer’.
‘Radix’ refers to the reference date that an astronomer uses to compare all of his observations against, hinting that the author of the text and tables could have been none other than Chaucer himself. As he studied the text and analysed the language it used, Price became convinced. Chaucer had indeed written the manuscript as a companion piece to his treatise on the astrolabe, telling the story of the planets’ motions as he narrated the first of his Canterbury Tales. What’s more, the messy corrections suggested that this wasn’t a scribe’s copy – the manuscript was an original in Chaucer’s own hand, the only extensive sample of his writings in existence. It was a sensational claim. But no one has since been able to refute Price’s analysis, leaving experts still arguing today about whether he was right.
This extraordinary find diverted Price yet again, nudging him round one more twist in the path that was to lead to Athens, as he decided to specialise in the history of astronomical instruments. More than any other type of instrument, he was starting to realise that the earliest scientific devices related to the heavens – the equatorium, and before that the astrolabe, and the sundial. These were the devices that would lead him to the beginning of the instrument-makers’ story. They told him that stretching back centuries, people had looked to the dancing lights in the sky and felt the same urge as he did – to measure, to understand, and to predict. He wanted to know where it came from, the knowledge encoded in these instruments, and to trace this will to understand that connects hundreds of generations of human beings who have wondered at the passage of the stars.
Around this time he collaborated with Needham and the Chinese historian Wang Ling on a survey of ancient Chinese astronomical clocks. Their findings appeared in the eminent British science journal Nature in 1956, squeezed between two reports from the frontier of scientific progress: an outline of plans for what turned out to be the first successful crossing of Antarctica, and a summary of a conference at which biochemists excitedly discussed the likely mechanism of DNA, the structure of which James Watson and Francis Crick had stunningly announced in the journal just three years earlier.
Price’s paper, on the other hand, was from another time and another world. It described a Chinese tower from the eleventh century AD. According to a text written from the period by an imperial tutor called Su Sung, the tower housed a huge astronomical clock driven by running water or mercury. The liquid poured into scoops on a big wheel, which each took the same period of time to fill before they weighed enough to trigger a release mechanism and drag the wheel round another step. As well as telling the time, the ornate, ten-metre pagoda displayed the movements of the heavens.
It must have been an awesome sight. On the roof was an armillary sphere: a huge three-dimensional version of an astrolabe’s sky map that would have weighed 20 tons, with a little Earth in the middle and metal rings around it representing the equator, horizon and equinoxes. Just beneath, on a covered platform, sat a great globe marked with the star constellations. The mechanics of the clock drove both around in time with the rotating sky, while within the body of the tower a series of brightly painted puppets were attached to the central revolving shaft, so that they appeared through doors at the front and sounded the time with bells and gongs.
Historians had got the development of clocks all wrong, argued Needham, Price and Ling. The conventional view had been that throughout most of history people told the time using non-mechanical devices such as slow-burning candles, hour glasses, sundials and simple water clocks. Then mechanical clocks appeared out of nowhere across Europe in the thirteenth century – cogs and all – when some genius invented the escapement. The escapement is the bit of a clock that turns the continuous energy from whatever is powering the mechanism (say a falling weight or an unwinding spring) into a series of discrete steps of equal time – the clock’s ‘ticks’. In one simple mechanical escapement, for example, a pendulum weight rocks back and forth in a way that allows a gearwheel driven by the clock to move by one tooth each time the pendulum swings.
The appearance of mechanical clocks in Europe is seen as one of the most crucial moments in the history of technology. The first known examples were extravagant astronomical affairs, which appeared in the thirteenth century and spread throughout the continent during the Renaissance. Like Su Sung’s water clock they displayed the motions of the heavens, telling the time more as an afterthought. It was only later that these clocks were stripped down and miniaturised into something that might be more familiar to us today.
This development was so important because these clockmakers with their skills in precision gearing were crucial in developing the automated devices that ultimately made possible the machinery of the Industrial Revolution (as evidenced by the fact that we still call any sort of automated gearing ‘clockwork’). Take the differential gear, for example. It’s a sophisticated arrangement of gearwheels in which there are two independently driven inputs. These two wheels are connected by a pinion in such a way that their relative motion drives a third wheel at a speed that is related to the difference between the two inputs. It first appeared in Europe in the planetary displays of Renaissance clocks, but then the idea was adopted in textile mills to regulate the speed that cotton threads were wound onto a bobbin, depending on the tension of the strands that were feeding it.
