Monitoring Project - 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. In 2009 a system was installed 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. For an entirely mechanical clock the accuracy is remarkable. Watch the clock strike twelve or hear it strike twelve at Singing from the Towers . Follow @clockkeeper on twitter. Today's and yesterday's weather in Cambridge, including wind. Here is a graph for the last 30 days of drift

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.

date [time GMT]Clock Diary
16 Jan 2017 [22:05:00]winding with Cath Collopy and Bill Collopy  
13 Jan 2017 [18:05:12]winding by Michael Fulcher (Christ Church South Yarra) and Kirsty Ross - not 8-months pregnant this time.  
06 Jan 2017 [11:01:42]winding by Carolyn Wilson, Juliet Harkness (as in @TimandraHarknes) Piers Wilson and Dennis Harkness - after their family party at Corpus where they have a non-clock ...  
05 Jan 2017 [15:14:57]not sure what's happening to the clocklogger PC - I think the hard disc is on its way out. Had to do a hard (push the button for 5 seconds) reboot. Then up came a nasty black windo saying "file system errors" ... "requires manual fsck" so I did fsck /dev/sda1 and answered yes to all the questions. End with exit and it does a reboot.  
01 Jan 2017 [00:00:00]correction due to the leap second - to please Keith Rodgerson!  
30 Dec 2016 [13:31:04]ADJUST: -300ms/day to 40700 see effect of change here [link]  
30 Dec 2016 [13:30:04]winding by Oliver Grigg, Paula Windsor, Adrian Grigg, Jonathan Windsor, Gaenor Jones, Sophia Jones, Neil Jones, Amy Drinkwater, Rachel Bentley Sophie Grigg - serendipitous meeting with past Trinity Engineers  
27 Dec 2016 [21:37:18]winding by Ingo Drewry, Matilda Gomperts Willis, Jasmine Ceccarelli-Drewry, Fabian Gomperts Willis, Imogen Gomperts-Mitchelson and Ian Willis - all well christmas turkey'd.  
20 Dec 2016 [19:53:55]winding by Portia Drewry, Jasmine Ceccarelli-Drewry and Sheila Ceccarelli - all first timers!  
14 Dec 2016 [00:09:41]winding by visiting Melbournians Catherine Hedding and Megan McLaughlin - Catherine did all the hard work!  
10 Dec 2016 [16:50:08]ADJUST: +200ms/day to 41000  
10 Dec 2016 [16:48:43]Winding by Olivia Cutts, Nikki Cutts, Tim Cutts, Doreen Cuerden, Ian Cuerden before the Fairhavens Christmas Concert  
05 Dec 2016 [10:20:22]ADJUST: +200ms/day to 40800  
05 Dec 2016 [10:16:13]winding with Katherine Burchell - soon after her father!  
29 Nov 2016 [12:34:00]reset last_drift  
28 Nov 2016 [17:05:38]winding by Alice Archer - makes a change from Classics!  
21 Nov 2016 [08:01:27]winding with Benat Gurrutxaga-Lerma  
13 Nov 2016 [21:17:44]winding with Gary Walkow  
06 Nov 2016 [12:08:13]ADJUST: -420ms/day to 40600  
06 Nov 2016 [12:05:22]Winding by Eleanor Kornas and Paul Milhau - good exercise before Elly's organ recital this evening!  
05 Nov 2016 [17:36:30]On closer inspection I see [link] that there was weather data being logged (via RS232) very sporadically, so the PC was running. For instance, on Fri 4 Nov there are 31 weather records (instead of the usual 2880 records being one record every 30 seconds). There is a data record in the weather file at 4.18am on Sat 5 Nov and again at 11.24am. Full data (every 30 seconds) resumed at 17:36:30 after the computer restart.  
05 Nov 2016 [17:36:00]Found the computer running but unresponsive. Hard reset, but there's a Ubuntu crash report [link] ... if anyone can figure it out for me! Possibly not important because clocklogger is running fine  
03 Nov 2016 [07:00:00]Not sure what happened here - a power cut? [no, see later comments] The clock was fine - of course. The computer had stopped logging data.  
29 Oct 2016 [23:00:00]Clock change with Graham Steed, Chris Nickolaus, Filip Szczypinski and friends  
22 Oct 2016 [11:36:33]ADJUST: +100ms/day to 41020  
22 Oct 2016 [11:05:00]Clock winding Elizabeth Bourne, Kate Bourne, Jonny Bourne, Tina Queloz, Didier Queloz @didierqueloz - on a sunny saturday  
18 Oct 2016 [11:00:00]GCR 47.7s on upper layer  
16 Oct 2016 [11:31:01]ADJUST: +420ms/day to 40920  
16 Oct 2016 [11:07:46]winding by Cathy Costello, John Costello - managed by Hilary Costello - from Calgary.  
15 Oct 2016 [11:00:00]Great Court Run, four or five 'winners' with a certain degree of corner cutting in evidence ... GCR 47.3s on upper layer, it was decided that 48.5s on lower layer was too slow.  
10 Oct 2016 [21:09:10]Joseph Landman, Rupert Beale @dr_beale_ and Rory Landman, last minute winders  
03 Oct 2016 [09:05:00]winding by Wren Archivist Jonathan Smith - excellent!  
29 Sep 2016 [11:28:24]visit and short wind with Ron Oxburgh after a good discussion about climate change!  
25 Sep 2016 [20:08:58]Winding by Daryl Burchell - first timer!  
18 Sep 2016 [09:43:45]Great to have Lindsay Schusman winding - she's a Big Ben guide. Lots to talk about, and to compare between these two very different but almost identical clocks.  
11 Sep 2016 [17:03:41]Sofia Taylor, Olivia Tidswell, Mark Burrell, Rory Little, Aaron Wienkers, Maximilian Jakobs, Lukasz Kopec, Sarah Garland, Barbara Garland, Filip Szczypinski all sweaty after Zorb football - BA Society friendly, so everybody won  
05 Sep 2016 [14:20:00]Thanks again to Rick Lupton, fixed weatherlogger too. He converted the old file /etc/init/clocklogger (and same for weatherlogger) to the new one /lib/systemd/system/clocklogger.service. Now start it with "sudo systemctl start clocklogger" and check what it's doing with "systemctl status clocklogger". See the logging output with "journalctl -f". Here is the command history that Rick used to make the changes [link]  
05 Sep 2016 [10:20:00]Thanks to Rick Lupton for fixing the problem. Apparently the latest version of Ubuntu doesn't use upstart - it's been replaced with: systemd  
04 Sep 2016 [21:13:20]logging stopped because of upgrade to Ubuntu 16.04.1 - not sure what's gone wrong  
04 Sep 2016 [20:13:20]top-up wind  
02 Sep 2016 [17:09:20]winding by Adeline Klotz, Aaron Wienkers and John Aldridge - we had to fix the Trinity Strike which had stopped early  
26 Aug 2016 [07:05:00]winding by Frank Barker  
19 Aug 2016 [07:05:00]winding by Frank Barker  
16 Aug 2016 [08:42:00]Thanks to Frank Barker for restarting  
16 Aug 2016 [07:42:00]for some reason the clock stopped at 8.39am (7.39am GMT). Surely not a pigeon? See this <[link]> for a 6-minute zoom in of pendulum amplitude (each dot is a 3-second tick). Rather curious that it stopped for about 20 seconds then ran on fine for about 60 seconds and then stopped for good. One theory is that the minute and hour hands interfere with each other as they pass, but these photos [link] [link] taken at 8.44am a few weeks later seem to show that it's OK  
12 Aug 2016 [09:09:59]winding by Meredith Hadfield, Bryony Mountfort and Mantas Kandzezauskas (who actually piked out at the last minute!)  
05 Aug 2016 [09:12:58]winding by Alex Woolgar-Toms  
29 Jul 2016 [13:11:35]winding by Ollie Price matric 1989 and Paul de Panisse after much wranglings over gyroscopic effects  
26 Jul 2016 [16:21:14]ADJUST: +100ms/day to 40500  
23 Jul 2016 [17:04:45]ADJUST: -300ms/day to 40400  
22 Jul 2016 [08:05:00]winding with Alex Woolgar-Toms  
14 Jul 2016 [20:18:26]winding with Ben Ashforth @woollybenguin from Worcestershire - the longest clock-winding journey ever!  
07 Jul 2016 [11:14:44]filming of winding Eugenio Polgovsky - a good excuse not to wind, but he did do the heaviest one!  
07 Jul 2016 [10:55:00]ADJUST: +400ms/day to 40700  
30 Jun 2016 [08:15:00]winding by Alex Woolgar-Toms  
23 Jun 2016 [08:42:57]ADJUST: +600ms/day to 40300 and top up wind.  
19 Jun 2016 [11:09:41]Stopping of the clock to re-align the pendulum optic sensor. Here's a detailed graph of events <[link]> It shows 3 hours' data on Sunday I did a tapping at about 10.30GMT and accidentally touched the pendulum at 10.40, then stopped the pendulum and restarted at 11.10  
19 Jun 2016 [11:00:00]GCR=45.5s on upper level, just after wind  
19 Jun 2016 [10:55:00]Top-up wind by Phil Deakin, Fiona Burke, Joan Lasenby - witnessing a tapping of the pendulum, and accidental touch of the pendulum  
17 Jun 2016 [17:10:00]tapping the pendulum  
15 Jun 2016 [18:00:00]tapping rather more vigorously. A big drop in going! Maybe dislodged a sticking zinc tube in the pendulum, after all my insistence that it wasn't sticking. Maybe we need to take the pendulum apart again.  
15 Jun 2016 [17:30:00]tapping the pendulum always causes s drop in amplitude of swing. Never an increase. Is this a clue? Here's a detailed graph of events <[link]> It's zoomed into 2 hours 5-7pm GMT Note a tapping at about 17:30 caused a step drop in amplitude but a step rise in drift. I'm not sure I understand this. Then a more vigorous tapping at 17:50 caused a drop in amplitude but a step change in going. Is this the zinc tube unsticking?! Then a few minutes later, I don't think I did anything...!  
14 Jun 2016 [22:15:50]changing the suspension would count, in my view, as irreversible, because if it works then who would want to put back the old one? And there's not much point in going to the trouble (and it would be a lot of work) if there's no intention of using it. The barometric compensator is fine because it can be removed in under 5 minutes and the clock is back to its original state. Likewise the teflon tape and graphite powder. The only thing I don't like about the vibrator idea is that it needs a battery power supply. I'm wondering about energy harvesting from the bell flies to charge up a battery...,  
14 Jun 2016 [22:15:40]When I tap it I tap the shaft horizontally back and forth the 0.5mm a couple of times. PTFE is convenient. When I first put it in about a year ago (look at diary comments April to June 2015) it seemed to make a difference. Perhaps the graphite powder too. Not sure which! And for mods like knife edges, etc, they'd have to support the 100kg weight of pendulum. A contact area of 20mm^2 leads to stress of 50MPa so the "knife edges" would be quite thick. I suspect the 19c clock makers would have done it this way if it was a better solution. I also wonder about creating a third lightly damped degree of freedom. Torsion is already coupling with E-W swing, and adding N-S swing at a close frequency will be complex. I'm also reluctant to make irreversible changes to this heritage clock. The idea of a vibrator has crossed my mind, something I'll try if lubrication isn't enough.  
14 Jun 2016 [22:15:30]Some new information: I tapped the pendulum hanger and the pendulum amplitude suddenly reduced. Aha! I think the tower tilt theory is looking stronger. The optic sensor that measures amplitude is mounted on one side of the pendulum shaft (see photo [link] ) It's a top down view, so the sensor is at the bottom of the photo. Note that the pendulum suspension is in vee blocks so that if the tower tilts then it ought to remain swinging in a vertical plane. But friction (which I've tried to reduce with teflon tape and graphite powder) prevents the pendulum from being perfectly vertical. But if it swings out of verticla it also twists. Now, the sensor is off centre so twist registers as a change in amplitiude. So knocking the hanger has made the swing vertical and twist is reduced. In fact from this it is possible to decuce direction of tower tilt, and it's consistent with warming on the sunny side. Getting there!  
14 Jun 2016 [22:15:20]Thermal diffusivity is a useful parameter to describe heat flow through the stone walls. It is about 1e-6 m^2/s. This means that a step change in temperature will take 1 second to reach a depth of 1mm, and 3 days to penetrate half a metre. This is why I'm thinking that a gradual rate of change of temperature (over days) can cause tower tilt.  
14 Jun 2016 [22:15:10]The clock itself is an engineering marvel, accurate to better than 1 second per month. Most of the knots have been combed out, see here for example [link] and what remains are curious glitches that wouldn't even be noticed unless we'd bothered to look. What is great about this is the opportunity to revisit and admire the fabulous achievements of 100s of years of engineers and scientists and to see what little we can contribute ourselves.  
14 Jun 2016 [22:15:00]tapping the pendulum hanger to check if the twist effect is still happenning - and yes it is: [link]  
14 Jun 2016 [22:00:10]The other rather nice thing is that the tapping reducing pendulum amplitude increases going. This seems exactly in accordance with pedulum theory [link] so where does this leave the theory about amplitude increase being casued by the sensor being off centre?  
14 Jun 2016 [22:00:00]OK, so I went up the tower again tonight (with Paul Ashley to watch the St John's fireworks) and gave the pendulum hanger a second tapping. Yet another drop in amplitude (see below). If the theory is correct then as the temperature stabilises the amplitude ought to drop again and tapping should give upward steps. This should satisfy John Hodgson - I don't think economists are very good at making predictions! [link]  
14 Jun 2016 [13:30:00]winding with Sir Jonathan Ive and family and with Roberto Cippolla. Also tapping the pendulum hanger to see if there is a tower tilt effect.  
09 Jun 2016 [07:55:51]Winding with Anna Basaj  
06 Jun 2016 [14:00:30] I have been thinking of sticking of the zinc-steep compensation in the pendulum tube. There are several reasons for NOT thinking it is a sticking zinc tube. 1. It is not sudden - it happened over 8 hours from 10am to 6pm <[link]> The clock normally responds very quickly to even the tiniest of mechanical step changes, eg <[link]> which was an adjustment on 1 May. 2. If the zinc is sticking then we would expect under-compensation, ie slower going as temperature rises. It seems to be faster, so it is the wrong way round. 3. It is a small effect, perhaps 200ms/day fast at the moment. Given that an uncompensated pendulum would be -600ms/day/C then if it were sticking we would expect something bigger 4. stress = E * alpha * dT and for zinc E=100GPa and alpha=30e-6/C , say. Then for a 1C temp rise stress = 3MPa, and with a cross section are of about 1000mm^2 then that is an axial force of 3000N, or 300kg. I do not think there is enough friction to sustain this. When we removed the zinc tube a while back it came out relatively easily. 5. There is a small cyclic stress pulse every 1.5 seconds due to centrifugal force. It s about 2N for a 100kg pendulum bob. This ought to be helping to dislodge sticking. But what can it be???? One clue, perhaps, is that the change occurred during a maximum of "rate of change" of temperature. But why?  
06 Jun 2016 [14:00:20] To give you an idea of what is "normal" then here is data since November. [link] Note that the red and blue arrows indicate intentional adjustments, but that the recent glitch is really one of many, perhaps the most dramatic in recent months. You can change the date back a few years if you want. Also you can look at air pressure, humidity, swing amplitude, etc. Simon mentioned spiders - search for that in comments too. The spider incident was, I think, when a web was spun in the pendulum chamber. the pendulum amplitude reduced which speeds the clock up. But this time the amplitude has not changed, so it is not spiders again - I think.  
06 Jun 2016 [14:00:10] Things like pigeons standing on the hands, wind, snow etc do not have an effect - that is the beauty of the gravity escapement. Likewise lubrication of gears etc. The effect of opening doors - do a search for "the bedmaker effect" - is understood too, after a fashion. The clock dial faces south and it is definitely possible that sunshine has an effect, but not as one would expect. I have a student (from St Johns) this year exploring the effect of warming of the south-facing wall, thermal expansion and therefore tower tilting. The pendulum develops a noticable twist from time to time and this I think is due to tower tilt. It would be good to see if tower tilt, pendulum twist and changes in going are correlated  
06 Jun 2016 [14:00:00]so what has caused this dramatic change in going? [link] Temperature compensation is good. Pressure also (air density affects buoyancy). Humidity is a small effect, humidity in this unheated room is fairly constant. There are step changes, like on 6 June. Still stron is the theory that sunshine on south-facing wall causes thermal expansion and tower tilt. I have a final-year project student (from St Johns !) to measure this effect, strarting October.  
05 Jun 2016 [12:08:58]clock tour for the winner of the Rag Auction: Andrew Sellek, Finn Kristensen, Anthony Wong, Noah Porcelli, Jess Young, Jess Callaghan, Daniel Thompson, Yuen Ng, Toby Henley Smith  
03 Jun 2016 [08:04:49]Winding by Tit hall engineers Isaac Uden, Micheala Chan, Nathan Clark and Joe Myescough from Windfall films!  
28 May 2016 [17:00:00]Winding by Nick Westby and Syuko Kato with Chris Nickolaus  
25 May 2016 [08:44:12]winding after a pedal-punt session with Julia Greenaway @juliacgreenaway, Ed Few, Barnaby Walker and Fiona Holland  
17 May 2016 [22:14:51]after Fairhavens, winding by Pip Matthews @orangepip86 and John Aldridge @jpsaldridge - always good to have help!  
