Department of Engineering / News / The remarkable accuracy of the Trinity College Clock

Department of Engineering

The remarkable accuracy of the Trinity College Clock

The remarkable accuracy of the Trinity College Clock

Trinity Clock, Cambridge

The pendulum clock in Trinity College, Cambridge was installed in 1910. It is remarkably accurate, known to be better that one second per month, but it was only in 2009 that a system was finally introduced to monitor the "going". The work was done as part of a 4th year MEng project here at the Department of Engineering. A sensor on the pendulum detects the going of the clock, which is compared to the accurate time signal from a GPS receiver. Dr Hugh Hunt is the Keeper of the Clock.

The Trinity Clock in Great Court is a prominent feature of the college. It has a curious way of announcing the hours, once for Trinity and a second time for St John's. It is always within a second or two of the correct time and yet it hardly ever requires adjustment. Does this mean that the mechanism is unaffected by the elements? What about temperature, pressure, humidity? And does the gravitational pull of the moon make any difference? The pendulum on the Trinity Clock has been instrumented to measure period and amplitude to great accuracy. The time is compared with UTC obtained from a GPS receiver. All of this data is streamed continuously to the web at If you thought that the physics of a pendulum was simple, then think again!

Dr Hugh Hunt

Hugh gives talks about the Trinity clock, the next talks are:

  • Friday 26 Feb 2010, 4pm, Lecture Room 5, Engineering Department (Friday Tea Talks)
  • Tuesday 9 March 2010, 6:15pm, Winstanley Lecture Theatre (Trinity College Science Society)
  • Saturday 24 July 2010, 4pm, Winstanley Lecture Theatre, Trinity College (as part of a Turret Clock Tour)

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