Introduction

The pendulum clock in Trinity College, Cambridge was installed in 1910. It is remarkably accurate, known to be better than 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 at the Engineering Department. A sensor on the pendulum detects the going of the clock, which is compared to the accurate time signal from a GPS receiver.

Here is a graph for the last 30 days of drift (updated every 3 hours):

For an entirely mechanical clock the accuracy is remarkable.

A barometric compensator was installed at clock change - midnight 28 March 2010.

The clock is regulated as infrequently as possible so as to stay within +/- 5 seconds of the correct time. This enables the steady-state physics of the clock to be examined without unnecessary interference.

The black dots ● indicate that there is a comment relating to the time indicated. Blue arrows pointing down ▼ indicate that an adjustment was made to the Going of the clock by removing weights from the pendulum. Red arrows up ▲ indicate addition of weights to speed the clock up.

Comments (see all | edit)

12 May 2013 [11:07]
a top-up wind by Torrin MacKay and David MacKay - all on a Sunday morning
10 May 2013 [10:13]
winding by Svetlana Paterson - who is catalogueing (sp?) the old male-voice music up here in the tower.
03 May 2013 [09:28]
ADJUST: +150 ms/day to 35150
03 May 2013 [09:26]
Help with winding by Alistair Potts - he did the heavy one!
28 Apr 2013 [18:00]
winders @FreddieTapner and Ben Moss @B_R_Moss - both engineers, not revising for their exams!
26 Apr 2013 [07:45]
Is this another bloody pigeon standing on the minute hand at 6.45am this morning when the hand is horizontal? [link]
21 Apr 2013 [18:00]
winding by Ron Holding and Andrew Holding - I hardly had to do anything! We removed the fan and thermometers from the pendulum chute - hence the disturbance to the pendulum.