Cogs to cockroaches

The last few clattering footsteps sulk away into distant corridors and a hush descends upon the small crowd of upturned faces. A man in a priestly gown glances surreptitiously at his watch and shakes it slightly, as if any discrepancy in timing must be the fault of modern quartz or silicon, and nothing to do with the six hundred years that have passed since this spectacle was first set in motion. For a moment there is nothing more to occupy the tourists’ senses than the musty odour of a thousand years of English sweat, incense and death. And then it begins: high on the wall, heralded by a whirr and a clunk, a sullen creature by the name of Jack Blandiver starts to tap out the hour on a bell with his stick. Some metres to the left, a succession of mediaeval knights begin to carousel past each other, one of them being knocked repeatedly from his horse by a lance, apparently having learned nothing from the previous twenty million times this has happened to him. Those in the crowd who can decipher the complex and ornate dial on the wall will see that it is now officially eleven a.m., and the Moon is in its third quarter. For the benefit of any not versed in the art of reading, the cathedral bell also tolls out the time, and then silence returns to my tiny hometown of Wells, in Somerset, as one of the world’s oldest computational machines goes back to counting silently on its fingers.

            Until recently, clockwork like this was almost our only way of carrying out mechanical computations. Simple trains of cogs can easily perform multiplication and division, and with a little ingenuity they can produce a variety of more sophisticated linear transformations, such as the calculation of differences in a differential gearbox. Adding special non-linear elements to the toolkit, such as the ratchet and the escapement, makes far more complex processes possible, for example the self-regulating pendulum clock or the complex calculations (almost) made possible by Charles Babbage’s revolutionary analytical engine.

Copyright © 2004 Cyberlife Research Ltd.
Last modified: 06/04/04