15 May 2016 [11:21:09]visit by Janie Maxwell from Melbourne. She asked lots of great questions!  
10 May 2016 [14:20:41]ADJUST: -410ms/day to 39700 - and a wind  
04 May 2016 [20:49:30]Impromptu winding: Eriks Esenvalds @eriks_esenvalds , Inese Esenvalde, David Baulcombe @dcb40 , Maike Stam, Andrew Crawford, Adam Boise  
01 May 2016 [21:02:49]Great 'night-winders': Imogen Hipkin-Holland, Emma Gee Olmedilla, Carmen Olmedilla Herrero. Andrew Gee, Roberto Cipolla, Yvonne Higgons, Robin Higgons,Stuart Hendry, Alison Hendry, Liesbeth Blom  
01 May 2016 [20:58:21]ADJUST: +500ms/day to 40110 This is the first adjustment since 23 November. It is truly remarkable that the clock has run for 160 days before drifting outside of the +/- 3 seconds leeway that I give it. It seems that the temperature compensation is not perfect. Perhaps I need an extra 30ms/day per degree [link]  
24 Apr 2016 [10:38:27]Excellent winders: Olivia Cutts (youngest ever?), Louis Place, Nikki Cutts, Tim Cutts, Andrew Smith, Ray Morley, Louise Place  
21 Apr 2016 [21:55:46]winding by Trinity College Melbourne Alumni, fearless leader Ken Hinchcliff, Shivaan Bardolia, Nicholas Langford (@njwlangford), Georgina Baker, Taylor Callaghan, Michael Li, Alex Ross, Kirsty Ross  
18 Apr 2016 [09:09:31]winding by Duncan Malthouse-Hobbs @dunk1406 and Andrei Popovici - Trinity Computer lot!  
10 Apr 2016 [16:43:35]winding with help from Chris Nickolaus - lots of chat about tilting towers ...  
03 Apr 2016 [11:08:49]winding by Tamsin Cowley, Ian Cowley and Jasper Cowley with Chris Nickolaus  
01 Apr 2016 [12:00:00]Alex Woolgar-Toms top-up winding with friends  
27 Mar 2016 [00:05:00]clock change by Alex Woolgar-Toms and Chris Nickolaus - many thanks! And a full wind too  
24 Mar 2016 [12:05:00]instructions for the clock change - fiddling a bit with the escapement  
19 Mar 2016 [14:15:00]top up wind  
18 Mar 2016 [18:03:24]Winding by Trinity Catering Duo - Jessica Duck @fitduck and Peter Mezei  
11 Mar 2016 [18:10:04]winding by Chris Nickolaus - on a beautiful spring evening.  
04 Mar 2016 [08:03:26]Early wind by Arsalan Harris  
25 Feb 2016 [21:02:50]winding by David Lavender  
18 Feb 2016 [08:07:05]winding by John Ledger - part of the Logie Baird team!  
10 Feb 2016 [21:33:15]winding by the Combustion Group: Philip Sitte, Anna-Maria Kypraiou, Andrea Giusti, Harsha, Colleen Stuart, Patton Allison, Pedro Magalhaes de Oliveira, Jenni Sidey @jennimsidey  
03 Feb 2016 [18:58:28]winding with Felicity Lamacraft, Celeste Lamacraft, Arrate Molina and Austen Lamacraft - all very excitable inversely proportional to age!  
27 Jan 2016 [17:30:00]winding ably assisted by Terry Black from Windfall Films - all for a documentary about the first television broadcast in 1936. Thanks also to Peter Gauvain behind the camera and Henry Hocking on sound  
20 Jan 2016 [11:23:23]Thanks to Peter Windmill for winding at the last minute - and for correcting the bells that went out of synch  
12 Jan 2016 [23:07:48]winding after Fairhavens with Stephen Watson - Emmanuel College  
05 Jan 2016 [18:11:01]winding by Andy Jude and Hilary Costello - first for 2016  
29 Dec 2015 [17:43:36]Winders: Julian Cooling, Karen Bass and Chris Nickolaus, last wind of 2015.  
22 Dec 2015 [21:27:23]Clock winding by Deah Dhaliwal, Anya Dhaliwal and Sam Dhaliwal, shown the ropes by Hilary Costello - thanks!  
15 Dec 2015 [21:00:00]Winding by Rick Lupton - thanks!  
08 Dec 2015 [22:39:28]after three pints of Pegasus from the Maypole (in own glasses) winding by Ben Sparks @sparksmaths and Seb Falk @seb_falk  
01 Dec 2015 [09:08:34]Nick Denyer girding his loins for essay marking  
30 Nov 2015 [16:13:20]visit by Owen Ryder and Peter Stitt from Cummins Turbo - true mechanical engineers!  
23 Nov 2015 [21:36:40]yet more, from Peterhouse, Trinity and other colleges (Queens' perhaps?) Basil Mustafa, Ethan Silverstone @ethanjdanger, Ciara Norris @ciaranorris18, Fran Penrose @franpenrose, Farzana Huysman @farzanahuysman, Olufolajimi Babasola @folajimi_, Andreas Orphanou, Ruth Augarde, Ben Ferris @benaferris ,  
23 Nov 2015 [21:35:16]ADJUST: -90ms/day to 39610 - on advice from a Queens' student  
16 Nov 2015 [09:16:26]more Part IA Lego engineers! See Yee Tan, Yi Chao Ong, Chen Chun Chai (not clock builders!)  
09 Nov 2015 [09:43:05]Some observations on the effectiveness of the barometric compensator when it was removed for 5 weeks this year. July-Aug (compensator in place): <[link]> Sept-Oct (compensator absent): <[link]> Oct-Nov (compensator reinstated): <[link]>  
08 Nov 2015 [21:33:31]and winding by Emma Gee Olmedilla, Mariana Gee Olmedilla, Carmen Olmedilla Herrero and Andrew Gee  
08 Nov 2015 [21:09:23]Winding by IA lego engineers: Lizzi Hawkins, Elena Rastorgueva, Shrinikesh Arulselvan, Nimesh Patel, Seb Dickson,  
01 Nov 2015 [11:11:24]Winding by German and Danish Othello players: Matthias Berg, Erik Lund Jensen, Anita Raddatz, Ernst Raddatz and Imre Leader  
25 Oct 2015 [00:00:05]Clock Change for end of summer time, thanks to Alex Woolgar-Toms and Chris Nicklaus with Zoran Hadzhiivanov and Jim Minter  
19 Oct 2015 [12:33:20]ADJUST: +200ms/day to 39700 fine tuning after reinstalling barometric compensator. Also winding with Alex Woolgar-Toms who now has instructions for the clock change this weekend.  
15 Oct 2015 [14:23:05]ADJUST: -2300ms/day to 39500 after reinstalling the barocomp, and restarted the clocklogger after reconnecting GPS cable  
15 Oct 2015 [14:22:55]reinstalled the barometric compensator after a period without to see if it is working OK.  
14 Oct 2015 [22:33:40]accidentally pulled out the GPS cable - no data until next day  
14 Oct 2015 [22:33:27]TEA evening winding by CATHY ZHU,Jacky Yang, Guangzhi Sun, Andreas Kattamis, Federica Freddi, Vlad Tomescu, Marijana Vujadinovic, Arsalan Harris, Thomas Burridge, Gordon Hannah, Christopher Langridge, ajit ghosh,BradleyBull Daniel B Zoscha P Chris P, Isabel Vallina Garcia, Dusan Perovic, Dr Steven Whitehouse  
10 Oct 2015 [17:30:13]GCR 47.5s on the day of the Great Court Run. The ITV news report on the Great Court Run and the Clock is here [link] - rather nicely done  
06 Oct 2015 [11:00:30]top-up wind. Also installed a plumb bob to look for tower lean due to sunshine on south wall. Will have to wait for next summer.  
06 Oct 2015 [11:00:20]GCR 47.4 on top layer. Note that the Strikes do 20 strikes per revolution and 156 strikes per day - that is 7.8 turns per day. There are 19 turns on the top layer so the clock should be wound at least 2.4 days before the Run. Thursday at noon is a good time.  
06 Oct 2015 [11:00:10]The clock is 3s fast but I'm in the middle of an experiment to see how the clock runs without the barometric compenasator. Hence the correction by -3 seconds  
01 Oct 2015 [11:00:20]filming with Stuart Leithes - and a top-up wind  
28 Sep 2015 [20:02:56]winding with Peter Dawe - very interesting evening!  
24 Sep 2015 [08:31:37]winding by Fiona Holland @trincollcam - College Communications Officer - we have one at long last!  
20 Sep 2015 [16:40:00]Could this be a pigeon event? [link]  
17 Sep 2015 [14:12:21]wind with Nick Breeze and Luke Parsons. Nothing went wrong, so no litigation required. There is time, says Luke.  
14 Sep 2015 [15:00:00]wind while Paul Ashley takes photos - very nice ones indeed! [link] [link] [link] [link] [link] [link] [link] [link]  
11 Sep 2015 [08:15:23]Winding by College staff today! Jack Mortimer Francesca Baker-Pitman, Kirsty Ross, Karen Wells, Lee Froggatt, James Hobbs, Taylor Reynolds  
06 Sep 2015 [17:04:00]ADJUST: +1800ms/day to 41800 required after removal of barometric compensator  
05 Sep 2015 [14:17:40]ADJUST: +500ms/day to 40000 removed barometric compensator as an experiment to see how well the compensator has been working. In particular, I want to find out if the compensator also affects temperature compensation. For data this summer we seem to have dG/dp=-4ms/day per mbar and dG/dT= 46ms/day per deg [link] . This was worked out by finding the plane of best fit of the G(p,T) graph.  
03 Sep 2015 [21:38:53]top-up wind and in-depth discussion of physics with Dagmar Sternad, David Franklin, Daniel Wolpert and James Talbot from Peterhouse College...  
03 Sep 2015 [17:05:00]ADJUST: +300ms/day to 39500  
03 Sep 2015 [17:00:00]winding with Malcolm Crocker, Ruth Crocker and David Newland  
28 Aug 2015 [11:00:00]12th Cambridge Scouts winding with visitors from 12th Cambridge Scouts Ontario: Scouters: Colin, Hannah, Lisa, Catherine, Katie, Shelley. Scouts: Jonnie, Ben, Beba, Eleanor, Rebekah, Alex, William, Canadians: Sam, Sak, Bryce, Scott, Nathan, Joshua, Nicola, Tristan, Jacob, Connor, Brenden, A.J. followed by a punting trip and tea in Grantchester!  
25 Aug 2015 [19:35:17]The @bbcpm piece is around 5:43pm here [link] Quite fun! @BBCRadio4  
23 Aug 2015 [15:30:00]Julian Cooling (Adelweigian) thoroughly enjoyed the clock. He and Chris Nickolaus had a lengthy discussion on the subject of the Trinity and Hobson Conduits.  
16 Aug 2015 [20:06:30]winding by Ryan Wall, Kerrie Wall, Daniel Flack @drf39 @RWall1993  
10 Aug 2015 [20:00:00]Akemi Matsushima, Kengo Matsushima, Naoto Matsushima, Kanji Matsushima with Chris Nickolaus. Originally from Japan, visiting Cambridge on summer holidays from the US.  
07 Aug 2015 [17:22:51]winding with Dan Larsen  
31 Jul 2015 [08:00:00]winding thanks to Alex Woolgar-Toms  
23 Jul 2015 [21:34:36]Winders from the International Summer Schools: Kong Kit Tung, Lo Hoi Yi Joey, Shi Min Png, Ho Wing Tone Stephanie, William Strider, Isabella-Jane Shah @jbella_z , Cheng Tsz Ching Phoebe, Estefania Vega, Michelle Westlake, Tony Hoskins, Tang Chung Yan Sandy @yan_cy1, Kimba Wong, Carrock Sewell, Susan O Drake, Nanthaya Tisavipat, Rupert Gregg, Ernest Colvin  
21 Jul 2015 [20:41:27]Anne Stillman, Adrian Poole & Murray Stewart very politely in agreement with my Bentley theory ...  
19 Jul 2015 [10:00:00]Winding by Fairhavens after Selene Webb's memorial concert: Carl Rutti, Marie-Louise Rutti, Carys Brown @HistoryCarys, Rupert Beale, Paul Merchant, Howard Leithead  
12 Jul 2015 [11:46:56]Charles Southey, Jane Foster, Simon Foster, Mike Radford, Katharine Radford, Chris Clarke, Rachel Rummery, Gavin Rummery, Stuart King, David Cundy on a tour of the clock  
05 Jul 2015 [21:00:00]Winding with Richard Garrett, Emmanuel Candes, Gaby Candes, Joan Lasenby, Anthony Lasenby, Robert Lasenby, Nick Kingsbury and Chris Nickolaus  
02 Jul 2015 [18:00:00]winding, Chris Nickolaus  
01 Jul 2015 [00:00:00]Leap Second  
28 Jun 2015 [11:30:00]ADJUST: -100ms/day to 39200, also put teflon tape into the pendulum vee, also top-up wind  
27 Jun 2015 [11:00:00]Winding by Annabel Hawkins and Hattie Hawkins, home from Dubai for the summer. Ably assisted by Mike Hawkins and Chris Nickolaus  
25 Jun 2015 [10:05:00]Winders from Cambridge Steiner School: keelan, daniel, adam, yano, indigo, akashi, pip, Emma, Trishna, John MacGinnis, Ute  
25 Jun 2015 [08:51:08]ADJUST: -150ms/day to 39300  
20 Jun 2015 [15:59:21]Visit by Judy Hall from Bendigo  
19 Jun 2015 [13:30:00]GLITCH Christos Kakoutas helped lever up the pendulum to get graphite under the hanger.  
16 Jun 2015 [23:00:00]Trip up the clock tower, and top-up wind, by the winner of the RAG Auction Joe Tomkinson and his friends, Sreya Saha, Tom Rychlik, Lara Booth, Alistair O'Neill, Guus Berkelmans. John Howe, Alex Burgess, Jasmine Girdlestone, Rory Bolsover, Christopher Sear, Lara de Salis  
14 Jun 2015 [11:30:38]GLITCH winding by Neil Hamer and Christos Kakoutas. Also tapped the pendulim hanger to get the graphite powder in - hope to level out the going  
09 Jun 2015 [13:15:00]setting up a method for observing the out-of-plane motion of the pendulum. Bumped the pendulum a couple of times ... [link]  
05 Jun 2015 [11:15:06]Winding with Christina Gladkova, Alex Woolgar-Toms and Rob Baldwin - many thanks!  
05 Jun 2015 [11:00:00]GCR 49.1s on lower layer  
04 Jun 2015 [11:00:00]Up the Tower: Adyseia,Sheldon,Sarah,Kien,Joseph,Nathan,Deronte + Mr Cooksey - Ark All Saints Academy @ArkAllSaints & Eric Lowe - great fun!  
29 May 2015 [17:00:00]Winding by Chris Nickolaus and Zoran Hadzhiivanov - many thanks!  
22 May 2015 [11:39:23]winding by Simon Copley and Rob Baldwin  
15 May 2015 [23:00:00]GCR 46.5s on upper  
15 May 2015 [22:07:20]winding top up by Huw Price, Preston Greene @pregreene, Catrin Campbell-Moore @catrincm, Cecilia Tilli, Man-Sze Li, Sean O hEigeartaigh, Patrick LaVictoire, Stuart Russell, Luke Ding  
14 May 2015 [23:06:38]Winding with Nick Breeze @nickgbreeze after the Ascension Feast  
12 May 2015 [11:05:00]GCR 49.9s on lower  
08 May 2015 [09:01:16]Winding by Atul Bhaskar - my past student, famous for his columns...  
02 May 2015 [21:35:40]Winding after Britten Sinfonia concert by Lily Bacon, Keith McNeil, John Wallwork, Andy Harter, Kate Bull, David Spiegelhalter @d_spiegel  
01 May 2015 [14:45:00]ADJUST: -200ms/day to 39450  
25 Apr 2015 [11:05:00]wind by Stuart Leithes @leithesitv Also tapped the hanger to encourage graphite powder into the vee.  
25 Apr 2015 [11:00:00]GCR = 50.5s at noon on lower layer  
20 Apr 2015 [17:05:00]top-up wind, and graphite powder put into the pendulum hanger vee notch hoping to make a difference to irregular timekeeping. The theory is that sun shining on the south wall of the building causes thermal expansion and tilting of the whole tower. The pendulum then will swing out-of-plane. The graphite will help the pendulum to find the vertical more readily  
16 Apr 2015 [18:10:00]top up by Chris Nickolaus and visiting engineers from Japan Osamu Mochizuki, Mitsu Ogawa and Char Kumagai.  
