User:Marthynn/Chronophage

The Chronophage (literally time-eater, from Ancient Greek χρόνος (chronos) time, and φαγέω (phageo) to eat) is a clock on the outer wall of Corpus Christi College, Cambridge. It was designed by John Taylor and unveiled by Stephen Hawking on 19 September 2008.

The clock does not have any hands, but displays time by mechanically opening slits in the clock's face, allowing the light of blue LEDs to shine through to viewers. The slits are arranged in three concentric circles, with the innermost counting the hours, the middle counting the minutes and the outermost counting the seconds.

The clock incorporates the world's largest example of the grasshopper escapement mechanism invented by the 18th Century clockmaker John Harrison. However, instead of hiding the mechanism inside the clock, the Chronophage turns the escapement into the clock's primary visual feature, sculpted in the form of a grasshopper or locust.

The Chronophage is entirely mechanically controlled, with electricity used only to power an electric motor which winds up the mechanism, and to power the LEDs. The mechanism includes many unexpected and intricate features; for example, the pendulum briefly stops at apparently irregular intervals, and the locust sculpture moves its mouth and blinks its eye. John 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 protuding 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 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 the gear train slows the action to a realistic pace.

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." Others have described it as "hypnotically beautiful and deeply disturbing".

The Chronophage was engineered by Stewart Huxley and the locust sculpture was make from beaten copper by Matthew Sanderson.

Video of the Chronophage on YouTube: http://www.youtube.com/watch?v=pHO1JTNPPOU