The Corpus Clock, also known as the Grasshopper clock, is a large sculptural

clock A clock or a timepiece is a device used to measure and indicate time. The clock is one of the oldest human inventions, meeting the need to measure intervals of time shorter than the natural units such as the day, the lunar month and the ...

at street level on the outside of the Taylor Library at Corpus Christi College,

Cambridge University , mottoeng = Literal: From here, light and sacred draughts. Non literal: From this place, we gain enlightenment and precious knowledge. , established = , other_name = The Chancellor, Masters and Schola ...

, in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

, at the junction of

Bene't Street Bene't Street is a short, historic street in central Cambridge, England, the name being derived from St Benedict. There is a junction with King's Parade to the north and Trumpington Street to the south at the western end of the street. Free S ...

and

Trumpington Street Trumpington Street is a major historic street in central Cambridge, England. At the north end it continues as King's Parade where King's College is located. To the south it continues as Trumpington Road (the A1134), an arterial route out of ...

, looking out over

King's Parade King's Parade is a street in central Cambridge, England.John C. Taylor, an old member of the college. It was officially unveiled to the public on 19 September 2008 by Cambridge

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate caus ...

Stephen Hawking. The clock was named one of ''Time'''s Best Inventions of 2008.

Appearance

The clock's face is a rippling 24-carat

gold-plated Gold plating is a method of depositing a thin layer of gold onto the surface of another metal, most often copper or silver (to make silver-gilt), by chemical or electrochemical plating. This article covers plating methods used in the modern ele ...

stainless steel Stainless steel is an alloy of iron that is resistant to rusting and corrosion. It contains at least 11% chromium and may contain elements such as carbon, other nonmetals and metals to obtain other desired properties. Stainless steel's corros ...

disc, about in diameter. It has no hands or numerals, but displays the time by opening individual slits in the clock face backlit with blue

LEDs A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (cor ...

; these slits are arranged in three concentric rings displaying

hour An hour (symbol: h; also abbreviated hr) is a unit of time conventionally reckoned as of a day and scientifically reckoned between 3,599 and 3,601 seconds, depending on the speed of Earth's rotation. There are 60 minutes in an hour, and 24 ho ...

minute The minute is a unit of time usually equal to (the first sexagesimal fraction) of an hour, or 60 seconds. In the UTC time standard, a minute on rare occasions has 61 seconds, a consequence of leap seconds (there is a provision to insert a nega ...

s, and

second The second (symbol: s) is the unit of time in the International System of Units (SI), historically defined as of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds ...

s. The dominating visual feature of the clock is a grim-looking metal sculpture of an insectoid creature similar to a

grasshopper Grasshoppers are a group of insects belonging to the suborder Caelifera. They are among what is possibly the most ancient living group of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grasshopp ...

locust Locusts (derived from the Vulgar Latin ''locusta'', meaning grasshopper) are various species of short-horned grasshoppers in the family Acrididae that have a swarming phase. These insects are usually solitary, but under certain circumstanc ...

. The sculpture is actually the clock's

escapement An escapement is a mechanical linkage in mechanical watches and clocks that gives impulses to the timekeeping element and periodically releases the gear train to move forward, advancing the clock's hands. The impulse action transfers energy to ...

( see below). Taylor calls this beast the Chronophage (literally "time eater", from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

χρόνος hronos''

time Time is the continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence events, to ...

'', and εφάγον phagon''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. The Chronophage is affectionately known by students variously as "Rosalind", a name coined by the college's Prælector, or "Hopsy". Below the clock is an inscription from the

Vulgate The Vulgate (; also called (Bible in common tongue), ) is a late-4th-century Latin translation of the Bible. The Vulgate is largely the work of Jerome who, in 382, had been commissioned by Pope Damasus I to revise the Gospels u ...

1 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. The rest of the time, the

pendulum A pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the ...

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". 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".

Mechanics of the clock

The Corpus Clock is a product of traditional mechanical

clockmaking A clockmaker is an artisan who makes and/or repairs clocks. Since almost all clocks are now factory-made, most modern clockmakers only repair clocks. Modern clockmakers may be employed by jewellers, antique shops, and places devoted strictly t ...