12 Apr 2015 [12:05:00]winding by Gill De Boer and Matt Henderson, guided by Hilary Costello.  
11 Apr 2015 [15:08:00]winding on Jasmine Drewry's 18th birthday: Corinna Ceccarelli, Dora Gaal, Morna Elliott, Kev Elliott, Jack Elliott @_jackelliott_, lucien hopkinson, skye holland @skyeholland_studio, Ingo Drewry, Giorgio Ceccarelli,  
05 Apr 2015 [11:12:29]ADJUST: +100ms/day to 39650  
05 Apr 2015 [11:03:29]Winding on Easter Sunday by @jasperkoid @ZuziaBulu (Duong Le) and Nigel Goodman  
29 Mar 2015 [00:05:00]GLITCH Clock change for Summer Time done by Chris Nickolaus, Rob Loxley and Kristian Hoffman  
26 Mar 2015 [17:00:00]ADJUST: -100ms/day to 39550 with help from Chris Nickolaus  
24 Mar 2015 [12:19:26]ADJUST: -150ms/day to 39650  
24 Mar 2015 [12:08:37]Visitors from the Oxbridge Academy: Virginia @virgintuh, Amy Jurskis, Justin Lubin, Maria Elena Grimmett, Madison Outlaw @Sent2TheBeast, Blake Clement, Daniel Fischer,Isabella Greene, Patrick Baratta @peanutbaratta , Caitlin Craig-Burke, Alexis Berman @lexiberman, Samantha Spritz @sasspritz,John Klemme @jklemme, Grace Hines, Shoshana Simons, Desi Isaacson, Kella Merlain-Moffatt @kella_nutella , Sarah Ormrod (ICE), Jack Eubanks, Aidan Dermody-McKeen  
22 Mar 2015 [21:02:03]winding with Chris Nickolaus - noticed warm air rising up the weight shaft. Maybe important?  
15 Mar 2015 [15:41:13]ADJUST: +200ms/day to 39800, and winding by Jordan Smith and Mallory Minter  
11 Mar 2015 [23:19:15]ADJUST: +50ms/day to 39600, and winding by @AlbaSotorra Clua , Maia Galarraga, Tony Hoskins - glider out of the attic!  
04 Mar 2015 [13:00:00]winding with Jeremy Sallis from BBC Cambs  
26 Feb 2015 [18:12:40]ADJUST: +150ms/day to 39550, and winding by Peter Windmill and Gwen Francis with @B_R_Moss  
19 Feb 2015 [08:00:00]Winding by Peter Windmill  
12 Feb 2015 [12:05:36]GCR 48.3s noon on upper layer  
12 Feb 2015 [09:30:00]resetting the time and the bells  
12 Feb 2015 [08:30:00]Peter Windmill kindly wound the clock but the bells all need resetting  
12 Feb 2015 [03:30:00]GLITCH Oh dear, I forgot to wind the clock!  
04 Feb 2015 [13:46:47]Winders Keith Lyons, Oskar schortz @os321_oskar, Bianca Carew @Lavender_Barn, Jessica Duck @fitduck  
02 Feb 2015 [12:50:15]ADJUST: -300ms/day to 39400  
28 Jan 2015 [14:25:00]Winding by @Eaterofsun Oliver Morton. He's in Cambridge to talk over #srms15 @SRMscience as he's chairing the Panel [link]  
26 Jan 2015 [14:15:00]GLITCH another top-up wind, and again tapping the pendulum support to see if it affects going.  
23 Jan 2015 [15:05:55]GLITCH top-up wind, and tapping the pendulum support to see if it affects going.  
22 Jan 2015 [00:35:19]winding at this antisocial hour. No takers? No surprise!  
14 Jan 2015 [18:03:00]Winding by Michael Walsh - Trinity Lawyer ... even interested in practical things!  
07 Jan 2015 [12:04:07]Winding with the help of Carole Humphrey after her cooked breakfast in the Masters Lodge ...  
07 Jan 2015 [12:04:00]GCR 49.6s noon on bottom layer  
01 Jan 2015 [16:54:47]thanks to Peter Windmill for the first wind of the New Year  
25 Dec 2014 [12:15:05]Christmas Day winding - Lyudmila Sviderskaya, Vlad Kravchuk, Diana Kravchuk, Tom Lewis @cambwineblogger, Zhanna Lewis, Christina Lewis and Alexander Lewis @ATL_YM - Santa's winding helpers!  
22 Dec 2014 [00:24:05]Winding by the Roberts family: Alex Roberts, Christopher Roberts and Luke Roberts with the help of Mike Roberts and Jane Roberts, under the expert guidance of Hilary Costello.  
14 Dec 2014 [11:52:35]Winding by Marianna Sykopetritou - first timer! GCR = 46.7s noon on upper layer  
09 Dec 2014 [08:00:07]ADJUST: +400ms/day to 39700, winding, and sun shade in window to see if solar effects are important  
04 Dec 2014 [14:24:26]winding with Louis Kovalevsky and Philippe Besnier  
28 Nov 2014 [09:48:02]ADJUST: -500ms/day to 39300 after weather got colder, temp compensation is looking OK, but so keep an eye on it  
28 Nov 2014 [09:45:21]winding: Louise Driffill @ldriffill and Stefan Schaefer - before talking shop about geoengineering!  
23 Nov 2014 [12:10:00]GLITCH three fixes: 1. cleared a spider web (probably not significant) 2. taped up door in pendulum cabinet in room below, may stop draughts 3. increased clearance with optic sensor on pendulum (maybe was making contact?)  
23 Nov 2014 [12:06:59]winding with Stuart Anderson and Ingo Abraham @ingoabraham1 from North Wales (Rhyl) just escaped from Colditz Castle!  
21 Nov 2014 [10:00:00]GLITCH what happened here?! The amplitude dropped dramatically and the going sped up as a result.  
18 Nov 2014 [17:11:14]winding during a Mechanics and Structures supervision: Aniruddh Raghu, Osman Ramadan, Akhass Wasti, Nicholas Kateris, Kevin Wang, James Lewis (not an engineering student!)  
11 Nov 2014 [17:44:15]winding up more than Hugh Hunt with Jawwad Farid @Jawwad_F , Tejal Shanbhag and David Morris @DaveTheTall  
08 Nov 2014 [19:06:47]GLITCH top-up wind and removing baffle on pendulum shaft to see if it makes any difference to temperature control.  
07 Nov 2014 [12:29:29]winding with Adam Keith - thanks!  
07 Nov 2014 [12:00:00]GCR = 48.5s on lower layer  
31 Oct 2014 [09:08:49]Alison Playford from C Great Court did the winding today!  
25 Oct 2014 [23:30:18]Bold decision by John Aldridge (ok, I agreed) that we leave the going slightly fast because the clock seems to be over-compensated for temperature. It is about 100ms/day fast now, but in the cold part of the winter will it turn around for us? We can celebrate with one extra beer if it does!  
25 Oct 2014 [23:25:40]GLITCH clock stopped for the time change with Ben Moss @B_R_Moss, Emily Moss @Aus_Moss, John Aldridge @jpsaldridge, Filip Murar, Dan Safka @RubiCycling, Michal Buran - also did winding  
18 Oct 2014 [13:11:36]I have installed another 256MB of DDR memory on the clock logging computer (yes, it is an old PC!) total is now 760MB. Also installed Konqueror browser because Firefox was very leaky. Also tidied up with apt-get autoremove. Thanks to Per Ola Kristensson for hi s help and advice  
18 Oct 2014 [12:00:00]GCR = 46.5 s on upper layer  
18 Oct 2014 [10:14:17]ADJUST: +200 ms/day to 39800 and winding before the Great Court Run with Isobel Kristensson, Julia Kristensson and Per Ola Kristensson GCR=49s on lower layer (extrapolated from 11am) We will see what it is at noon today  
11 Oct 2014 [16:19:37]top-up wind by Cathy Costello and Sean Costello and Hilary Costello - a heap of Canadian Costellos!  
09 Oct 2014 [09:38:36]The barometric compensator seems to be doing its job really well at the moment! [link]  
08 Oct 2014 [09:23:06]also winding by 3rd-year engineers: Andrei Dobrisan, Sarah Gibson, Natalia Koupanou, Rafal Gaworski, Chen Ma, Jessica Glynn, Michela Gramola, Victor Sun, Nevena Nikolic, Archit Goyal  
08 Oct 2014 [09:23:00] winders: Ananya Miskra, Callum Easton,  
23 Sep 2014 [12:08:50]Top-up wind with Per Ola Kristensson - knows what an escapement is!  
19 Sep 2014 [17:56:17]winding by Chris Bishop and Tom Cook  
12 Sep 2014 [08:00:00]ADJUST: +300 ms/day to 39600, and a top-up wind. Aiming for zero at time-change, midnight Sat 25 Oct. We will see!  
09 Sep 2014 [13:00:00]top-up wind  
08 Sep 2014 [17:00:00]wind, weather station working again!  
08 Sep 2014 [16:43:20]GLITCH Weather logger still out of action  
01 Sep 2014 [13:45:00]GLITCH Barry James from Romax did a top-up wind, weather station still out of action  
30 Aug 2014 [15:00:00]Ipswich branch of the British Horological Institute and the Bury St Edmunds Branch of the Antiquarian Horological Society visited today and did a top-up wind  
27 Aug 2014 [18:00:00]top-up wind with Martin Kyte (MRC LMB) - he wants to build a tower clock with a double 3 legged escapement!  
24 Aug 2014 [17:45:00]GLITCH winding and computer restart, trying to get weatherlogger to work!  
20 Aug 2014 [15:00:00]computer restart, and top-up wind by Hilary Costello  
17 Aug 2014 [19:00:00]GLITCH winding by team Canada: Stephan Bots, Rick Enns, Hilary Costello, Weather logger out of action again...  
14 Aug 2014 [13:01:00]winding by Mark Rainer and (mostly) Daniel Flack - his first time!  
10 Aug 2014 [13:50:03]reset drift correction by restarting clocklogger after changing the value of last_drift from 4.1 to 1.1  
07 Aug 2014 [13:20:00]GLITCH thanks to Mark Rainer for winding, weather station still out of action  
01 Aug 2014 [15:05:19]Winding by Pauline Smith, Senior Porter - her first time!  
01 Aug 2014 [12:16:57] 
27 Jul 2014 [22:00:00]wind, and it is very hot up there!  
25 Jul 2014 [11:30:00]The weather station is back online! many thanks to Rick Lupton for his help, so near to his wedding...  
25 Jul 2014 [10:26:40]GLITCH Weather logger still out of action  
20 Jul 2014 [11:00:00]top-up wind with newly-doctored Stephanie Hill and Simon Jones. Off to Bath.  
20 Jul 2014 [10:56:00]the wear patterns on the quarters strike plate are looking normal [link] . Perhaps just filing it down and greasing it is all that was needed.  
17 Jul 2014 [10:00:00]visit to the clock by TC computer office guys Andrew Cullen and George Townsend, with Rick Lupton showing them how the web-based monitoring system works. They also did a top-up wind.  
16 Jul 2014 [10:00:00]GLITCH Great to have Graham Newman helping with the clock - fixing the Quarters anomaly: from time to time the quarters will skip and the quarter-past does an hour, the half-past does quarter-past etc. Why? A real mystery. [link] , weather station still out of action  
12 Jul 2014 [10:00:00]top-up wind with Malcolm Good. Investigating the Quarters mystery: why does the clock occasionally miss striking quarters?  
10 Jul 2014 [23:33:29]winding after the Geoengineering debate for Cambridge Summer School: Matt Watson (no winding) @matthew__watson, Malcolm Good, Terje Doeviken, @giovannibisutti, isobel smith, Alanna Punch, Katharina Tomaschek who used the last key!  
06 Jul 2014 [11:06:53]GLITCH winding after a boozy Annual Gathering (well done!) by Miss Li Yan, Dr Richard Manns, weather station still out of action  
28 Jun 2014 [23:05:57]GLITCH winding: Beatrice Hunt, Matthew Dougherty, Harriet Kilduff @littlehduff, Hannah Kilduff @hannahkilduff, Louise Dorignon @therightscale, weather station still out of action  
27 Jun 2014 [09:23:31]winding with Dan Safka @Rubicycling  
20 Jun 2014 [16:04:50]GLITCH Linda Bahnweg, Anne Bahnweg @AmagierDesign, Simon Fleischer - Ein Erlebnis in Camridge, ohne die Bayern laufen die Uhren in Cambridge nicht richtig :-), Weather logger still out of action  
19 Jun 2014 [12:00:00]Great to show Carlos Montes from @FoodAcademyUK the clock, and he did a bit of winding...  
18 Jun 2014 [09:05:00]winding by Douglas Buisson - his first time!  
16 Jun 2014 [11:00:00]GCR = 50.4s at noon - on lower layer. Video here [link] - a bit windy and noisy with the fountain splashing  
10 Jun 2014 [20:47:38]winders - winners of the RAG Auction - Anna Elliott, Wilfred Jim Bagnall @wilfbagnall, @TheoCollier, Stefano Novello, Henry Anderson-Elliott, James Tennison, Huw Walters, James Ladbrooke  
08 Jun 2014 [18:15:00]top-up wind  
08 Jun 2014 [18:11:50]ADJUST: -500 ms/day to 39300  
08 Jun 2014 [18:11:40]Jonathan Richman is helping to rebuild the datalogging system - many thanks!  
08 Jun 2014 [11:01:40]GCR = 49.4s at noon - on upper layer. Note that the rehanging (shorter hangers) has slowed down the St Johns strike (repeat). They are both pretty even, Trinity = 18.1s and StJ=18.5s . Lets see what this is like on the lower layer.  
08 Jun 2014 [11:00:00]Singing from the Towers at noon - listen to the clock strike 12 [link] or here on youtube [link]  
07 Jun 2014 [17:00:00]GLITCH winding and the Deans Party with @KateLamble, @joemyerscough, and their friends - names to be supplied (Amy and Simon?), Weather logger still out of action  
06 Jun 2014 [12:00:00]winding: it looks as if the new hangers give 7.5 days less two dongs on the Trinity Strike, so here is the new winding table:  
06 Jun 2014 [11:58:20] -wind before : | 1| 2| 3| 4| 5| 6| 7| 8| 9|10|11|12|
-stops during: |12|12| 2| 3| 4| 5| 6| 7| 8| 9|10|11|
assumes stops 76 strikes beyond 7 days (7 days = 1092 strikes)  
29 May 2014 [23:00:00]Top-up wind after Ascension Feast - Paul Mylrea, Patrick Maxwell, Mark Dunhill  
29 May 2014 [11:01:40]New cheese weights: TC=116kg (TC1=20.5kg TC2-22.7kg TC3-22.7kg TC4-22.2kg TC5-20.3kg) StJ=95kg (StJ1-20.2kg StJ2-22.9kg StJ3-22.1kg StJ4-20.5kg). This will mean the strike is a bit slower.  
29 May 2014 [11:00:00]GLITCH winding, thanks to Hunter Spink, David Vasak and Baskaran Sripathmanathan - followed by installation of new hangers for the weights - thanks to Graham Newman. This should give a couple of hours extra time between windings. Will find out next week.  
21 May 2014 [22:00:00]GLITCH French winders from Artline, Alice Doyard, Pierre Oscar Levy, Mathieu Pansard Weather logger still out of action  
17 May 2014 [22:32:35]Apologies that recent data is not showing. It is being collected, so you will see it all soon!  
14 May 2014 [21:00:00]winding thanks to Sue Edwards (grand daughter of Mr Edwards, Head Porter in the 1960s), Lynn Clift and Gary Clift.  
08 May 2014 [09:00:00]GLITCH Winding thanks to Jessi Lloyd @skimbleshanks - and we also measured up for new weight hangers to get an extra 4 hours running per week. Great! Weather logger still out of action  
30 Apr 2014 [23:00:00]GLITCH winding by Helenka Prochazka and Martin Popiel, weather station still out of action  
24 Apr 2014 [18:00:00]GLITCH winding while Rick Lupton sets up new computer and trial run of new data logging using stereo microphone input. Weather logger still out of action  
19 Apr 2014 [11:00:00]Easter Saturday winders: Marianne Strauss, Ben Strauss, Anne Strauss, Margaret Waring, Kate Hanke, Tom Hanke, Daniel Hanke, Jo Hanke, Barbara Litvine, Alexis Litvine, Laura Litvine, Samuel Litvine, Jorge Grigoleit, Rosie Lintott, Julianne Pigott, Alexandra Sault  
14 Apr 2014 [21:01:40]ADJUST: +300 ms/day to 39800  
14 Apr 2014 [21:00:00]found the computer dead due to power surge earlier in the day. Did a topup wind with Ben Moss @B_R_Moss, after seeing the amazing ISS passby.  
14 Apr 2014 [13:00:00]GLITCH Brownout, and the computer has died. No data for a while....  
13 Apr 2014 [15:08:15] Hector Senior, Elishna ODonovan, Glencora Senior, Elizabeth Senior and Imre Leader all wound very deftly - and we corrected the quarters that were out of sync.  
09 Apr 2014 [14:51:00]winding by Alessendro Cabboi, Alice Cicirello (>2*pi) and Hilary Costello - many thanks!  
02 Apr 2014 [15:40:20]ADJUST: -270 ms/day to 39500 and a top-up wind assisted by Rachel Greene, the new College chaplain  
01 Apr 2014 [13:45:00]I have hung a white sheet in the window to diffuse the sunlight that shines strongly onto the pendulum and mechanism in the afternoons. I hope this will reduce the extremes of temperature and will calm down the fluctuations in going. Also did some winding.  
30 Mar 2014 [00:02:00]ADJUST: -30 ms/day to 39770, clock change for summer time and winding assisted by Anne Bahnweg, Augustine Mzumara @ThisIsGus and Christopher Hicks - big decision to set the clock for the next seven months. Follow it on @clockkeeper  
28 Mar 2014 [15:41:38]ADJUST: -5600 ms/day to 39800 followed by a restart of the computer and updating the National Instruments drivers. A bit of a bother. Would rather set this computer up to use the sound card.  
28 Mar 2014 [13:56:40] Here is a good check that adding the 5000ms/day weight does what it says, speeds the clock up by 5000 ms per day [link] and given that all the weights are scaled in proportion to mass the set we have looks pretty good  
28 Mar 2014 [12:20:00]ADJUST: +5000 ms/day to 45400 in readiness for clock change tomorrow night, I want to start the new season off near zero so that we can test the barometric compensator.  
