John Harrison's 250 year old clock design becomes record holder.

Wibbs

Article here

"One of Guinness World Records’ more unusual awards was presented at the National Maritime Museum yesterday. After a 100-day trial, the timepiece known as Clock B – which had been sealed in a clear plastic box to prevent tampering – was officially declared, by Guinness, to be the world’s “most accurate mechanical clock with a pendulum swinging in free air”"

Over a hundred days it lost 5/8ths of second in that time. :eek: To put that in context, vanishingly few non GPS updated quartz watches will be that accurate. Actually, sorry, none. Keeping under twenty seconds per year is a very accurate quartz watch, under ten is extremely accurate. Under three? Good luck. You're getting that with thermocompensation, twin oscillators and such like, or by revving up the speed of the quartz oscillator. IIRC the Omega Marine Chronometer of the mid 1970's which ran at 2.4mhz was within ten seconds per year and is still one of the most accurate standalone wearable timepieces to this day. It was also the first wristwatch to match Mr Harrison's shipboard chronometers of 250 years previously.

IMHO it's a pity that the advent of cheap quartz, people not really being too pushed on extreme accuracy and the mechanical revival(which cheapened quartz further) majorly impacted on the drive for ever increasing accuracy in standalone wristwatches. A drive which was the aim of every innovation and design of the great watch designers and marques from when someone first jammed a verge movement into something the size of an egg you could carry with you.

Either way kudos to Johhny boy. Amazing achievement to add to the list he had when he was alive.

coylemj

Harrison's clocks solved the problem of calculating longitude at sea for which you need to know the current mean solar time at a given location, hence the requirement for an accurate clock on board ship. In everyday (terrestrial) life there is no requirement for that kind of accuracy and while quartz watches may not be as accurate as their mechanical rivals, they do allow you to change to/from Summer Time without affecting the second hand, this pretty well levels the playing field so the more accurate mechanical watch ends up providing no great advantage to it's owner.

It's mentioned in that Guardian article (link above) but the book 'Longitude' by Dava Sobel is a cracking read for anyone interested in the challenge which Harrisson took up and for which he was (eventually) recognised.

blindsider

Great thread.

Sobel's book really is a great, and drolly humorous read. It's accessible, and not too long....well worth it.

Wibbs

coylemj wrote: »

In everyday (terrestrial) life there is no requirement for that kind of accuracy

Oh sure, hence ever increasing accuracy was sidelined for pretty good accuracy, which of course was significantly cheaper.

and while quartz watches may not be as accurate as their mechanical rivals,

You'll find you have that very much backwards C, if you are talking about wristwatches, as it seems you are.

Quartz watches are far more accurate than mechanical watches. The finest COSC chronometer rated mechanical doesn't come within an asses roar of a 20 quid Casio quartz. EG the COSC rates for a mechanical to pass are +6/-4 seconds per day. This means a mechanical chronometer could be over two minutes a month out of true and still pass. Tuning fork watches like Accutrons would easily best that. The last of the tuning forks were advertised at under a minute per month and under ten seconds per month is not unusual.

Put it another way, the COSC rates for a quartz chronometer are +/- 0.07 seconds per day, that's two seconds per month. Massive difference in accuracy. Though as I said even a crappy twenty quid quartz won't be too far off that. Quartz also have no positional error and are affected far less by shocks and magnetism. When the very first quartz movements were entered into the old chronometer competitions they pretty much signed the death knell of those competitions as they were getting near perfect scores based on the old mechanical benchmarks.

they do allow you to change to/from Summer Time without affecting the second hand,

Depends entirely on the quartz movement involved. Most don't have this facility.

this pretty well levels the playing field so the more accurate mechanical watch ends up providing no great advantage to it's owner.

Again the mechanical movement is not more accurate. I'm only labouring the point on this C as I've read similarly on more than one forum and article online. I have no idea where this idea came from TBH. Maybe from the marketing of "mechanical is superior"?

Now specialised scientific mechanical chronometer pendulum clocks can be more accurate than even the better quartz wristwatches, as Harrison has proved and proved back in the day, but not on the scale and tech of a wristwatch. Not yet anyway. Could it be done? Possibly, but again the will doesn't seem to be there. COSC levels are considered good enough for most. Consider that even a top line marque like Patek Philippe don't even "hack"(when crown is in setting position the movement stops) to accurately gauge the accuracy and if you read any independent accuracy tests on some very expensive watches few enough are even hitting the COSC rates. You'll also note that mechanical watch marketing very rarely mentions accuracy anymore. Rolex and their "superlative chronometer" rating would be about the most visible. They know that outside of over enthusiastic and imaginative owners quartz is king on this metric.

As an aside the Swiss COSC is a bit bogus a test anyway. They only rate raw movements not whole watches. The Observatory testing procedure in Neuchatel required whole watches, lasted much longer and had more tests. Again when the first quartz came out they blasted through this test too. When Girard Perregaux entered twenty examples of their first quartz it they scored the best of any watch they had so far tested. IIRC the last major model to go through the observatory test was Omega's megaquartz Marine Chronometer(the only wristwatch to ever get that official rating). Indeed if you have one of those I think you can still write to them with the serial number and they'll send you the original results of your watch.

It's mentioned in that Guardian article (link above) but the book 'Longitude' by Dava Sobel is a cracking read for anyone interested in the challenge which Harrisson took up and for which he was (eventually) recognised.

I'd agree 100% with you here C Great read. There are a few documentaries and drama docs on Youtube too IIRC.

Wibbs

Here's some cool video of the clock in question 280 days after the clock was set and the case was sealed.

https://www.youtube.com/watch?v=kOVEfddEAHY

Spookily on time. :eek: That's mad Ted. Displays the seconds one at a time too, like a long case clock and more like a stepping motor quartz than mechanical wristwatch. I find there's something restful about the one tick a second old clock. 60 beats per minute, like a resting heart rate. Not mine mind you, mines more a high beat movement, bordering on tuning fork

I love Harrisons Grasshopper escapement, a version of which is in this clock. Very cool looking and with very low friction(prone to overrun though).



As used in the Corpus Christi clock.

https://www.youtube.com/watch?v=cCqGtvTA36k

Just as there are rare quartz that sweep, there is a type of complication of mechanical watch movements that ticks once per second like the majority of quartz' but the name escapes me. I've seen both pocket watch and wristwatch(much rarer) examples. Apparently aimed at the Asian market back in the day, because they didn't like the normal sweep going on.

peasant

seenashow the dark, damp evenings are back ... here's Harrison on youtube
(for those that haven't seen this yet)

HeidiHeidi

blindsider wrote: »

Great thread.

Sobel's book really is a great, and drolly humorous read. It's accessible, and not too long....well worth it.

It was a 99p special on the Amazon Kindle store the other day.

I got it, not sure if it's still available, but having read it before I'd also recommend it, it's a fascinating read.

Valetta

Del Trotter got £6 Million at Sotheby's for it back in the nineties.

Bus Boy

Thanks for the link Peasant. Read the book and have been to the National Maritime Museum a few times. Was there in January when they had a special exhibition for them and lectures every hour. He really was a genius, and he was 'only a carpenter' as we were reminded every 2 minutes.

Bruthal

Wibbs wrote: »

I love Harrisons Grasshopper escapement, a version of which is in this clock. Very cool looking and with very low friction(prone to overrun though).

Its an interesting one alright, one I might get around to having a go at, at some stage. It has more potential problems than a graham escapement. Less friction alright, but does have some potential for mishap. Its nice and quiet though, and who can argue with its accuracy.