Quotulatiousness

March 27, 2011

Over-analyzing the Bayeux Tapestry

Filed under: France, History, Humour, Technology — Tags: — Nicholas @ 10:39

Chris Mellor looks at the Bayeux Tapestry from a data storage perspective:

The Bayeux Tapestry, the victor’s view of the events, was finished in 1077, ten years after it was begun, making it 934 years old. At 224.3ft long and 1.6ft wide the total surface area is 358.88sq ft.

Our understanding is that the Tapestry features 45 to 48 threads per inch which gives us a resolution approximating 47dpi with a colour depth of 8, ignoring later repairs. Thus, in information terms, the tapestry contains 2.429MB of information, assuming 1-bit per colour, 47dpi, and a 51,678.72 square inch surface area.

From the writing point of view it took ten years for English (Saxon) seamsters, seamstresses or embroiderers to write this 2.429MB of data, which must be some kind of record. Assuming an eight-hour, 350-day working period for these ten years, that implies a write bandwidth of 10.84 bytes/hour; a spectacularly slow data rate in information transfer terms.

What makes it worse is that there were multiple parallel write heads — seamsters or seamstresses — and we could envisage a team of five on average, meaning each write head in this theoretical Bayeux Tapestry archiving model wrote at a rate of 2.168 bytes/per hour (17.344 bits/min). A truly amazingly poor information write bandwidth from our IT viewpoint, but a blur of flickering needles and fingers seen from the embroiderers’ seat.

May 30, 2010

QotD: The first great back-to-the-land experiment

. . . the plundering, the lack of invention, the barbarians and above all Diocletian’s red tape did for Rome in the end. As the empire disintegrated under this bureaucratic burden, at least in the west, money lending at interest stopped and coins ceased to circulate so freely. In the Dark Ages that followed, because free trade became impossible, cities shrank, markets atrophied, merchants disappeared, literacy declined and — crudely speaking — once Goth, Hun and Vandal plundering had run its course, everybody had to go back to being self-sufficient again. Europe de-urbanised. Even Rome and Constantinople fell to a fraction of their former populations. Trade with Egypt and India largely dried up, especially once the Arabs took control of Alexandria, so that not only did oriental imports such as papyrus, spices and silk cease to appear, but those export-oriented plantations in Campania became the plots of subsistence farmers instead. In that sense, the decline of the Roman Empire turned consumer traders back into subsistence peasants. The Dark Ages were a massive experiment in the back-to-the-land hippy lifestyle (without the trust fund): you ground your own corn, sheared your own sheep, cured your own leather and cut your own wood. Any pathetic surplus you generated was confiscated to support a monk, or maybe you could occasionally sell something to buy a metal tool off a part-time blacksmith. Otherwise, subsistence replaced specialization.

Matt Ridley, The Rational Optimist: How Prosperity Evolves, p. 175

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