24 Mar 2014 [20:00:00]ADJUST: -300 ms/day to 40400  
24 Mar 2014 [19:55:00]Twenty cubs did the winding tonight! Thanks to 12th Cambridge Cubs and their leaders. Cubs were Jude, Rebekah, Benji, Harry, Chiara, Eleanor, Timoni, Tomas, Lucas, Alex, Gregor, Henry, Jamie, Bill, Rory, Tom, Johnny, Oliver, Reith, Archie with leaders Jane, Mark and Arusha  
24 Mar 2014 [09:51:06]ADJUST: 4900 ms/day to 40700 after installation of further weights to the barometric compensator. 240g was added to each side, totalling 480g added. This should improve the accuracy of compensation. We shall see ...  
17 Mar 2014 [10:01:05]winders: @justinkohsayshi (Justin Koh), Sally Rowland, Elizabeth Cliffe, ann worley, Dan Safka, Zhi Hao Kok, kaif muhammad borhan tan  
10 Mar 2014 [12:17:12]Thanks to Frank Barker for help with winding today.  
03 Mar 2014 [23:29:38]Fun winding with suitable refreshments - Hamish Drewry, John Byrne, Ben Moss @B_R_Moss, Jessi Lloyd @Engineer_cat, Dan Safka, Filip Murar  
24 Feb 2014 [23:08:55]Winding tonight by a gaggle of mostly Mathmos, Mary Fortune, Sam Tickle, Sean Moss, Alex Chamolly, David Mestel, Oliver Feng, Andrew Carlotti, Ben Barrett  
17 Feb 2014 [22:43:57]Winding by Amy Hewer @Ms_AmyH and Alice Jones @AEMJ from BBC One Show who spring up everywhere, slinking about the College  
15 Feb 2014 [15:30:00]Great winding from Carl Rutti  
08 Feb 2014 [16:00:00] Another delegation of the TEA to see the clock including Michael Gregory, Kadi Liis Saar, Nicole Weckman and Seena Rejal. The door to the roof was opened, very windy. This caused a huge glitch in the going.  
08 Feb 2014 [12:00:00]winding by the Trinity Engineers Association - along with a small correction between the hands (which were 21s ahead) and the pendulum.  
03 Feb 2014 [18:00:00]Ellen Sullivan, Scott Moffat and Hilary Costello did the winding. Enthusiastically! The hands of the clock have ended up 21 seconds ahead. Will be corrected on Saturday.  
28 Jan 2014 [15:45:00]winding, and fixing quarters that were stuck  
25 Jan 2014 [18:00:00]Thanks to Rick Lupton for winding. Curiously the Quarters had stopped by 3.45pm - not sure why...  
18 Jan 2014 [12:32:16]Trinity/Magdalene Engineers winding today Bradley Bull and Fergus Riche - thanks!  
11 Jan 2014 [12:24:00]Michael Burn (daughter is Fran Burn of TC choir) wound the clock he is 72 today, very interested in clocks! Apprentice to Rolex watches, then became a proper HND engineer! Rings at St Mary le Tower in Ipswich - they have a ring of 12.  
06 Jan 2014 [12:00:00]GCR = 44.5s at noon - on upper layer  
04 Jan 2014 [12:22:18]winding - first of the New Year! Paola Pellegrini, Andrea Pertoldeo @Pertoldeo and Ruth Pellegrini.  
02 Jan 2014 [14:55:40]ADJUST: -200 ms/day to 35800  
31 Dec 2013 [18:10:25]Last wind for 2013 done by Alexander Lewis @ATL_YM , Christina Lewis, Zhanna Lewis and Tom Lewis @cambwineblogger - the clock is all ready for 2014 now!  
24 Dec 2013 [16:22:00]thanks to Mark Rainer for winding on xmas eve  
19 Dec 2013 [18:17:04]winding done - check data 21/7/11 to 18/4/12 files like clock2012-03-25.txt and weather2012-03-25.txt  
12 Dec 2013 [12:00:00]winders from DVRO: Andrew McKay, David Hawes, Chris Nash and Hilary Costello. All keen!  
12 Dec 2013 [11:58:20] -wind before : | 1| 2| 3| 4| 5| 6| 7| 8| 9|10|11|12|
-stops during: |10|10|11|11|11|12|12| 2| 5| 6| 8| 9|
assumes stops 52 strikes beyond 7 days (7 days = 1092 strikes)  
05 Dec 2013 [08:57:05]winders First-year engineers before their Mechanics supervision, Zoscha Partos @zoschapartos and Christopher Parmenter  
28 Nov 2013 [08:30:02]Richard de Crespigny (Qantas pilot) and Alexander de Crespigny (Mechatronic engineer) did a great job winding  
24 Nov 2013 [12:07:42]winders today Filip Gokstorp, Simon Gokstorp, Asa Gokstorp, Mats Gokstorp, Sue Budd, Chris Budd, Isabel Adomako Young -  
17 Nov 2013 [12:21:57]top-up wind by Newnham engineers Aurelia Hibbert @AureliaFortune , Amy Livingstone and Jamie Hooper @paedocapybara - doing a Dambusters and Colditz showing tonight!  
16 Nov 2013 [14:05:00]Winding today by Jaana Wilkinson, Elena Loche, Alice Cicirello, Rick Enns and Hilary Costello - many thanks!  
15 Nov 2013 [10:45:00]so what happened at 10.45am on 15 November to cause the clock to go into a decline? There is no obvious change in temperature or pressure or humidity, and the swing amplitude has not changed ...  
12 Nov 2013 [13:07:07]Katy Cherry @missmoomins did a good job winding today  
09 Nov 2013 [12:08:51]Cassandra Pope @cassiekp , Claude Grewal-Sultze, Hannah Critchlow @nakedscientistss and Kate Hamble @katehamble did winding on this wet and grimy day  
07 Nov 2013 [11:19:09]Sue Marchant did a top-up wind this morning - loves machinery!  
05 Nov 2013 [21:40:00]Just for fun. slowed the clock down for a few minutes - by 3000ms/day <[link]>  
05 Nov 2013 [21:35:41]winders Carol Black, Kevin Sim, David Rueda and Chris Morley - all very expert!  
02 Nov 2013 [12:00:00]Winding was done today at noon by Pieter Coulier on his last day in Cambridge with the help of Kevin Crooks, Francesco Battocchio, and Elke Deckers  
27 Oct 2013 [21:51:49]I now have a list of the friends: a substantial team comprised of physicists, engineers and mathematicians! Mike Vella, Matt Henderson, Dave Saxton, Anton Isopoussu and Sam Rabin.  
26 Oct 2013 [23:00:00]GLITCH clock change, thanks to Hilary Costello and friends (see list later). It is great to see the pendulum amplutude decay [link] exactly as theory predicts [link]  
23 Oct 2013 [14:00:00]Thanks to Rick Lupton for getting the computer going again (very relieved, it looked pretty bad when he stopped it yesterday) I am no expert in Linux (OpenSuse) so I need clever people to be involved...  
23 Oct 2013 [07:10:00]removed the pigeon wire for maintenance - ie making a stronger one (bloody eavy, em pidgins!) Great fun going up on the cherry picker  
22 Oct 2013 [17:05:18]Computer restart - unsuccessful! No data logging until it is fixed - something to do with NI drivers ...  
22 Oct 2013 [16:06:40]winding by Keeret Riat and David Harber - enthusiastic!  
19 Oct 2013 [13:48:09]Winders Eric Freyfogle, Jane Freyfogle from Illinois and Kevin Gray, Dean of College on this the day of the Great Court Run  
17 Oct 2013 [10:05:00]corrected the glitch - the clock was 93 seconds slow ... needs to be right for Saturday, the Great Court Run  
15 Oct 2013 [12:20:00]Winders (and glitch makers!) Len Howlett and Mark Rainer  
08 Oct 2013 [11:14:19]Winding by Chris Rosier - hot work, eh?!  
08 Oct 2013 [11:00:00]GCR = 45.9s at noon - on lower layer  
06 Oct 2013 [23:00:00]GCR = 45.6s at midnight - on lower layer  
01 Oct 2013 [12:34:24]ADJUST: 400 ms/day to 36000  
01 Oct 2013 [12:32:40]Winders from the Catering Department - Jessica Duck, Sarah Walsh, Les Fry (unlikely to fall asleep this afternoon, I hope) and Pieter Coulier (the jelly man)  
24 Sep 2013 [11:30:35]Great winding by Matthew Henderson, ably supervised by Hilary Costello  
17 Sep 2013 [13:00:00]Quarter bells adjusted (thanks to Graham Newman) so now they go Dinggg Donggg instead of dng Donggg (like an old man with a limp) Also winding done.  
16 Sep 2013 [08:40:00]data uploading is working again. Some adjustments to the FTP service on the main website were needed.  
14 Sep 2013 [21:00:00]computer checked (data not uploading) all running OK - perhaps a change on the central server? clock wound  
08 Sep 2013 [12:00:00]Good to see Maarten Beckers back, winding under the watchful eye of Pieter Coulier...  
06 Sep 2013 [12:15:08]Winding thanks to John Lonsdale and Moya Lonsdale - enthusiastically interested in the history, which is fascinating I admit  
06 Sep 2013 [11:00:00]GCR = 44.6s on lower layer  
30 Aug 2013 [22:40:36]Pretty remarkable that for more than 2 months over the summer there has been barely half a second drift [link]  
30 Aug 2013 [12:00:00]thanks to winders Alice Cicirello, Pieter Coulier and Hilary Costello - very multinational! Alice managed 4-pi worth of winding  
23 Aug 2013 [12:01:57]Great day for Lucy Beharrell and Will Beharrell on their 9th wedding anniversary. Anyone listening would have heard the clock strike 9 - at 1pm! Thanks for winding too .  
22 Aug 2013 [11:06:45]GCR=43.9s (midnight last night was 43.8s) - looking good. Note that speed change due to diameter change on second layer is sqrt(140mm/135mm) = 1.019 (first layer diameter = 135mm, wire diameter = 5mm, drag goes as speed squared) so we expect perhaps GCR=44.7s later on as the weights descend. Air density effects, summer vs winter, max density on a dry cold day is 1.27 and min density on a hot humid day 1.14 is see [link] so the range is sqrt(1.27/1.14)=1.055 and that is about a 2.4s range from extremes.  
21 Aug 2013 [18:37:36] full wind as well, Imogen Newman watching on ... holding the tubes.  
21 Aug 2013 [18:37:03]Note cheese weights: TC1-20.5kg TC2-22.7kg TC3-22.7kg TC4-22.2kg TC5-20.3kg + two new ones 21.5kg + 21.5kg StJ1-20.2kg StJ2-22.9kg StJ3-22.1kg StJ4-20.5kg + two new ones 21.1kg + 21.7kg. Extra weights are thick-2.4kg and thin-0.7kg  
21 Aug 2013 [18:33:42]work with Graham Newman today slowing down the strike - TC strike 159kg to 128kg (5 original cheeses + 5 thicks), StJ strike 137kg to 110kg (4 original cheeses + 5 thicks + 5 thins) Let us see what happens.  
17 Aug 2013 [11:11:32]Jonnie Hunt, Mael Thomas, Sandy Hunt, Qian Wang did a great job winding. Noon going+Strike time GCR = 40.6s - a bit too fast (note GCR stands for Great Court Run - historically it is around 44s, but changes made in 2007 need to be put right)).  
11 Aug 2013 [11:24:27]Monique Degimbe, Albert Renders, Annick Renders, Jean-Pierre Coulier hebben de klok opgewonden tijdens hun bezoek aan Pieter! (full marks to anyone who can read that...)  
07 Aug 2013 [14:13:52]the warm weather has made the first bell of the quarters not sound. We fixed that by a bit of deft metal bending - as I say, always use the right tool for the job (my feet).  
07 Aug 2013 [14:12:05]doing a bit of recording for The Naked Scientists @nakedscientists with Dominic Ford @dcf21 - a good excuse to do some winding! By the way, what is the terminal velocity of a penny?  
04 Aug 2013 [11:59:15]Thanks Hilary Costello for winding - good Sunday exercise!  
28 Jul 2013 [13:05:14]Winding thanks Pieter Coulier, though jet lagged.  
21 Jul 2013 [11:17:58]Winders today Matilda Sleigh, Elliott Sleigh, Sarah Lavelle, James Sleigh - hot work!  
14 Jul 2013 [13:00:01]Thanks to Rick Lupton for winding - even hotter. Fantastic temperature compensation in this rising heat [link]  
07 Jul 2013 [11:05:39]top up wind par Lucie Delpeuch et Jonnie Hunt - hot work  
06 Jul 2013 [11:17:39]Great that Pieter Coulier has learnt the ropes and is now on my list of winders!  
29 Jun 2013 [10:36:38] winding after Sam Coxs graduation yesterday. Also with Steve Cox, Penny Cox and Patrick Cox - who will work our a Raspberry Pi app for me!  
26 Jun 2013 [09:24:38]also winding (and playing BOGIES) Anna Towriss, Ute Towriss, Ed Few, Paul Joyce, Rupert Gatti Caz King  
26 Jun 2013 [09:24:37]The first game of BOGIES ever in the clock tower! benjamin rose, mossy forbes, jennifer leek, hester stewart, joe evans Great fun!  
26 Jun 2013 [09:24:36]ADJUST: +300 ms/day to 35600  
24 Jun 2013 [21:17:06]SPICE meeting today, so winders were James Talbot, Matt Causier, Clare Causier, Ming Jin Tang and others Andy Elson, Simon Driscoll, Matt Watson, Tanya Gray, Hilary Costello, Scott Osprey, Don Grainger, Rob McPheat, Tony Cox,James McGregor, Francis Pope, Dan Peters  
23 Jun 2013 [17:17:17]ADJUST: -500 ms/day to 35300 - quite why this acceleration has happened is a puzzle.  
18 Jun 2013 [22:13:52]Rag winner Bethany Craik and her friends, Thomas Rychlik, Jake Lishman, Guus Berkelmans, Jamie Balcombe, John Howe, Cameron Ford, Matthew Varnam. And MathsJammers @MathsJam, Interesting to see this old technology working so well. John Shanks. Matthew Harbage, Edward Cree.  
16 Jun 2013 [16:27:43]Enjoying the behind the clock tour! @katelamble @joemyerscough @katlay @kayaburgess - a good winding team.  
09 Jun 2013 [19:08:58]Michael Strasser @pharsicle, Lou Strasser, Jill Graham enthusiastic winders after two evensongs and a trip up Great St Mary, now off to see singing on the river ...  
06 Jun 2013 [15:12:50]ADJUST: -250 ms/day to 35800  
06 Jun 2013 [15:12:49]James Appleton @jamesappleton86 Laurie Cuthbert @trinity1546 and Mary Priddey taking photos!  
02 Jun 2013 [19:10:00]top-up wind. Unjamming of the quarters (over-wound on Friday - I did not think it was possible to over-wind!)  
31 May 2013 [11:00:00]winding thanks to Hilary Costello, Danielle Wong and Chris Lloyd from Canada.  
25 May 2013 [15:03:59]winding ably assisted by Lydia Marston-Blaauw and cousin Christopher Hunt, visiting from Vancouver BC. Lydia found one extra step that she did not think was there!  
19 May 2013 [09:57:50]winding by Piotr Grudzien, Danielle Broadfoot, Raphael Lemahieu, Marek Romanowicz @MarekRomanowicz, Ben Moss @B_R_Moss - makes it easy for me!  
12 May 2013 [10:07:38]a top-up wind by Torrin MacKay and David MacKay - all on a Sunday morning  
10 May 2013 [09:13:34]winding by Svetlana Paterson - who is catalogueing (sp?) the old male-voice music up here in the tower.  
03 May 2013 [08:28:37]ADJUST: +150 ms/day to 36050  
03 May 2013 [08:26:40]Help with winding by Alistair Potts - he did the heavy one!  
28 Apr 2013 [17:00:00]winders @FreddieTapner and Ben Moss @B_R_Moss - both engineers, not revising for their exams!  
26 Apr 2013 [06:45:00]Is this another bloody pigeon standing on the minute hand at 6.45am this morning when the hand is horizontal? [link]  
21 Apr 2013 [17:00:00]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.  
14 Apr 2013 [16:00:00]ADJUST: -500 ms/day to 35900, thanks to Hilary Costello - and winders Rick Enns and Maarten Willems from Leuven.  
08 Apr 2013 [16:24:17]winders just now Aryani Sumoondur and Urs Rauwald - saves me all the effort!  
01 Apr 2013 [16:30:00]Winders: Chris Scott on his 60th birthday (wound the lightest weight!), son Alex Scott, Cat Hobart and Mark Claydon - all ably instructed and guided by Rick Lupton and observed by Sarah Claydon, nee Scott. The clock will need winding again next Monday - any volunteers?  
31 Mar 2013 [00:05:00]GLITCH thanks to Rick Lupton for doing the clock change.  
26 Mar 2013 [09:15:00]ADJUST: +1000 ms/day to 36400 further adjustment required after last night meddling about.  
26 Mar 2013 [09:10:00]The fan (sucking the warm air up from below) does not seem to be doing anything. The air is still warmer down at the bottom (like a stubborn temperature inversion). So I have switched it around to blow cold air down. Maybe that will maintain a downward air flow - we will see.  