The inv
ention of the differential gear allowed cotton yarn to be mass-produced faster, cheaper and better than it could be by hand, and it revolutionised one of the most economically important industries of the period. Then the arrangement was reversed (allowing one input to drive two independent outputs) for use on a road steam engine, to make the powered wheels more steerable. Eventually it was adopted in automobiles, and is still used today.
Western historians had credited the development of all this to Europe. Exactly where the first clockwork clock came from, and why the earliest ones were so sophisticated (instead of progressing from simple to complicated, as the history of technology is supposed to do) was a mystery. But once clockwork clocks appeared, the foundations for the modern age had been laid.
It was thought that such timepieces then spread from Europe to the rest of the world: Jesuit missionaries took them to China, for example, in the sixteenth and seventeenth centuries. But Western historians had neglected to consult the appropriate Chinese texts. If they had, they would have found that much of the knowledge involved in the mechanical clock was already known in China. These texts contained descriptions of a series of increasingly elaborate astronomical clocks, culminating in Sung’s. It wasn’t mechanically driven, but the wheel nonetheless acted as a kind of escapement, slowing and controlling the continuous flow of the water into a series of regular time steps. And simple gearwork had driven the mannikins and spheres round at the appropriate speed. Historians would need to look much further back for the true origins of clockwork.
The Chaucer work on the equatorium and the Nature paper boosted Price’s career and reputation, not to mention his ego. But during his research he realised that his biggest discovery was yet to come. He had learned about another astronomical object that was far older and far more complex than the equatorium or the Chinese clocktower or indeed than any other known instrument. Price read the papers of Svoronos, Rados and Rehm, and realised that no one had yet come close to unravelling the mystery of the Antikythera mechanism.
It wasn’t clear exactly what the device was, but he could see that the gearwork it contained was more sophisticated than anything else known for more than 1,400 years, at least until the complex astronomical clocks of Medieval Europe. All of the various strands that Price had been tracing back through history – scientific instruments, astronomical knowledge, clockwork – were becoming entwined. And at the head of them all stood the Antikythera mechanism. Price believed that this unique object held the secret to the origins of the entire technical tradition that had led to the first clockwork clocks and then to the advances that ultimately enabled the scientific and industrial revolutions.
The mechanism turned upside down conventional ideas about the scientific legacy of the ancient Greeks. Historians had tended to write them off as clever up to a point, skilled in philosophy and sculpture, but not practically minded. Now, here was evidence that they had been masters in mathematical gearing; that they had built a clockwork computer more than a millennium before anyone else had even dreamed of such a thing. Price realised that the Antikythera mechanism was the oldest surviving trace of a technology that had been crucial to the emergence of the modern world.
Questions bounced about in his head. What had happened to the technology? Could he prove a direct link to modern clocks? How could the Greeks have developed such sophisticated technology without leaving any trace in the historical record? And since they did, what else might they have been capable of? But first, he had to find out more about the mechanism itself.
In 1953 he wrote to Christos Karouzos, the director of the National Archaeological Museum in Athens, to ask for more information. Karouzos duly sent him the most recent photographs of the fragments, which showed that since the publications of the 1920s and 30s, cleaning had revealed several previously hidden features. Price couldn’t understand why such a revolutionary find was largely ignored by historians and archaeologists, and he wrote a couple of articles about it, including one in the British science magazine Discovery, in April 1957.
‘If it is genuine, the Antikythera machine must entail a complete reestimation of ancient Greek technology,’ he urged. ‘Its discovery 55 years ago . . . was as spectacular as if the opening of Tutankhamen’s tomb had revealed the decayed but recognisable parts of an internal combustion engine.’ But it was impossible to glean much detail from the black and white images Karouzos had sent. With so many questions surrounding the mechanism, Price was unable to support his grand claims with anything more than colourful words.
And so, in the summer of 1958, he has come to Athens. He used his considerable charm to persuade Karouzos to let him study the Antikythera fragments directly, and despite a slight bafflement as to why this eccentric British scholar was so keen to see these shabby fragments when the museum held items of much greater importance and beauty, the director merely shrugged and agreed. Now, in a basement storeroom – just a few metres away from the oblivious crowds admiring the Antikythera Youth so glamorously displayed in the museum’s echoing exhibition hall – Price finally comes face to face with another side of ancient Greece, a forgotten strand of invention whose threads he sees woven into everything around him, in every car and bicycle, every clock and calculator.
