World - Hawking to unveil world's most accurate clock

The £1 million timepiece with no hands pays tribute to the world’s greatest clockmaker

LONDON: One clock made by the legendary John Harrison, the pioneer of longitude, took 36 years to build and he was still calibrating it when he died at his home in London on March 24, 1776, his 83rd birthday.

The Corpus Clock has been invented and designed by Dr John Taylor for Corpus Christi College Cambridge for the exterior of the college’s new library building. It will be unveiled on September 19 by Prof Stephen Hawking, cosmologist and author of the global bestseller, A Brief History of Time.

Dr Taylor, an inventor and horologist has put £1 million of his own money and five years into the project. “One of my heroes is John Harrison,” he says. Of Harrison’s many innovations, he came up with the ‘grasshopper escapement’, explained Dr Taylor, referring to the device used by Harrison to turn rotational motion into a pendulum motion for timekeeping.

“No one knows how a grasshopper escapement works, so I decided to turn the clock inside out and, instead of making the escape wheel 35 mm across and hidden in the case, it is 1.5 m across and visible with the grasshopper escapement around the outside,” said Dr Taylor.

He calls the new version of the escapement a ‘Chronophage’ (time-eater) - “a fearsome beast which drives the clock, literally “eating away time”.

It is the largest Grasshopper escapement of any clock in the world. The Chronophage “hypnotises the watcher with its perpetual motion, punctuated by an extraordinary repertoire of slow blinks, jaw-snaps and stings from its tail,” says Dr Taylor.

The Corpus Clock, a true mechanical mechanism, which is wound up by an electric motor, has no hands. “It is a new way to show time, with light,” said Dr Taylor. The clock has no digital numbers, either, but instead a series of slits cut into the face, each a tenth of a degree across.

Blue LED lights are arranged behind the slits, and 60 quarter inch lenses, so that when the escape wheel moves, a series of rapidly darting lights runs in concentric circles to mark passing seconds, and pause at the correct hour and minute.

The clock also plays tricks on the observer, seeming occasionally to pause, run unevenly and even go backwards. All this is achieved through mechanics rather than computer programming. Over 100 ball bearings are used in the clock.