26 Mar 2013 [01:00:00]What happened here? Amplitude dropped and going fell - suggests the pendulum got longer.  
25 Mar 2013 [19:18:20]ADJUST: +1000 ms/day to 35400 after the restart and knocking the pendulum about  
25 Mar 2013 [19:15:10]With the help of Chris Nickolaus (who did the winding) we installed a fan to even out the temperature in the pendulum chute. Thanks to Mark Rainer for making up the fan (using an old vacuum cleaner tube). Air blowing upwards (sucking warm air up)Let us see if it makes a diference!  
18 Mar 2013 [22:06:33]ADJUST: +400 ms/day to 34400 - fine tuning after the activity over the weekend  
17 Mar 2013 [10:25:01]ADJUST: +3500 ms/day to 34000 which is a big change required after last night and the brutal hacking (during which the pendulum was stopped and jolted about)  
17 Mar 2013 [01:45:00]Winders and witnesses - a Troy of Helens: Helen Arney @helenarney, Helen Scales, Helen Czerski @helenczerski, and the non-Helens: Jasmin Chana, Michael Conterio @Sci_Cam, Matt Parker @standupmaths  
17 Mar 2013 [01:41:55]GLITCH Major changes tonight - opened up the pendulum chamber with a saw (!) to improve air flow. Hope it will work.  
10 Mar 2013 [14:28:21]So here is a theory: If the temperature down at the pendulum bob is high then the temperature compensation is not dealing with change in air density (buoyancy). This effect is +30ms/day per degC so a 4C warmer bottom would give rise to a +120ms/day on going. This is not far from observed - note that the clock slower down overnight as the pendulum chute cooled down. Maybe I need to open up the chute to contrive that cool air can get down to the bottom. I might do that next weekend....  
10 Mar 2013 [12:12:42]pendulum temperatures [15.0 14.3 14.3 11.1 9.9] and note that the minima overnight were [10.9 11.0 11.0 10.9 9.8] so it looks as if the pendulum bottom half cools down a lot overnight.  
09 Mar 2013 [13:00:00]ADJUST: -300 ms/day to 30500  
09 Mar 2013 [12:00:00]today installed four thermocouples to measure the temperature down the pendulum shaft. Temperatures now are [15.7 15.2 15.0 11.9 11.9] in degC from bottom to top. the last reading is in the clock chamber . Note that the bottom three readings are where the pendulum swings in the room below - it is clearly warmer there.  
04 Mar 2013 [23:03:43]Rob Dwyer-Joyce paid for his dinner by winding the clock tonight - well deserved, said the clock!  
26 Feb 2013 [23:49:41]Conductors - NOT organists! - Alexandra Schwinn, brilliant, Yasmina Sabbah, Zvika Vogel, Sam Allchurch, Stephen Layton, Curtis Kettler - and heaven forbid - did it strike thirteen?  
26 Feb 2013 [17:08:14]Jack Stilgoe did the two heaviest winds (!) thanks for the assistance  
20 Feb 2013 [14:14:55]Igor Wowk worked up a sweat today! (well, ran out of breath at least) Many thanks.  
09 Feb 2013 [16:16:14]ADJUST: +400 ms/day to 30800  
05 Feb 2013 [21:16:40]Strange glitches in going related to temperature changes, perhaps stiction in the temperature compensated pendulum? It has a zinc tube core around a steel rod and perhaps the zinc contracts in cold weather and grips the rod. I will probably have to take the pendulum apart at the time change next month.  
05 Feb 2013 [19:43:29]LIVE on Sci_Cam - Watch the show live from Trinity College Clock Tower with Michael Conterio @hughhunt now! [link]  
03 Feb 2013 [11:55:13]winding today with the help of Roger Kelly - good to have another engineer at hand!  
01 Feb 2013 [00:26:22]Great to be up with Emma. And Jim (Beam). And expert winders Jess Nyahoe (who was impressed by my clock), Tony Hoskins (less impressed), Ben Watkins. Pat Willis (roof far too cold), Graham Jones (glass always fuller than expected)  
25 Jan 2013 [23:14:13]Wonderful winders, with the help of Jim Beam, are Andrew Pontzen, Helen Keen, Andrew Holding and Timandra Harkness.  
25 Jan 2013 [23:03:20]ADJUST: +1000 ms/day to 30400 - it seems the weather has got warm again! Woo  
24 Jan 2013 [22:10:00]not sure what the collective noun for a bunch of haematologists is, but they were excellent winders tonight!  
19 Jan 2013 [18:03:52]ADJUST: -1000 ms/day to 29400 Graham Steed helped me wind (not bad after several jars at the Cambridge winter beer fest), and adjust - it seems that this cold weather has accelerated the clock rather...  
18 Jan 2013 [00:00:00]a bunch of winders, all engineers - after their conference. A pity Emma Watson was not there. Bogies.  
13 Jan 2013 [12:40:00]winders David Thorp and Amanda Thorp with help from their sons William Thorp and Oliver Thorp - many thanks!  
10 Jan 2013 [11:12:09]great Aussie winders: alice tilson, charlotte fels, eleanor fels, Harriet Fels, Maddie Fels, Stephanie Loyola Fels, Michael Ignatious Fels of Flemington, Rebecca Fels, Emma Fels, Nick Fels, Robert Fels, Boyd Hilton  
07 Jan 2013 [00:59:22]winders tonight ... Matthew Turner, Ivan Hare, Kate Mason, Will Pullen assisted by Caroline Fletcher, Isaac Zailer, Sophie Hare, Dmitri Levitin  
13 Dec 2012 [13:55:00]Just like the Camberwick Green musical box the clock was exquisitly wound by Pam Daish and Lynn Clift. No sign of bogies this time... But we did correct by -15 seconds for the apparent pigeon-on-the-hands events this morning and yesterday.  
13 Dec 2012 [07:45:00]another pigeon?  
12 Dec 2012 [09:15:00]was this a reverse pigeon event? The clock was 10 seconds slow later in the dat...  
06 Dec 2012 [13:18:10]Winders today, Dominic Wood, Richard McCourt, Miles Harris and Patrcik McKeeman - all jolly good fun (and a lot of bogies)  
02 Dec 2012 [14:00:00]Thanks also to winders David Molony and Claire Jackson  
29 Nov 2012 [08:57:30]Restart after clock stopped (forgot to wind it!) Thanks for winding help from Sophia Sosnina and Christina Gladkova (very energetic 4-handed!)  
28 Nov 2012 [08:30:00]Thanks to Takashi Tomura, Chris Warrington and Karen Wells (Trinity Garden staff) for organizing the cherry picker to go up to see the anti-pigeon wire on the minute hand. All seems OK, though the wire was a bit bent - clearly there have been visitors. Thanks to the gardeners for clearing out the pigeon shit from behind the dial, and finding at least one egg!  
21 Nov 2012 [13:11:38]ADJUST: +150 ms/day to 30400 - Thanks to Graham Newman for his annual grease and oil change. And also for doing the clock maintenance.  
19 Nov 2012 [20:05:24]Great to have 12th Cambridge Cubs watching the winding, and thanks to Jeebie and King Louis for help with the same.  
14 Nov 2012 [12:09:30]help with winding today from David Vasak, thanks!  
12 Nov 2012 [08:35:00]4-minute correction of pigeon event. Inspection of the clock dial revealed no damage to the pigeon wire, so i) was it a pigeon? ii) if so then how did it manage to avoid the wire? iii) might it have been some other form of vermin????  
11 Nov 2012 [23:45:00]A midnight-pigeon event? - clock stopped for 4 minutes when the minute hand was horizontal. Perhaps a rat? Will need to check the anti-pigeon wire.  
10 Nov 2012 [11:00:00]ADJUST: -250 ms/day to 30250. Thanks to Ramses Verachtert for help with winding  
03 Nov 2012 [17:00:00]winding thanks to Athena Tan and Hilary Costello, who noted the new Sugru winding marks (not blue tack!)  
28 Oct 2012 [09:00:00]ADJUST: -2400 ms/day to 30500, adjustment required after refit of barometric compensator  
28 Oct 2012 [00:15:00]restart - after fiddling around with the barometric compensator, installing two new aneroids. We will see if there is a difference....  
27 Oct 2012 [23:05:00]GLITCH clock stopped for end of Summer Time, witnessed by Krisztina Szilagy, Michael Koehl, Heonik Kwon, Florence Privett and Rick Lupton who is helping with the data acquisition system and Mark Rainer who is helping with the barometric compensator and UPS  
09 Oct 2012 [11:00:00]Thanks to Roderick Blevins for help with winding  
01 Oct 2012 [20:00:00]rather a large (drunken? no, surely not!) bunch of freshers came up to see the clock. The glitch is presumably due to air density change affecting the pendulum buoyancy. Could this be? What is the partial pressure of ethanol in air?  
28 Sep 2012 [11:35:40]There must have been a power failure because the PC was not running when I came in just now. Restart successful. Must fix the uninterruptable power supply.  
28 Sep 2012 [11:15:00]Useful observation: the strike (both Trinity and St Johns) survived 10, 11 and 12 beyond the 7-day winding, ie 10+11+12=33 strikes. This means that the usual afternoon winding time would be satisfactory up to just before 8pm because 1+2+3+4+5+6+7=28. By this time however the going will have run out of juice.  
28 Sep 2012 [11:05:00]Thanks to visiting winders: David Sloan, Adam Caulton, Brian Pitts, Jeremy Butterfield (the last only did the light-weight job)  
21 Sep 2012 [08:35:00]Sophie Hunt, my niece from Melbourne, did a great job winding today. Muscle building!  
14 Sep 2012 [09:10:46]winding today from the bowels of the kitchens!! Chris Appleby and Malcolm Winter were excellent - saves me building up a sweat.  
31 Aug 2012 [12:02:03]Great to have winding help today from Daniel Flack, Anne Bahnweg, Lucy Oswald, Len Howlett - all very expert!  
30 Aug 2012 [14:15:00]visit to clock with Robyn Williams, presenter of The Science Show, ABC Radio National  
24 Aug 2012 [13:00:00]Excellent winding from Robin Sharp and Greg Winter  
01 Aug 2012 [13:00:00]Winders today were Rosie Spear, Alexander Wedgbury, Kateri Spear and Len Howlett - Mark Rainer just stood by and watched!  
27 Jul 2012 [18:00:00]Curious that the clock shifted to its new fast-going regime at the time of winding on Thursday. Nothing was touched, other than to open the cabinet and wind. I am increasingly convinced that changing air currents up the pendulum chute are the cause. What I need now is a means of measuring micro-air-flow.  
26 Jul 2012 [18:00:00]many thanks to winders from the Cambridge International String Academy Summer Festival Concerts 2012 - very enthusiastic!  
14 Jul 2012 [14:30:00]Thanks to Rick Enns, Gabrielle Enns, John Enns and Hilary Costello for winding so expertly.  
08 Jul 2012 [09:40:44]Great to have Andres Romero from Bahia Blanca and Roger McClure - who did all the hard work winding!  
01 Jul 2012 [15:12:06]Nandi Chinner and Elkie Wootton (niece and honorary niece of Graham Chiiner) - all three came up for a visit and a wind. Thank you!  
01 Jul 2012 [13:10:00]visitors to the clock: Iona Goddard, Barney Goddard, Joel Tutt, Finlay Low, Luise Grosche, Moshe Peck, Jacob Peck, Armin Grosche, Rachel Peck, Emma Widdis, Jason Goddard, Hamish Low, Scarlet Schwiderski-Grosche, Malte Grosche, Sanam Moshar, Joel Peck  
01 Jul 2012 [13:06:40]more power failure problems, computer restarted.  
01 Jul 2012 [00:00:00]Dammit! A leap second. I do not think my pendulum cares a gnats tock about this!  
30 Jun 2012 [09:42:20]great to have visitors Katherine Gray, Lesley Gray, George Knight, Ivy Knight - top-up wind, so I do not have to do it until next weekend! We did a little experiment, removing 1200ms/day for a few minutes. That is what happens when you are having fun!  
29 Jun 2012 [13:38:22]computer restart after power failure yesterday.  
28 Jun 2012 [13:43:20]power failure caused computer to stop logging. Of course the 102-year-old clock was unaffected!  
19 May 2012 [07:15:00]restart - thanks Anson!  
19 May 2012 [03:00:00]Dammit, I forgot to wind the clock! Full marks to Anson Cheung for spotting this...  
05 May 2012 [12:07:00]Thanks to winders Viv Williams (who did the heavy one) Cathy Aynsley, Miki Booth, Adam Booth and Mark Rainer  
02 May 2012 [17:00:00]ADJUST: +200ms/day to 32900 thanks to Mark Rainer for this, and for winding  
26 Apr 2012 [23:00:00]ADJUST: +200ms/day to 32700  
24 Apr 2012 [16:00:00]ADJUST: -500ms/day to 32500 Thanks to Ted Popper and Annie Kingsbury (Popper) for help with a top-up wind.  
22 Apr 2012 [11:30:00]Anyone noticing a glitch here - well, I was demonstrating the effect of adding a 1s/day weight.  
22 Apr 2012 [11:00:00]Rather a large delegation today - Jeremy Fairbank and his co-lunchers, plus Philip Hardie and his guests. Clock now wound. We seem to be on a Sunday routine. Back to Tuesdays this week, I think.  
20 Apr 2012 [16:00:00]Great to have Joe and Betty Davidson visiting - and topping up the heavy quarters weight - less to do next time!  
19 Apr 2012 [15:30:00]The system is up and running again - not exactly in the best way. We have resurrected the old PC and will now try to repair the new one. At least data is streaming again now. many thanks to Rick Lupton for his help today.  
15 Apr 2012 [12:00:00]ADJUST: -100ms/day to 33000, winding with help from Simon Wallfisch, Sandy Hunt and Jonathan Hunt  
12 Apr 2012 [10:28:41]Guys, would you like to come into the IT Department for a chat. We are not an experts in this field, but we might be able to help (we have friends). We are in Bishops Hostel staircase D.  
08 Apr 2012 [19:59:54]Apologies that the data logging system is still down. Anson and Tim have a solution in hand - it just requires the right few hours to do it. Many thanks, you two. Meanwhile the clock is still fine - it is about 1.2 seconds fast.  
01 Apr 2012 [16:07:25]ADJUST: -100ms/day to 33100 and very kindly helped with winding by Juliet Babinsky, Carolyn Babinsky, Holger Babinsky, Giovanni Pellegrini and Ruth Pellegrini all of whom are stronger than they thought!  
01 Apr 2012 [06:30:58]So where are we: Tim has now also spent a lot of time on this. He says: The short story is that the National Instruments drivers are not working with the new kernel version after the upgrade. The longer story: the drivers check the kernel version by looking at its second digit. With the recent change in numbering, from 2.6.whatever to 3.n1.n2 (without actually a massive leap in the code) this is not particularly helpful. Anecdotal reports on the internet suggested the drivers should still work if these checks were removed. After a bit of work to disable them in the installation scripts, it almost installed. A change to the way locking is handled (linked to removal of the [Big Kernel Lock ], so I understand!) meant that a small change to the ioctl code was needed (which I did not really understand; it looked like an old callback is no longer allowed, and needed removing). Finally, everything compiled and the nikal kernel module loaded (with a memory allocation error in dmesg, but at least it appears to lsmod). Unfortunately, clocklogger then returns [ failed to initialize - Perhaps you need to run updateNIDrivers - Aborted ] So it looks like NI need to update their drivers. In the meantime, I am running out of ideas short of using an old kernel again (which would be annoying!).  
01 Apr 2012 [06:30:57]Anson has checked the disks - here is what he says: there were so corrupted inodes that come up as part of the e2fsck run in the root partition. The home directories seemed fine. There is no way of recovering easily the problems because I cannot see how the inodes correspond to actual files. So, I am going to upgrade the operating system tonight to either 11.4 or 12.1. This is a wise thing to do anyway given what we were using before 11.3 is out of support - and the original lost files harder to find.  
25 Mar 2012 [14:18:59]Ah. Apparently there was a huge power surge on 20 March at 01h30 - the same time as the PC crash. There is clearly some work to do here....  
25 Mar 2012 [13:45:00]Sorry, I have been away from Cambridge and have not had time to fix the problem. I think it is a NiDAQ driver problem because the output file says [DAQ Error]. Not very helpful! Tim, any ideas?  
25 Mar 2012 [13:00:00]winding help from Anna Gatti, Nico Gatti, Sofia Gatti, Alessandra Tosi, Rupert Gatti, Valentina Corsetti, Christopher Peacock and Dilan Mehmet - a really very helpful team!  
25 Mar 2012 [07:05:00]GLITCH Clock advanced for summer time  
20 Mar 2012 [17:00:00]ADJUST: -100ms/day to 33200 - maybe it has a mind of its own!  
20 Mar 2012 [01:30:00]Computer crash - under investigation  
13 Mar 2012 [14:00:00]ADJUST: +100ms/day to 33300 - thanks Mark.  
09 Mar 2012 [18:15:00]ADJUST: +2000ms/day to 33200 Tim very helpfully went back to regulate - by a huge 2s/day. Hmm, what has changed?  
08 Mar 2012 [20:45:00]GLITCH Tim gale very helpfully went to find out what was happening - found things in a bit of a mess, the cable had been pulled out of the weather station and had to be refitted. This meant stopping the pendulum (the weather station is down the pendulum chamber). Restart, hopefully it will settle down quickly. Teally not sure what caused all this - I suspect the Works Department had to move the computer to gain access to a cupboard, and I think they pulled out the USB cables, then put them back in again..  
