Corpus Clock - Mechanics of The Clock

Mechanics of The Clock

The Corpus Clock is a product of traditional mechanical clockmaking. It features the world's largest grasshopper escapement, a low-friction mechanism for converting pendulum motion into rotational 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 clockmaker John 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" so that the escapement, and the escape wheel it turns, would be his clock's defining feature.

The Corpus Clock's clockwork is entirely mechanically controlled, without any computer programming, and electricity is used only to power a motor, which winds up the mechanism, and to power the blue LEDs 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 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.

The Corpus Clock is expected to be able to run accurately for at least two hundred years. In practice, however, it stopped three times in the first month of its operation.