THE TRINITY CLOCK

 

 
 

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30 Oct 2010 [20:00]
The new steady-state amplitude of the pendulum appears to be 48mrad where it was 55mrad before the gravity arm weights were removed. The going seems to be very steady.
30 Oct 2010 [18:30]
the clock was restarted and adjusted to winter time.
30 Oct 2010 [17:50]
ADJUST: -000 ms/day to 28500 NB new weight configuration due to big changes today. the clock was stopped again to allow the strike to be correctly positioned and for the adjustment for winter time to be be effected.
30 Oct 2010 [17:30]
it was observed that the pendulum amplitude is much greater than it used to be - climbing to over 60mrad. It was decided to remove the two extra weights from the gravity arms - thought to date from the mid eighties when Andrew Huxley had them installed in order to prevent the clock from stopping. It may be, way back then, that the problem all along was rubbing against the pendulum chamber door and impact with the door lock.
30 Oct 2010 [16:30]
the clock was restarted. After such drastic alteration to the pendulum the clock was going at -236 seconds per day so it was necessary to make drastic adjustment to resume steady going. The regulation nut at the bottom of the pendulum was used. First we tried 2 full turns, then 2 more, then 2 more. This was too much. It appears that each full turn increases the going by 45 seconds per day. We then backed off by half a turn, then another half and then one final half turn. This is where we left it.
30 Oct 2010 [15:30]
a new suspension was installed. It has 100mm radius cycloidal cheeks and these may help to regulate the variation of going with amplitude. It has a thinner flexure. The barometric compensator was re-installed. The computer logging system was re-located to the easte end of the clock room, and the associated instrumentation was also moved. It all looks a lot tidier.
30 Oct 2010 [14:30]
The clock was stopped. The pendulum suspension was removed in order to understand why the pendulum moves with a twist. There is accumulated grime in the suspension but no sign of a crack as was suspected. What seems to be happening, though, is that not only has the pendulum has been rubbing on the pendulum-case door it has also been bumping into the door lock. We have removed all obstruction from the pendulum case door and hopefully this will give the pendulum a free swing.
30 Oct 2010 [14:00]
A big day of work planned. Present were Rosie Ayton, Sam Ricketson, Hilary Costello, Tim Gale, Mark Rainer, Graham Newman, Hugh Hunt

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Trinity College, Cambridge 2014