07 Mar 2012 [11:15:00]Something happened here.  
03 Mar 2012 [15:00:00]ADJUST: +100ms/day to 31200  
28 Feb 2012 [12:16:40]ADJUST: -200ms/day to 31100 because I want to have the clock back at 0 for the clock change in March  
28 Feb 2012 [12:15:00]Great to have help from Sally Pettipher who is on a fitness drive for her coxing.  
21 Feb 2012 [22:10:00]Rosemary Richards and Jeremy James from Grantham GravityFields Festival helped with winding today - they now know what gravity is!  
21 Feb 2012 [21:50:00]poor PC has not had a rest since Occober 2011, needed a restart.  
07 Feb 2012 [15:09:14]A whole heap of helpers today ... Harry Clift, Eloise Hunt, Lynn Clift, Janet Procter - all very muscley!  
31 Jan 2012 [13:17:33]Jonas Coene helped with winding - thanks!  
24 Jan 2012 [13:13:50]Many thanks to Simon Raikes for throwing his weight around today!  
17 Jan 2012 [12:06:07]Winding helpers today: Madelaine Crush, Janice Chambers and Rob Hogan - many thanks!  
10 Jan 2012 [19:00:00]Not sure what caused this gap in data. The PC seems to be fine because weather data has been collected. Perhaps the GPS receiver was doing a software upgrade?  
10 Jan 2012 [16:58:46]Thanks Janar Davletov (from the Bursary) for help with winding!  
04 Jan 2012 [04:31:40]Barometric compensator: Why does the compensator appear to be working for rapid changes in pressure (ie over a few hours) eg [link] [link] but not for slow changes in pressure (over a few days) eg [link] [link] A real mystery. Perhaps there is a link between pressure and temperature, or maybe updraughts?  
03 Jan 2012 [17:25:00]Thanks to Alexander Hunt for helping with a wind - just in time!  
27 Dec 2011 [13:00:00]Winding excellently assisted by Giovanni Pellegrini, Isabella Pellegrini, Luca Pellegrini and Eloise Hunt  
29 Nov 2011 [18:00:00]ADJUST: +50ms/day to 31300 and a wind, thanks to John Fisher Burns, Andrew Testa and Benjamin Barrett for saving my efforts.  
13 Nov 2011 [15:30:00]top up winding - thanks to Bianca Sporea and Devon Griffiths for trying their arms!  
30 Oct 2011 [00:30:00]... thanks to Anson Cheung and friends Michael Koehl, Jean Ho, Charles Roddie, Claire Sladden, Nicholas Teh, Olivia Skilbeck, Kate Pfeffer, Marco Selvi, Susan Raich, Matthew Willetts and Lydia Reeves for staying up so late... must have been a chore!  
29 Oct 2011 [23:30:00]GLITCH clock change for end of Summer Time.  
25 Oct 2011 [13:15:00]ADJUST: +100ms/day to 31250, thanks to Anson Cheung for company, and for agreeing to effect the clock change this coming weekend.  
10 Oct 2011 [21:30:00]ADJUST: -150ms/day to 31150, observed by Hermann Hauser and Peter Davidson - both of whom seem to understand at least a little physics.  
01 Oct 2011 [14:30:00]I put a sunshield in the left part of the window so the pendulum is in full shade at all times - note the dip is no longer occurring,  
30 Sep 2011 [14:30:00]These dips in going are due to the sun shining on the top quarter of the pendulum. The outer steel expands rapidly, the inner zinc stays cool and does not compensate. Once the sun passes then the going returns to normal.  
29 Sep 2011 [14:30:00]see above, Re: dips  
28 Sep 2011 [14:30:00]see above, Re: dips  
27 Sep 2011 [14:30:00]see above, Re: dips  
25 Sep 2011 [16:45:00]ADJUST: +150ms/day to 31300, thanks to Christine Costello and Hugh Costello who managed not to drop any weights down the shaft.  
18 Sep 2011 [13:30:00]ADJUST: +150ms/day to 31150, thanks to Howard Tuck for his company, and to help with a bit of winding.  
26 Aug 2011 [14:10:00]ADJUST: +150ms/day to 31000, thanks Mark Rainer. Perhaps the right setting is somewhere in the middle...  
11 Aug 2011 [08:00:00]ADJUST: -150ms/day to 30850 - Hilary undoing her what she did 2 weeks ago. I think this is about the right setting, on average.  
03 Aug 2011 [18:30:00]a HUGE downpour occurred at about this time - the sky was like the sea. The GPS receiver (which already can only see half the sky from its view out the window) lost sight of satellites for a few minutes, hence our temporary loss of data.  
02 Aug 2011 [13:00:00]thanks to David Hughes for help with winding...  
30 Jul 2011 [17:00:00]The webcam is now working again, and it even has sound! Thanks very much to Tim Gale.  
26 Jul 2011 [13:30:00]ADJUST: +150ms/day to 31000 - thanks Hilary.  
20 Jul 2011 [12:00:00]GLITCH Today we installed a new PC - hopefully now capable of running the webcam properly (watch this space). It runs OpenSUSE (Linux) so many thanks in particular to Tim Gale for getting the installation all working, in particular the NI-DAQ card and drivers. Impressive that we only dropped a few minutes of data. Well done Tim! Thanks also to Anson Cheung for all his support and advice. We still need to get the cron job running for automatic upload to the website. In the meantime uploads will be manual and a bit sporadic.  
19 Jul 2011 [14:57:00]Many thanks to Sian Gardner for volunteering for a workout!  
12 Jul 2011 [12:00:00]Many thanks to Lucy Leckey, Richard Leckey, Peter Dennis and Sue Dennis for winding!  
10 Jul 2011 [13:50:00]Corrected clock that was 6 seconds fast - as displayed by the hands, ie hands ahead of the mechanism - no obvious explanation. Pigeons at quarter past now? I hope not! Great to see David Greagg - now he knows the difference between a clock and a chronophage pretending to be a clock ...  
28 Jun 2011 [21:50:00]bumped the pendulum while removing the plastic pipe from the pendulum chute (installed 19 Jan 2011) - not sure it is doing anything, and it looks ugly...  
26 Jun 2011 [13:00:00]ADJUST: +50 ms/day to 30850 (thanks Ellie)  
14 Jun 2011 [18:50:00]ADJUST: +200ms/day to 30800 and wound with help from Alek Haigh, Maya Haigh, Ellie Hunt, Anna Harrison, James Dixon, Esra Haigh, Stuart Haigh  
09 Jun 2011 [11:10:00]experiment with removing then adding 5000ms/day (to show Simon and Henrietta!)  
02 Jun 2011 [11:24:00]ADJUST: -150ms/day to 30600 - with the help of James Grime who is filming all of this for his youtube channel  
24 May 2011 [17:00:00]ADJUST: -150ms/day to 30750, and help with winding from Andreas Michaelides and Srikanth Madabhushi  
18 May 2011 [20:50:00]SPICE visit: Chris Burgoyne, Hilary Costello, Tony Cox, Peter Davidson, Simon Driscoll, Pru Foster, Don Grainger, Jim Haywood, Hugh Hunt, James McGregor, Thao Do, Daniel Peters, Francis Pope, Chris Walton, Peter Braesicke, Alessio Bozzo, Matt Watson, Andy Elson, Emily Knott, Markus Kalberer - a good (and challenging) day had by all!  
13 May 2011 [15:03:00]small disturbance due to replacing the 2000+1000+1000+500+500 ms weights with a single 5000ms/day weight - witnessed by Geoff and Wendy Newton from Perth WA, and their daughter Kirsty Kuo. Not wanting to miss an opportuinity, I got them to do some winding!  
08 May 2011 [16:30:00]Visit by the AHS American Chapter, thanks to Hilary Costello for hosting. Note the glitch - visitors always cause disturbance, even horologists!  
01 May 2011 [18:15:00]ADJUST: -250ms/day to 30900 (dropped 200ms/day down the pendulum chute ... bound to happen one day)  
30 Apr 2011 [18:15:00]Barometric compensator seems to have worked pretty well recently [link] [link] as has the temperature compensation [link] [link] . There is a lot noise on these plots, pretty sure this is due to temperature gradients in the clock chamber because it seems to be worse when the sun is shining strongly through the windows and when the central heating is at its hottest in the room below.  
19 Apr 2011 [11:15:00]ADJUST: +100ms/day to 31150, thanks again Hilary. I have a far-fetched idea that going is proportional to long-term rate-of-change of temperature at -200ms/day per degC/day. This minor adjustment should help test it.  
16 Apr 2011 [13:00:00]Computer restarted after power cut, thanks again to Anson Cheung  
16 Apr 2011 [07:00:00]GLITCH Power cut, safe shut down thanks to Anson Cheung  
12 Apr 2011 [19:30:00]ADJUST: +300ms/day to 31050, thanks to Hilary Costello. I am viewing all this from a distance (Australia) and continue to be mystified at the cause of the change in drift that occurred around 5 April - is it due to rate of warming? Spring seems to have sprung around then.  
07 Apr 2011 [07:45:00]Power cut - thanks to Anson Cheung and Tim Gale for seeing to the restart.  
26 Mar 2011 [22:30:00]GLITCH Advanced clock for summer time (effected by Mark Rainer and Graham {clocky} Newman). The 30ms shift in drift is due to the removal of the mass of the gravity arms from the pendulum - same effect as removing mass from the regulation tray causes the clock to run slower. For about 3 minutes it ran about 4s/day slow. Note also the 1.2mrad drop in pendulum amplitude and the recovery afterwards.  
25 Mar 2011 [13:50:00]ADJUST: -150ms/day to 30750, may be better. Witnessed by Rebecca Loving on the eve of her departure to Chicago.  
21 Mar 2011 [06:40:00]ADJUST: +400 ms/day to 30900, back to where it was on 29 Jan.  
11 Mar 2011 [05:46:00]GLITCH Power outage (planned) complete coincdence that this is the exact time at which the Japan earthquake struck. It would have been interesting to see if the effect could be seen on the going/amplitude of the clock.  
06 Mar 2011 [11:01:00]So what effect is the sunshine having? The top 10% of the pendulum does not have zinc compensation in it so if it were sun-on-the-pendulum effect then sun should mean a lengthening of the pendulum and so the clock slowing down. But completely the opposite happens - the clock suddenly speeds up. It is the reverse of what we have seen ober the winter caused by central heating in the room below. There must be something to do with the clock chamber (which is enclosed) now being warmer than the room below, causing a reversal of the temperature gradient over the length of the pendulum.  
06 Mar 2011 [11:00:00]These kinks seem to be related to sunshine. Going was steadily downwards throughout a period of cloudy days, with occasional upward bursts wne the sun comes out. Now that other things seem to be under control (ok, now asking for trouble) the effect of sun is more obvious. There is a large window (south facing) that makes up some 30% of the surface area of the south side of the clock case, and in the afternoon the sun shines on the clock mechanism (including the top 10% of the pendulum rod --- see next comment). The window has secondary double glazing with UV film.  
26 Feb 2011 [20:00:00]nothing to report - just enjoying 2 weeks during which the clock has lost only 0.5 seconds. Not sure why the recent slowing down - temperature compensation is ok [link] , still not certain about the barocompensator [link] but there is a lot of noise on the plot. The biggest effect at the moment is draughts, I think, caused by differential temperature with the centrally-heated room below. As spring settles in we should see less of this.  
08 Feb 2011 [21:23:00]ADJUST: -250 ms/day to 30500. Reinstated the amplitude measurement plank at the top of the pendulum chamber. This might moderate the extremes of air flow that could be responsible for the observed fluctuations of going.  
01 Feb 2011 [10:00:00]clock restarted. Advanced by 4h15m - the longest pigeon event on record.  
01 Feb 2011 [09:00:00]With the help of a cherry picker I overcame my fear of heights and fitted a thin wire to the minute hand. This should, with any luck, prevent pigeons from settling on the hand. We will see.  
01 Feb 2011 [05:45:00]pigeons. This time they sat on the minute hand for such a length of time that they stopped the clock completely.  
31 Jan 2011 [14:45:00]pigeon correction +18 seconds  
31 Jan 2011 [07:45:00]yet another pigeon. I said I was serious. Now even more serious. Pigeons, beware.  
30 Jan 2011 [16:58:00]pigeon event correction, +24 seconds. Thanks to Andrew Kennedy for the company!  
30 Jan 2011 [12:45:00]another pigeon. I am seriously going to do something about this now.  
29 Jan 2011 [21:50:00]ADJUST: -150 ms/day to 30750 ... fine tuning. What better thing to be doing on a Saturday night!  
29 Jan 2011 [16:50:00]ADJUST: +1100 ms/day to 30900 This change is needed because of the opening up of the pendulum chamber earlier today. Colder air is now drifting down to the base of the pendulum and this is where most of the temperature-compensating zinc is. It contracts on cooling, so lengthening the pendulum (that is how it works). So the clock has slowed down. Really by an astonishing amount. I suspect the air at the base of the pendulum chamber must have been really warm due to the central heating below, set at 22C The pendulum case sits high up in the room so it may well be up in the high 20s C. The temperature up in the clock room is around 6C today. Let us see how it settles down, but I think this will be a new operating regime. I wonder if the amplitude will do anything different now that air currents will be altered?  
29 Jan 2011 [13:05:00]For the record, since I moved the weather station here are links to glitches that show the differential temperature effect have been happening often: [link] [link] [link] [link] [link] [link] [link] [link] . They all 1296306299 +0 point to a differential temperature effect of about 150 to 200 ms/day /C thus supporting the hypothesis presented here.  
29 Jan 2011 [13:00:00]Having inserted the tube and opening up the chamber I am hoping we will see more uniform (and perhaps lower) temperatures down in the pendulum chamber and as a result I hope to see better temperature compensation.  
29 Jan 2011 [12:35:00]Unfortunately I bumped the pendulum a few times while installing the tube - hence a few glitches.  
29 Jan 2011 [12:30:00]I removed the boards at the top of the pendulum chamber and inserted a 1metre long 40mm tube down into the pendulum chamber with a view to encouraging cool air to descened, mix with and displace the warm air below (see photos [link] [link] thanks to Wu Hao). It has become clear that the cause of the apparent unsatisfactory temperature compensation is the fact that the lower half of the pendulum is about 2C warmer than the top half and this only occurs on very cold days. Here is an example [link] where changing tempurature of the lower half of the pendulum results in a change in going.  
29 Jan 2011 [12:28:20]Here is my thinking on the errors of temperature compensation. On a cold day the clock case is about 1.5C colder than the pendulum chamber as was observed on the day I moved the weather station: [link] The ideally compensated pendulum has a zinc element 2/3 the length of the pendulum (for coeff expansion Zn/Fe = 30/12 ). The bottom of the zinc element is at the bob CoM (near enough) so the top 1/3 of the pendulum length is steel with no zinc.. A temperature differential T between top and bottom (colder at the top) gives a going change of + 0.5 * 1/3 * 12e-6 = + 172ms/day /C so the 1.5C observed difference will cause the clock to run 260ms/day faster. Recent data shows that the going in the recent cold weather is about 300ms/day faster than it was in milder times [link]  
29 Jan 2011 [12:28:19]which is closely consistent with the calculation of 260 ms/day for the observed 1.5C temperature difference.  
19 Jan 2011 [11:27:00]GLITCH power outage, this stopped the logging PC even though we have a UPS... Restarted at 12h45. I took the opportunity to install some proper weights for the fly (in brass 10.5 grams each, thanks to Mark Rainer for making these) so that it spins slower and impacts less on the escapement legs. This will help avoid reverse pigeon events. The amplitude dropped during the 4 minutes it took to install these.  
17 Jan 2011 [08:50:00]pigeon correction, +1m21s. I am often asked - surely the virtue of the gravity escapement is that it is immune to disturbances on the hands like wind, snow, birds - yes, but there is a limit. If the pigeon provides a reverse torque greater than the forward torque provided by the drive weight then the clock will stop. It is like the cruise control in a car, if there is a head wind or if you go up a hill then the control works fine but if the wind is too strong or if the hill is too steep and it overpowers the engine then the car will slow down. I have done this calculation [link] and it turns out that perhaps one, probably two pigeons sitting on the minute hand at quarter to the hour will stop the clock. Of course, sitting on the hand at quarter past the hour adds power and up to a point the escapement can cope. I suspect that the escapement has jumped on at least one occasion  
17 Jan 2011 [08:49:59][link] perhaps due to a pigeon?  
16 Jan 2011 [14:45:00]yet another pigeon event [link] , looks to be over a minute - perhaps two. You can see that the pigeon(s) went away and came back. I need a photograph - the only one I have is of a pigeon on the hour hand.  
16 Jan 2011 [01:01:00]pigeon event correction, it was 21 seconds. Thanks to Beatrice, Madonna and Indiana Jones!  
15 Jan 2011 [08:42:00]Looks like another pigeon, my guess is 42 seconds looking at [link] because there is a point plotted every 3 seconds  
13 Jan 2011 [20:00:00]correction of pigeon event, +57 seconds, witnessed by Evelina, Dop, Ben, Simon, Tony, Chris and Graham - on a jolly from the Netherlands!  
13 Jan 2011 [17:45:00]Pigeon event - pigeon stopped clock for 57 seconds, the bastard. [link]  
11 Jan 2011 [10:00:00]What caused this amplitude shift? There is a small drop in temperature and if you look at amplitude v. temperature over the last month (since the weather station was moved into the pendulum chamber) [link] you see multiple episodes of correlation between amplitude and temperature, but these are probably due to changes in drag (temperature rise causes density drop). My theory though is that a temperature rise also indicates a change in air flow so that warm air is now rising causing amplitude increase. Maybe a good idea to seal up the pendulum chamber more properly.  
