52°12.2256′N0°7.0584′E / 52.2037600°N 0.1176400°E /52.2037600; 0.1176400
TheCorpus Clock, also known as theChronophage or theGrasshopper clock, is a large sculpturalclock on the outside of the Taylor Library atCorpus Christi College,University of Cambridge, in England. It is at street level at the junction ofBene't Street andTrumpington Street, looking out overKing's Parade, Cambridge. The clock was conceived and funded byJohn Taylor, analumnus and honorary fellow of the college.
It was officially unveiled to the public on 19 September 2008 by CambridgephysicistStephen Hawking.[1] The clock was named one ofTime's Best Inventions of 2008.[2]
The clock's face is a rippling24-caratgold-platedstainless steel disc, about 1.5 metres (4.9 ft) in diameter. It has no hands or numerals, but displays the time by opening individual slits in the clock face backlit with blueLEDs; these slits are arranged in threeconcentric rings displayinghours,minutes, andseconds.
The dominating visual feature of the clock is a grim-looking metal sculpture of an insectoid creature similar to agrasshopper orlocust. The sculpture is actually the clock'sescapement (see below). Taylor calls this beast the Chronophage (literally "time eater", from theGreekχρόνος [chronos]time, andεφάγον [ephagon]I ate). It moves its mouth, appearing to "eat up" the seconds as they pass, and occasionally it "blinks" in seeming satisfaction. The creature's constant motion produces an eerie grinding sound that suits its task. The hour is tolled by the sound of a chain clanking into a small wooden coffin hidden in the back of the clock.[3]
Below the clock is a Latin inscription from theVulgate1 John 2:17:mundus transit et concupiscentia eius ("the world passeth away, and the lust thereof").
The clock is entirely accurate only once every five minutes.[4] The rest of the time, thependulum may seem to catch or stop, and the lights may lag or, then, race to get ahead. According to Taylor, this erratic motion reflects life's "irregularity".[5]
Conceived as a work of public art, the Chronophage reminds viewers in a dramatic way of the inevitable passing of time. Taylor deliberately designed it to be "terrifying": "Basically I view time as not on your side. He'll eat up every minute of your life, and as soon as one has gone he's salivating for the next." It has been described as "hypnotically beautiful and deeply disturbing".[6]
The clock sits in what used to be the entrance to a bank branch built in 1866 (designed by architectHorace Francis) that originally housed theLondon and County Bank. Corpus redeveloped the site to improve student library provision at the college afterNatWest's lease ended in 2005.
The Corpus Clock is a product of traditional mechanicalclockmaking. It features the world's largestgrasshopper escapement, a low-friction mechanism for converting pendulum motion intorotational motion while at the same time giving back to the pendulum the energy needed to maintain its swing. The grasshopper escapement was an invention of the renowned eighteenth-century clockmakerJohn Harrison, and Taylor intended the Corpus Clock to be a homage to Harrison's work. Since "no one knows how a grasshopper escapement works", Taylor "decided to turn the clock inside out"[7] so that theescapement, and theescape wheel it turns, would be his clock's defining feature.
The Corpus Clock'sclockwork is entirely mechanically controlled, without anycomputer programming, and electricity is used only to power amotor, which winds up the mechanism, and to power the blueLEDs that shine behind the slits in the clock's face. The clock has many unexpected and innovative features; for example, the pendulum briefly stops at apparently irregular intervals, and the Chronophage moves its mouth and blinks its eyes. Taylor explains it as follows:
The gold eyelids travel across the eye and disappear again in an instant; if you are not watching carefully you will not even notice... Sometimes you will even see two blinks in quick succession. The Blink is performed by a hidden spring drive, controlled in the best tradition of seventeenth century clockmakers of London. The spring is coiled up inside a housing that can be seen mounted on the large gearwheel visibly protruding from the bottom of the mechanism. As the huge pendulum below the Clock rocks the Chronophage as he steps round the great escapewheel, each backward and forward movement is used bysprag clutches to wind up the drive spring. A position step prevents the spring from being overwound yet allows the spring to be ready at an instant to drive the Blink. The mechanism is released by a countwheel with semi random spacing so the Blink takes place at any position in the to- and fro- motion of the pendulum. A further countwheel mechanism chooses a single or a double blink whilst the air damper at the top of thegear train slows the action to a realistic pace.[8]
The Corpus Clock is expected to be able to run accurately for at least two hundred years.[9]
Taylor invested five years and £1 million in the Corpus Clock project, and two hundred people, includingengineers,sculptors, scientists,jewellers, andcalligraphers, were involved. The clockwork incorporates six newpatentedinventions. The rippling gold-plated dial was made byexplosive forming–using an explosive charge to press a thin sheet of stainless steel onto a mould underwater at a "secret military research institute in Holland." Stewart Huxley was the design engineer. Sculptor Matthew Sanderson modelled the Chronophage.[6] The graticule, or measuring dish, for the Corpus Clock was designed and created by Alan Meeks of Visitech Design.[10] It was machined in aluminium and silver before being plated with gold andrhodium. Matters relating to the Corpus Clock are dealt with by the Custodian of the Corpus Chronophage Clock, a post currently held by Ewan St. John Smith.[11]
There are sisters to the Corpus Chronophage including the Dragon Chronophage that Taylor installed in the oval mansion Arragon Mooar House he built on theIsle of Man[12] and a further chronophage clock on loan and on display outside bar 1886 in Regent Street in Douglas in the Isle of Man.[citation needed]
The clock is featured in the Hindi moviePaa, the associated music video "Mudi Mudi", and is shown briefly in the third episode of the television seriesZero Hour and in the fifth episode of the Chinese television seriesHere to Heart. The clock is also featured as a plot element in the alternate history novelThe Quantum Curators and the Fabergé Egg by Eva St. John.