And like Valerios Staïs before him, he is transfixed by its alien, crumbling appearance. Unlike Staïs, however, Price sees much more of the mechanism’s workings where the external coating of limestone has been scraped away: the big four-spoked gearwheel, that wouldn’t look out of place on a bicycle; the engraved dial, with a graded scale no different to those on the voltmeters that fascinated him as a student; and the smaller wheels behind, not unlike those in the watch on his wrist.
He turns the pieces over and over, looking for any tiny clue that the previous researchers might have missed. Day after scorching hot day Price returns to the museum, always making a beeline for the storeroom. He scrutinises every visible detail of his treasure, and measures it and counts it and notes it down. In particular he checks its ragged edges, trying to work out how the different fragments would have fitted together.
A Greek epigrapher called George Stamires also happened to be in Athens that summer. Price charmed him, too, into helping him to translate the legible parts of the inscriptions, especially the bits that were uncovered by the most recent round of cleaning. Whereas John Svoronos had read 220 letters, and John Theophanidis upped that to about 350, Stamires was able to decipher almost 800. The writing dated to the first century BC.
Price concluded from his measurements that rather than being disparate fragments from a larger mechanism, the pieces all fitted together, meaning that they comprised a greater part of the complete device than had been thought. And he realised that the various dials and plates in the flat fragments had not been squashed together and distorted by the weight of the seawater, as previous scholars had feared. The wheels within the fragments were actually very nearly in their original places – the mechanism had all along been quite flat. It should be possible to start looking at how the individual gearwheels had actually worked, rather than just making vague guesses at the machine’s overall purpose.
Like John Theophanidis, Pericles Rediadis and Albert Rehm before him, Price believed that the mechanism was originally kept in a rectangular wooden case; it would have looked, he imagined, like a well-made eighteenth-century clock. On the front was a big central dial, almost as wide as the case itself, and on the back were two dials of the same width, one above the other. There were traces of small doors on the front and back, made of flat bronze plates. On every remaining surface of the doors and the front and back faces were inscriptions engraved into the bronze.
Price turned his attention to the front dial, which had two scales around its edge. Only the top portion of the dial had survived, but by counting the gradations, he could estimate how many divisions each scale had originally contained.
The inner scale was divided into 12 sections of 30, adding up to 360. In the very top segment of the dial Stamires
was able to make out a complete word: Chelai (ΧΗΛΑΙ), meaning ‘claws’, and the ancient Greek name for the zodiacal constellation of Libra. The claws belonged to a giant scorpion – the body of which forms the next sign, Scorpio – waiting to swallow the Sun as it passes the autumn equinox and into the winter sky. One step to the left on the dial, just two legible letters . . . NO . . . were enough to suggest the name of the preceding sign, Virgo, which the Greeks called Parthenos (‘virgin’), after their goddess Athena. Here, then, was confirmation of what Rediadis had suspected when he saw the word μοιρογνωμóνιον in the machine’s inscriptions half a century earlier. The mechanism’s scale had shown the 360 degrees of the zodiac, with the twelve signs running clockwise around its edge. A pointer edging around this dial would have traced the Sun’s annual journey through the heavens.
The outer ring was divided into 365 segments, with the month name Pachon (ΠΑΧΩΝ), as spotted by Rehm, and the first two letters of Payni (ΠΑ . . .) visible in the surviving top portion. These were two consecutive months of the ancient Greco-Egyptian calendar, which was divided into 12 periods of 30 days each, followed by an extra period of 5 days to make up the 365 days of a year. This scale must have shown the months of the year, again running clockwise round the dial. While the pointer’s position on the inner dial showed the Sun’s path against the background stars, the outer scale would have given the date.
This particular calendar was the favourite of astronomers throughout the Hellenistic world, because every year had exactly the same sequence of months and days, with no adjustment for leap years. This guaranteed that everyone meant the same thing by the same date. But it had the disadvantage of being slightly shorter than the actual solar year, which is 365 and a quarter days long, so it shifted with respect to the seasons by one day every four years (as would our calendar if we didn’t slot in leap years). Accordingly, the outer ring appeared to be rotatable. The user must have been able to move it around by one day every four years, to keep the calendar in sync with the zodiac scale.