10 Jan 2011 [06:35:00]ADJUST: +300 ms/day to 29800 - curious that ths is 3000 heavier than it was before the barocompensator was removed. Mysterious. Surely the same device returned to the same location should need the same compensation mass.  
08 Jan 2011 [11:40:00]ADJUST: -3400 ms/day to 29500 to compensate for the mass of the barocompensator  
08 Jan 2011 [11:02:00]Barometric compensator reinstalled, in the same place it was (up near the pivot) because I want to give it another chance. Thanks to Hilary for clambering around behind the clock, all witnessed by The Strassers (Mike, Lou, Peter, Andrew) and Jonnie Hunt.  
06 Jan 2011 [14:00:00]Mark has measured the expansion coefficients for both the aneroids at 0.03 mm/mbar - so they are working fine. In fact this is 40% more sensitive than I had assumed, so it is a mystery why the barocomp is not working. I have a theory that there is something funny about the way the flexure of the pendulum suspension works, so I am going to have a go putting the compensator further down the pendulum, away from the flexure. This is what Philip Woodward did ... so maybe there is a good reason. It will mean having to screw up the regulation nut under the bob again - which is what stuffed up the temperature compensator last time. Ah well, it all makes work for the working man to do.  
06 Jan 2011 [10:00:00]... the observant amongst you will have noticed that the clock sped up by 3 seconds retrospectively. This is not relativity in action - it is simply that the clock is actually sounding half a second fast at the moment, so I have brought the logger in line with the real world. Yes, there is a real world!  
05 Jan 2011 [21:30:00]So the barocompensator is removed. This means that I now have to do what I used to do and check the pressure forecast at BBC weather [link] because I know that the clock loses -8ms/day per mbar of pressure rise. The barometric presssure is due to rise by 20mbar over the next 6 days so lets see if the clock slows down by 120ms/day.  
05 Jan 2011 [19:00:00]ADJUST: +5500 ms/day to 32900 now that the barocompensator has been removed  
05 Jan 2011 [18:55:00]The old computer as been reinstated until we can figure out compatibility of NiDAQ drivers with OPENSUSE 11.3 Many thanks to Tim Gale for his help! Useful to record that NiDAQ drivers are updated using sudo updateNIDRIVERS `uname -r` and also to update to the server use lftp -f uploadData.lftp .  
04 Jan 2011 [14:35:00]Removed the barometric compensator for bench testing - this required stopping the pendulum. Thanks to Hilary Costello for climbing around behind the clock.  
04 Jan 2011 [12:00:00] Datalogging suspended due to replacement of computer - the old one did not have enough memory to run the webcam reliably. Thanks to Tim Gale and Anson Cheung for all their efforts  
02 Jan 2011 [13:20:00]ADJUST: +400 ms/day to 27400 thanks to Mark Rainer. The barocompensator is not doing its job. I will remove it on Tuesday and give it a good look over.  
31 Dec 2010 [11:30:00]It is hard to tell how well the barometric and temperature compensators are working because temperature and pressure change at the same time. This is where the monitor page come in [link] because an equation for working out drift from temperature and pressure data can be tested. The equation I am testing is: Going = -120*(Temp-6)-8*(Pressure-1013)-40*dTemp/dt -60) and it fits pretty well. Here is a direct link to the drift estimate and the actual drift - a good fit [link] and the XY plot [link] shows a straight line. If this equation is right then it means that the variation of going with temperature is -120 ms/day per deg C [-520] , with pressure is -8 ms/day per mbar [-8] and with rate-or-change of temperature is 40 ms/day  
31 Dec 2010 [11:29:59]per degC/day [0]. The values in [ ] are for an uncompensated pendulum.  
23 Dec 2010 [13:55:00]ADJUST: +100 ms/day to 27000 thanks to Hilary Costello and Alice Cicirello  
21 Dec 2010 [12:30:00]ADJUST: -500 ms/day to 26900  
19 Dec 2010 [09:38:00]Bedmaker Effect, interim conclusion: 1: opening the door in the room below on a cold day causes the air flow in the pendulum chute to change (a cold downwards air flow is replaced by a warm upwards air flow) because of the chimney effect forced by the tall heated staircase in the building. 2: as the air warms up, the density and viscosity of the air both fall allowing the swing amplitude to increase. 3: The change in direction of air flow (downward to upward) causes the Going to drop (the clock slows down) because upward drag on the pendulum causes an apparent reduction in g.  
19 Dec 2010 [09:37:00]Bedmaker Effect (continued) 2: the Going changes more dramatically [link] . What is interesting is that there is a step change in going of about -900ms/day and this occurs straight away, not at all related to the gradual temperature rise. This is clear in the scatter plot [link] (ok, there is a gradient at the expected slope due to thermal expansion, but this is after te initial step occurs. It was Dwight Elvey who made me look again at this, and I think he is right - the observed change in going could well be due to the change in air flow up the chute. If descending cold air is replaced by rising warmer air then the sudden change in direction of air flow will cause a change in Going. This has been looked at in the Theory section of the website, and in Section 4.6.4 and  
19 Dec 2010 [09:36:59]estimate was calculated as -300ms/day per 1m/s of upward air flow. This suggests that the change in upward air flow this morning should have been around 3m/s - which is pretty fast. Certainly measurable. I will have to invest in a digital anemometer now!  
19 Dec 2010 [09:36:00]Bedmaker Effect (continued) So, here are some observations: 1: amplitude changes linearly with temperature, as can be seen in a scatter plot [link] and the fact that the rise curve and the fall curve follow each other (ie there is no hysteresis) really suggests that the temperature sensor responds quickly to temperature change and that the amplitude measurement is due to air temperature change. The gradient is about 0.8mrad/C which agrees really well with theory for how drag varies with air density. Nothing definite yet, but the evidence for this theory is mounting.  
19 Dec 2010 [09:35:00]Bedmaker Effect, just opening the door (no bedmaker!) on a cold morning, -4C outside. Heating on inside, really toasty. So, opening the door causes a chimney effect, forcing warm air into the pendulum chute. This temperature rise can now be seen [link] because the weather station is located in the pendulum chute itself. I have made some observations and these are in separate comments above.  
18 Dec 2010 [12:01:00]Conclusion on temperature sensitivity of sensor: It seems that the sensor setup is not temperature sensitive over the range of temperature changes observed in the Bedmaker Effect (below 1C change). The key indicator is seen here [link] where the amplitude change when a hairdrier is blown onto the sensor is in the wrong direction.  
18 Dec 2010 [12:00:00]It is good to see that the clock has settled down to where it was. [link]  
18 Dec 2010 [09:39:27]Expt 3: [link] Now a hair drier is used to warm up the sensor, and at the same time part of the pendulum shaft is warmed up (it is not possible with a hair drier to target the sensor being so close to the pednulum shaft). We see that there is a small change in indicated amplitude, and this is downwards consistent with the negative temperature sensitivity of the sensor as found in expt 1. But most significant is a very large change in going (slope of the drift) to -1700ms/day. This is consistent with lengthening of the pendulum due to thermal expansion, and it is a large effect because the hair drier is quite hot.  
18 Dec 2010 [09:33:36]Here [link] I bumped the pendulum while moving the temperature sensor into the pendulum chamber. The idea now is that the temperature indicated on the website is now the temperature inside the pendulum chamber rather than in the clock case.  
18 Dec 2010 [09:21:33]Expt 2: [link] The same again, but the soldering iron is in place for about 5 minutes. This time there is a bigger effect on amplitude (about -0.2mrad) but again no significant effect on going. The thing to note is that the indicated amplitude change is negative, so that the effect of rising temperature is to reduce the indicated amplitude, but temperature change does not appreciably change the indicated rate of Going. The air temperature that the soldering iron produces around the sensor is HOT - very much higher than anything that the central heating will produce. It seems then that while the sensor is indeed temperature sensitive it cannot explain the Bedmaker Effect.  
18 Dec 2010 [09:17:30]Experiments, in the light of helpful comments by Dwight Elvey who rightly points out that the optic sensor is probably temperature senitive. See [link] . Expt 1: placed a hot soldering iron under the sensor for about 30 seconds (wanting to warm up the sensor without warming up anything else). Note that the amplitude drops by about 0.05mrad while the going (slope of the drift) is unchanged.  
17 Dec 2010 [09:05:00]It is good to see a prediction come true! Interesting to note, with a longer period of the door being open, that the amplitude looks to be increasing exponentially by about 0.4mrad at a time constant of about 20 minutes. The going does not show any decay - just a step of about -450ms/day. This reinforces the theory that the change in going is due to a change in length of the outer tube due to thermal expansion - corresponds to a temperature change of +1C. The puzzle to figure out now is a mechanism for the observed change in amplitude that corresponds to a change of +1C.  
17 Dec 2010 [07:40:00]I asked the bedmaker to leave the door open for 20 minutes today [link] . Another concern: is the barometric compensator working [link] ? The blue data points should form a horizontal line - but they are following the -8ms/day per mbar lines exactly as we had before the compensator was installed.  
15 Dec 2010 [14:50:00]ADJUST: +200 ms/day to 27400 - not getting this nailed as quickly as I would like. Hopefully then clock will drift toward zero over the next few days and then I will make a final adjustment in the new year.  
11 Dec 2010 [07:40:00]The Bedmaker Effect is absent - as expected, it is a Saturday. But I have a theory for what has been going on, and the sums sort-of stack up [link] . Essentially, warm air is forced into the pendulum chamber causing amplitude to increase due to reduced drag and going to decrease because the outer tube of the pendulum warms up - it takes a while for the temperature compensation to reach equilibrium. A test to do on a cold morning next week will be to leave the door open for long enough for an equilibrium to be reached.  
10 Dec 2010 [09:30:00]ADJUST: -900 ms/day to 27200 should stabilize now that the draught-up-the-pendulum problem is fixed  
10 Dec 2010 [07:45:00]cleaning lady leaving the door open. Hopefully over the weekend there will be no such glitches at 07h45, nor next week during which I have asked her to leave the door closed. Perhaps, as a treat, I will let her open the door next Friday!  
09 Dec 2010 [07:35:00]So the plot thickens. I went in at 07h30 to see what is responsible for this amplitude glitch at 07h35 every morning [link] , it happened again today. Is it the strike silencer? No, this releases at around 07h20. Is it the sun at sunrise? No, the sun does not shine on the clock tower until about 08h10, and it is not until 08h45 that the window into the clock case is out of the shadow of the S-E turret. Is it the central heating switching on? Well, not sure, but the event is so sudden and short-lived that the heating switch-on cannot really be responsible. But at precisely 07h35 I heard a noise. It was the cleaning lady opening the door of Dr Hopkinsons room below. I went down to see her and asked if she came in at this time every day and she said yes, exactly this time - not on weekends. How long does she stay? About 10 minutes. Now, when she cleans she leaves the door wide open.  
09 Dec 2010 [07:34:59]This might explain why Dr Hopkinsons comings and goings have no effect. So I asked her if she would leave the door open again tomorrow but next week she will close the door when she cleans. We will see if it makes a difference. But I am still really puzzled: the pendulum chamber is now (since Tuesday) fully taped up and I cannot see any obvious places for draughts to get anywhere near the clock. Maybe there is a non-draught-related explanation - perhaps the cleaning lady is attractive to long swinging objects? Next week will be interesting. (By the way, this glitch is small by comparison to others eg pigeons and spiders, but it is curious all the same)  
08 Dec 2010 [18:22:00]here is an experiment, showing the effect on amplitude of the maintaining weight [link] , over a period of 18 minutes. It seems that the maintaining weight reduces pendulum amplitude at a rate of 0.01mrad/min. This is due to pallet friction, I think. It makes the effect observed earlier today all the more puzzling - the same rate of change but in the opposite direction! Note that the increased maintaining weight has no effect on going, but the 07h35 glitch shows on amplitude AND going. There is another effect in play here. What a mystery!  
08 Dec 2010 [07:35:00]what is this glitch [link] ? It lasts for about 10 minutes, increases amplitude by about 0.015mrad/min and seems to occur every morning at around 07h35. Now that the draught problem appears to be solved we can see more little features. maye it is something to do with the strike-sliencing mechanism? The thought is that it affects the going train as it releases between 7am and 8am. But surely this should have the same effect as the maintaining weight - ie increasing pallet friction and therefore reducing pendulum amplitude. I should check the effect of the maintaining weight this evening.  
07 Dec 2010 [23:00:00]sealed up the pendulum chamber with tape, thanks to Hilary Costello for help. Note that pendulum amplitude drops straight away - a good sign. The amplitude rapidly settles to a steady value overnight. The test will be at 8am tomorrow - will there be a glitch in amplitude? I hope not.  
07 Dec 2010 [08:00:00]Recently there have been sudden shifts in pendulum amplitude starting at around 8am every day. I suspect this is when the heating comes on, or perhaps when the cleaning lady opens the door in the room below. It is regular as clockwork on weekdays (see today(Tuesday) [link] and yesterday [link] but note that there was no glitch on Sunday [link]). Whatever the cause, recent cold weather has highlighted the variability of pendulum amplitude with air temperature. There is a cold draft coming out of the cracks around the door of the pendulum chamber so perhaps air currents around the pendulum are to blame. Suspected this for ages, so maybe tonight I should  
07 Dec 2010 [07:59:59]seal up the gaps and find out.  
05 Dec 2010 [16:30:00]ADJUST: +1100 ms/day to 28100 The amplitude is very high. Is there something to do with a cold draught in the pendulum shaft? Replaced covers to minimize space for air flow.  
02 Dec 2010 [12:00:00]Many thanks to Douglas Young for modifying the code to deal with temperatures below 10C - it was one of those coding things, that the data file had two spaces when the temperature was one digit, meaning that temperatures were not read in at all. Now we can monitor effects as the temperature plunges.  
28 Nov 2010 [15:50:00]ADJUST: +600 ms/day to 27000 still settling in  
28 Nov 2010 [13:30:00]ADJUST: +700 ms/day to 26400  
27 Nov 2010 [21:10:00]ADJUST: +000 ms/day to 25700 note that we have a new weight configuration  
27 Nov 2010 [20:30:00]Note that the temperature rose during this exercise - we had a fan heater going because the outside temperature was sub-zero. This should give us a good opportunity to see if the temperature compensation is working as it cools down overnight...  
27 Nov 2010 [20:00:00]We finally got it all back together after about 5 hours work, only to find that the clock was gaining about 140 seconds per day. We then had to wind down the regulation nut on the pendulum bob by 3.5 turns. We then had to reset the bells, but in so doing we found that the second hand was out-of-synch with the quarters bells. All these unintended consequences of our simple readjustment of the pendulum!  
27 Nov 2010 [18:00:00]We re-assembled the pendulum, but in so doing we noticed that we had bent the gravity arms of the escapement. In order to prevent further damage we removed the gravity arms. We also re-instated the original suspension (as was removed in October). The repositioning of the gravity arms caused problems with bouncing of the escapement so we decided to adjust the fly on the escapement. This did not work so we had to dismantle the fly.  
27 Nov 2010 [16:20:00]Today we (Graham Newman, Mark Rainer, Hugh Hunt) had a go at fixing the temperature compensation of the pendulum. We stopped the clock at 16h20, disconnected the barometric compensator, removed the optic sensor, then Mark had made up a neat cradle for the pendulum bob so that we could remove the pendulum shaft while leaving the bob behind. We then dismantled the pendulum. There was a bit of corrosion but not enough to explain a lock-up of the compensator. We found that the zinc tube was bent by about 3mm at its centre - perhaps enough to have locked the mechanism up if it had got twisted?  
16 Nov 2010 [21:15:00]Correction of -15 seconds for a reverse pigeeon event. It seems that the removal of the weights on the gravity arms (17h30 30 Oct) means that the gravity arms jump more easily, as observed when the maintaining weight is engaged alongside the main driving weight. A Pigeon on the hands at hh:15 will have the same effect as a maintaining weight.  
16 Nov 2010 [15:35:00]ADJUST: +800 ms/day to 29500 It is clear that the temperature compensation has gone wrong [link] . Quite possibly when we adjusted the regulation nut we managed to jam something in the set of steel/zinc concentric tubes that make up the pendulum [link]  
11 Nov 2010 [08:00:00]TC works staff were checking out clearance in the pendulum case - they must have touched the pendulum  
09 Nov 2010 [13:25:00]ADJUST: -500 ms/day to 28700 Now that the pendulum is swinging nicely we can see that the temperature compensation is not ideal - sticking somewhere?  
04 Nov 2010 [08:25:51]ADJUST: +500 ms/day to 29200 maybe the new suspension is settling in. No matter how tight the screws are the spring will ratchet down against friction.  
02 Nov 2010 [14:30:00]ADJUST: +200 ms/day to 28700 - a minor adjustment, given how much change there was on Saturday  
30 Oct 2010 [20:00:00]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 [18:30:00]the clock was restarted and adjusted to winter time.  
30 Oct 2010 [17:50:00]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 [17:30:00]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 [16:30:00]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 [15:30:00]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 [14:30:00]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 [14:00:00]A big day of work planned. Present were Rosie Ayton, Sam Ricketson, Hilary Costello, Tim Gale, Mark Rainer, Graham Newman, Hugh Hunt  
19 Oct 2010 [13:10:00]ADJUST: -400 ms/day to 43170  
02 Oct 2010 [15:05:00]ADJUST: +250 ms/day to 43570 witnessed by Cindy and Rob. Not sure why I should be doing this - the going was so good early in September and now it has gone all over the place. Perhaps time to look at the suspension spring... Rob, stickler for symmetry, had me put the regulation weights more evenly on each side of the pendulum shaft - maybe this will help!  