. It features the world's largest grasshopper escapement, a low-friction mechanism for converting pendulum motion into

rotational motion Rotation, or spin, is the circular movement of an object around a '' central axis''. A two-dimensional rotating object has only one possible central axis and can rotate in either a clockwise or counterclockwise direction. A three-dimensional ...

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 clockmaker

John Harrison John Harrison ( – 24 March 1776) was a self-educated English Carpentry, carpenter and clockmaker who invented the marine chronometer, a long-sought-after device for solving the History of longitude, problem of calculating longitude while at s ...

, 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" so that the

, and the escape wheel it turns, would be his clock's defining feature. The Corpus Clock's

clockwork Clockwork refers to the inner workings of either mechanical devices called clocks and watches (where it is also called the movement) or other mechanisms that work similarly, using a series of gears driven by a spring or weight. A clockwork mec ...

is entirely mechanically controlled, without any

computer programming Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programming involves tasks such as ana ...

, and electricity is used only to power a

motor An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power g ...

, which winds up the mechanism, and to power the blue

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 by
sprag clutch A sprag clutch is a one-way freewheel clutch. It resembles a roller bearing but, instead of cylindrical rollers, non-revolving asymmetric figure-eight shaped sprags, or other elements allowing single direction rotation, are used. When the unit ...
es 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 the
gear train A gear train is a mechanical system formed by mounting gears on a frame so the teeth of the gears engage. Gear teeth are designed to ensure the pitch circles of engaging gears roll on each other without slipping, providing a smooth transmission ...
slows the action to a realistic pace.

The Corpus Clock is expected to be able to run accurately for at least two hundred years.

Funding and realisation

Taylor invested five years and £1 million in the Corpus Clock project, and two hundred people, including

engineers Engineers, as practitioners of engineering, are professionals who invent, design, analyze, build and test machines, complex systems, structures, gadgets and materials to fulfill functional objectives and requirements while considering the limit ...

sculptors Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable ...

, scientists, jewellers, and

calligraphers Calligraphy (from el, link=y, καλλιγραφία) is a visual art related to writing. It is the design and execution of lettering with a pen, ink brush, or other writing instrument. Contemporary calligraphic practice can be defined as "t ...

, were involved. The clockwork incorporates six new

patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A p ...

inventions An invention is a unique or novel device, method, composition, idea or process. An invention may be an improvement upon a machine, product, or process for increasing efficiency or lowering cost. It may also be an entirely new concept. If an i ...

. The rippling gold-plated dial was made by

explosive forming Explosive forming is a metalworking technique in which an explosive charge is used instead of a punch or press. It can be used on materials for which a press setup would be prohibitively large or require an unreasonably high pressure, and is gene ...

–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. The graticule, or measuring dish, for the Corpus Clock was designed and created by Alan Meeks of Visitech Design. It was machined in aluminium and silver before being plated with gold and

rhodium Rhodium is a chemical element with the symbol Rh and atomic number 45. It is a very rare, silvery-white, hard, corrosion-resistant transition metal. It is a noble metal and a member of the platinum group. It has only one naturally occurring isoto ...

. Matters relating to the Corpus Clock are dealt with by the Custodian of the Corpus Chronophage Clock, a post currently held by Dr Ewan St. John Smith.

In popular culture

The clock is featured in the Hindi movie '' Paa'', the associated music video " Mudi Mudi", and is shown briefly in the third episode of the television series '' Zero Hour'' and in the fifth episode of the Chinese television series ''

Here to Heart ''Here to Heart'' () is a 2018 Chinese television series starring Hans Zhang, Janine Chang, Jing Chao and Jenny Zhang. It is based on the novel ''The Warm Chord'' by An Ning. It airs on Hunan TV from April 30 to May 26, 2018. Synopsis Zhan Nanxia ...

''. The clock is also featured as a plot element in the alternate history novel “The Quantum Curators and the Fabergé Egg” by Eva St. John.

References

External links

* {{commons category-inline * John C. Taylo
introduces
his Corpus Clock in a

YouTube YouTube is a global online video platform, online video sharing and social media, social media platform headquartered in San Bruno, California. It was launched on February 14, 2005, by Steve Chen, Chad Hurley, and Jawed Karim. It is owned by ...

video. * Ewan St John Smith
Custodian of the Corpus Clock
in a YouTube video. Corpus Christi College, Cambridge Tourist attractions in Cambridge Individual clocks in England Articles containing video clips 2008 works 2008 sculptures