30 Sep 2010 [10:45:00]The pigeons are certainly back, caused a 30-second glitch  
25 Sep 2010 [08:45:00]A pigeon event, caused a glitch of 27 seconds  
16 Sep 2010 [09:45:00]The first pigeon event of the autumn. They are back. Damn. [link]  
13 Sep 2010 [08:00:00]Something happened here - after two weeks of beautiful steady going the amplitude has suddenly dropped and the clock is racing. I suspect the pendulum is touching something. Maybe the door to the case has blown itself closed?  
07 Sep 2010 [11:00:00]Wonderful steady going. The sudden pressure drop due to recent bad weather did not affect the going - barometric compensator working very well.  
07 Sep 2010 [10:45:00]Bill and Shirley Burbidge from Perth WA visited today. While waiting they saw two pigeons land on the minute hand at 11h45. They said that the minute hand bounced up and down as if it were on springs. Interesting that the two pigeons didn not cause a glitch. Maybe it takes three! I really need photographs...  
31 Aug 2010 [12:50:00]ADJUST: +120 ms/day to 43320 as witnessed by Sean Holden. The aim now is to be at zero for time change in October.  
06 Aug 2010 [22:00:00]correction +48 seconds for pigeon even of 29 July - see [link] - thanks Anson Cheung for doing this!  
05 Aug 2010 [07:15:00]ADJUST: +300 ms/day 43200ms  
03 Aug 2010 [06:20:00]A massive effect! One theory for why the pendulum only sometimes rubs the door of the clock case is that the lean of the tower varies with seasons and temperature. Ground water table variations will affect foundations (the post on my garden gate demonstrates this admirably). Also I estimate that the sun shining on the south-facing wall of the tower could cause a 5C temperature difference between the S and N faces, hence causing a lean, and 0.2mm shift in the position of the pendulum ...  
02 Aug 2010 [17:30:00]Restart computer after a power cut. Also opened the pendulum door a bit. Et voila! The going is now -300ms/day. Looks as if Graham-the-sleuth Newman hit the nail on the head. We will wait and see...  
01 Aug 2010 [22:00:00]Graham sensibly suggested that maybe the door of the pendulum case is rubbing on the pendulum - this would make sense as we closed the door firmly and locked it, where it was only partially closed before. This would reduce pendulum amplitude and hence speed the clock up  
29 Jul 2010 [07:50:00]Pigeon on minute hand, about 45 seconds duration, see [link] - corrected 6 Aug 2010  
24 Jul 2010 [17:40:00]Today we had a visit from the Antiquarian Horological Society - Turret Clock Group. More experts the clock has surely never seen. A good day was had by all. Afterwards Graham Newman and I tried to measure the diameter of the pendulum bob - without stopping it. I was holding the tape measure, but I guess I slipped ... hence the glitch on amplitude and drift.  
11 Jul 2010 [15:05:00]ADJUST: -100 ms/day 42900. This hot weather is doing something strange. Not surprised! Helped today by the Gunners: Vanessa, Alex, Melissa, Sumie and Chris.  
06 Jul 2010 [22:30:00]ADJUST: -100 ms/day 43000. Needed a bit more. Thanks to Eduardo, Cecilia, Zoran, Kai und Michael  
02 Jul 2010 [06:00:00]power cut caused logging system to shut down. Restart thanks to Tim Gale, the earlybird. Webcam was not restarted - we arere working on it.  
30 Jun 2010 [00:00:00]I think this sudden change in going is caused by a change in the direction of air flow up the pendulum chamber  
14 Jun 2010 [14:00:00]ADJUST: -250 ms/day 43100ms, Clearly I did not get this right. Try again (with the help of Jane, James, Maggie, Elsie, Naomi!)  
16 May 2010 [13:00:00]ADJUST: +30 ms/day 43350ms, getting fussy! I should really wait now to see what the barocompensator does.  
07 May 2010 [20:15:00]ADJUST: -50 ms/day 43320ms, just a little bit more...  
27 Apr 2010 [11:05:00]ADJUST: -130 ms/day 43370ms, this is a final adjustment (hopefully) after fitting of the barometric compensator. The clock is currently 0.14s fast and it would be great if it stayed that way for a few months ...  
15 Apr 2010 [22:00:00]can anyone explain why the pendulum amplitude should increase suddenly like this: [link] . It happens gradually over two hours from 10pm to midnight. The only thought I have is reduced friction on the escapement as the cable on the drum winds down from the second layer to the first, but if so then why does it not happen every week?  
08 Apr 2010 [00:00:00]removed the reference gradient lines for Going vs Pressure because the barometric compensator seems to be doing its job.  
30 Mar 2010 [11:05:00]introduced a plate to reduce airflow past the pendulum. There has been a step change in going - I wonder if this it related?  
28 Mar 2010 [11:20:00]ADJUST: -1500 ms/day 43500ms, bringing to -2600ms/day the total mass compensation for the barometric compensator  
28 Mar 2010 [00:15:00]ADJUST: -1100 ms/day 45000ms, necessary to compensate for the mass of the barometric compensator. Will need further adjustment in the morning.  
28 Mar 2010 [00:10:00]fitted a barometric compensator [link] , mass of compensator is 1.854kg, installed close to the pendulum flexure. As a guess, the CoG of the compnesator is between 2% to 5% away from the flexure towards the adjustment table, hence expect to have to remove about 20 to 60 grams of weight, equivalent to about 2000 to 6000ms/day  
28 Mar 2010 [00:05:00]plugged gaps under the floor boards to reduce air currents - and maybe to deter spiders.  
28 Mar 2010 [00:00:00]GLITCH clock advanced for summer time.  
25 Mar 2010 [09:00:00]GLITCH restart after another outage  
21 Mar 2010 [20:50:00]GLITCH logger restart after a power outage  
20 Mar 2010 [12:15:00]ADJUST: +100 ms/day 46100ms, and advanced 30 sec for pigeon event  
17 Mar 2010 [16:45:00]pigeon on the minute hand caused the clock to stop for 30 seconds  
07 Mar 2010 [12:00:00]After a College-wide power outage the computer system was restarted.  
05 Mar 2010 [06:48:00]Pigeon event (now that the sun is shining again). Reset by 54 seconds on Sat 6 March, 13h15  
23 Feb 2010 [12:15:00]ADJUST: -200 ms/day 46000ms (barometric pressure is forecast to stay low for several more days yet...)  
29 Jan 2010 [11:00:00]ADJUST: -300 ms/day 46200ms (settling down to a final value, still 100ms/day more than in summer 2009)  
23 Jan 2010 [20:00:00]ADJUST: +500 ms/day 46500ms  
23 Jan 2010 [19:30:00]The difficultly in setting the Going is, I think, due to air currents up and down the pendulum chamber. If air is flowing upwards then drag reduces effective g and in addition the amplitude increases. Both these effects slow the clock down. It may be that there is a switch between upflow in spring (warm air rises) and downflow in autumn (cold air is heavy). Note the step change in going around mid November.  
19 Jan 2010 [13:50:00]ADJUST: +500 ms/day leaving 46000 ms  
12 Jan 2010 [23:10:00]ADJUST: -200 ms/day leaving 45500 ms  
12 Jan 2010 [23:00:00]Unfortunately, the cardboard was gently touching the pendulum which caused a massive hike in the going. Corrected.  
12 Jan 2010 [12:15:00]Pigeon glitch correction of 36 seconds. Also put some cardboard baffles around the pendulum shaft in an attempt to reduce the updraft and downdraft that appears to be affecting the going.  
12 Jan 2010 [12:10:00]ADJUST: +700 ms/day (to 45700 ms of weights) - hope to be back to time next Tuesday  
09 Jan 2010 [13:45:00]More pigeons - twice (30 seconds stoppage) [link]  
08 Jan 2010 [14:50:00]ADJUST: -1000 ms/day (to 45000 ms of weights) - I want to get the drift back to near zero. It seems as if the winter going is faster than the summer going. Does this mean that the temperature compensation is not quite right?  
05 Jan 2010 [14:20:00]75sec correction for pigeon on 29 Dec  
05 Jan 2010 [14:15:00]ADJUST: -100 ms/day (to 46000 ms of weights)  
29 Dec 2009 [08:45:00]pigeon caused 75 second stoppage [link], corrected on 5 Jan.  
09 Dec 2009 [14:45:00]another pigeon caused 9 second stoppage [link] see photo at [link]  
08 Dec 2009 [10:45:00]pigeons stopped the clock for 4 minutes - this is getting serious! If you look closely you can see 3 separate pigeon events [link]  
07 Dec 2009 [10:45:00]pigeons on the minute hand, 30 second glitch [link]  
07 Dec 2009 [09:15:00]bumped the pendulum accidentally.  
05 Dec 2009 [07:45:00]another glitch [link] . BUT we now know what causes the glitches: Mr Down (a College Porter) saw a pigeon sitting on the minute hand. Indeed, the glitches always occur around hh:40 to hh:50 (when the minute hand is horizontal and rising) , and always in daylight hours. The pigeons are present on the dial in large numbers especially when the sun is shining - a warm south-facing place to sit [link] . A quick calculation: suppose two pigeon each weighing 1kg are sitting on the minute hand at a distance of 0.5m from the pivot, and so rising at about 1mm/sec. They requires 10mW of power to lift them (force*velocity). Then the 80kg _going_ weight falling 9m in 7 days generates 12mW of power (again force*velocity). So a power balance suggests that a pigeon or two can easily stop the clock.  
01 Dec 2009 [12:10:00]pendulum case in Dr Hopkinson s room opened, very noticeable downdraft. Caused clock to speed up - as expected from theory.  
24 Nov 2009 [09:50:00]glitch of 33 seconds, fixed at 13h00 same day [link]  
15 Nov 2009 [09:00:00]power outage caused data-logging PC to shut down (College disconnected due to works on the new electricity supply to the Kitchens). The weather station data (pressure, temperature, humidity) seems to have been permanentlly affected. Will need to be fixed.  
12 Nov 2009 [11:00:00]solar glazing installed, hopefully will help keep the sun from shining too hotly on the pendulum  
05 Nov 2009 [08:50:00]glitch of 9 seconds, [link] fixed 09h45 the following day  
03 Nov 2009 [18:35:00]glitch adjustment  
03 Nov 2009 [15:50:00]glitch of 30 seconds [link] . I think the cable of the going is jamming somewhere  
25 Oct 2009 [00:15:00]GLITCH End of Summer Time adjustment, clock advanced by 23 hours  
20 Oct 2009 [13:00:00]corection of 9s glitch, plus wind the clock, plus preparation for clock change on Sunday morning  
19 Oct 2009 [11:45:00]another glitch [link]  
09 Oct 2009 [13:30:00]GLITCH New GPS installed. Normal data gathering resumed.  
05 Oct 2009 [16:10:00]GLITCH GPS fault - data gathering halted. New GPS received on order.  
01 Oct 2009 [06:45:00]another .... [link]  
29 Sep 2009 [11:00:00]correction of 9s glitch plus attention to the freedom of movement of the weight cables - perhaps they are not sliding so freely against each other as they should, and a little freeing up was attempted.  
28 Sep 2009 [06:50:00]another glitch [link]  
27 Sep 2009 [09:43:00]yet another glitch in amplitude [link] , this time only 9 seconds in duration. What causes this? A real mystery.  
25 Sep 2009 [22:06:00]reset the time - interesting that it was only 1min40sec slow, even though the pendulum decay was over 3 minutes. The plot thickens!  
25 Sep 2009 [17:00:00]8 days later, the same has happened again. Almost identical drop in amplitude over 3 minutes.  
18 Sep 2009 [09:56:48]advanced clock by over 3 minutes - whatever it was that happened last night it stopped the clock for quite a while. Close inspection of the amplitude data shows that the escapement was _stuck_ for 3mins 20sec. Is there a big spider about? Or a rat?  
17 Sep 2009 [16:13:20]what on earth happened here? Amplitude dropped by 2 mm!  
15 Sep 2009 [12:45:31]during the winding I accidentally touched the pendulum - hence a glitch in amplitude. It should settle quite quickly  
31 Aug 2009 [10:39:00]ADJUST: +150 ms/day (back to 46100 ms of weights). This is because the clock has had a mean drift of around -150ms/day for the month of August, and has dropped 4 seconds. Curious, though, that the clock was actually 23 seconds slow today. I wonder if a mouse/rat gets into the fly and stops the escapement from time to time? Something seems to be happening. Really need a webcam!  
25 Aug 2009 [13:00:00]Is this another spider? The amplitude has dropped for a few hours, no particular feature in meteo properties.  
21 Aug 2009 [13:30:00]GLITCH Computer restarted, thanks to Sam Wenham and Rick Lupton  
30 Jul 2009 [14:00:00]GLITCH PC FAILURE - no data available until further notice. Sorry!  
19 Jul 2009 [10:20:00]ADJUST: -150 ms/day (to 45950 ms of weights). The clock has crept to 3.4 seconds fast and is averaging 50ms/day fast. I hope now to drop 100ms/day for 30 days to bring the clock back in line, but who knows what the weather will do - and the spiders.  
14 Jul 2009 [08:45:00]ANNUAL SERVICE by Smith of Derby (Jonathan Lee and Matthew Smith). I asked them not to interfere with the escapement or the pendulum. They investigated weights scraping against the stonework during winding, found that the First Strike (Trinity Strike) was scraping. They will make a minor adjustment. Also invesitgated the uneven winding of the Going line on the Going drum. We tried refitting the line at the ratchet end but found that the line then interfered with the quarters advancing bar. General service involving oiling and a check over. As a result, pendulum amplitude has dropped. I wonder if it will recover?  
07 Jul 2009 [04:26:40]another amplitude glitch. We really need a webcam looking for spiders!  
04 Jul 2009 [19:35:00] 1100 ms/day removed briefly to check calibration  
03 Jul 2009 [11:00:00]... no further adjustment necessary (a pleasant surprise)  
02 Jul 2009 [17:00:00]replaced miscellaneous washers with calibrated brass weights (courtesy Gareth Ryder who has also made a nice box for them). It was not possible to get the weight exactly right so I suppose an adjustment will be needed tomorrow, or over the weekend after the amplitude has settled down.  
15 Jun 2009 [09:30:00]ADJUST: -130 ms/day (to 46100 ms)  
11 Jun 2009 [13:45:00]GLITCH Logging interrupted to install UPS.  
08 Jun 2009 [04:00:00]... another spider? What caused the 1mrad (=1mm) drop in amplitude at 4am, recovered 2 hours later?  
19 May 2009 [15:44:38]Another curiosity is that small changes of Going vs Amplitude [link] shows a positive slope - not sure why. And there seem to be clusters - as if behaviour changes quickly and sits still for a while. The normal physics of a pendulum [link] predicts a negative slope, as here [link] so there is something more subtle going on. Maybe the spider again?  
19 May 2009 [14:58:20]Just a general remark, it has been noticeable over the last few days that pendulum amplitude forms a nice linear relationship with air density. This fits perfectly with a 0.5*rho*V^2 drag law. see [link]  
19 May 2009 [12:05:00]clock wound at 1.05pm - note the small glitch in amplitude, perhaps opening the clock case causes air currents that causing a small change in pendulum motion. Or maybe the act of winding moves the clock bed slightly causing the pendulum to be disturbed.  
17 May 2009 [00:00:00]... and why has it suddenly changed back at midnight? There is no change in anything else - some physics not accounted for here!  
14 May 2009 [23:30:00]What caused this gradual change in going, over 8 hours before and after midnight?  
12 May 2009 [12:05:00]clock wound at 1.05pm. temp is stable and going seems to be spot on zero. Might this last until October now?  
06 May 2009 [09:00:00]the spider again? Things settle down well after this - back to normal and very good running.  
03 May 2009 [16:00:00]very strange event, amplitude dropped by 1mrad so clock sped up by 1s/day, corrected itself the next morning. Could this have been a spider spinning its web between the pendulum and the casing? This is a really good event to plot as Going vs Amplitude becvause it obeys the pendulum physics beautifully. [link]  
01 May 2009 [13:00:00]ADJUST: +80 ms/day (to speed the clock up)  
15 Apr 2009 [01:00:00]clock stopped due to lack of winding  
20 Mar 2009 [14:26:11]Clock logger started - this is where the fun begins  
02 Feb 2009 [15:10:55]Smith of derby come in to tidy up the cables so that 7-day running is possible. Overall they have not paid much attention to the objective here. I doubt we will be working with them for much longer.  
14 Jan 2009 [15:09:47]NO! the clock stops about half a day short. Smith of Derby are not impressive.  
07 Jan 2009 [15:08:33]Clock restarted after 5 weeks of silence. Hopefully the clock will run for a week...  
03 Nov 2008 [15:06:28]Smith of Derby stop the clock for 4 weeks in order to convert the clock to 3-line running so that it will run for 7 days between winds.  
01 Oct 2008 [15:02:18]Rick Lupton starts his MEng project to create this web-based clock logging system  
01 Oct 2005 [14:59:29]James Strachan completes a summer project working on an optic sensor for monitoring the clock  
01 Jun 2005 [14:57:18]GianCarlo Pacitti completes his MEng project on clock monitoring using a microphone to measure ticks  
20 Feb 2004 [12:00:00]Council Minute 2004.61(b), Dr Glauert is thanked for 20 years of service looking after the clock and Dr Hunt takes over. 

Trinity College, Cambridge 2014