So, you made your statement. May we get a good look at the clock, please? And, perhaps an explanation of its mechanical feature that Mr. Harrison invented?
It's based on an 18th century theory because Harrison knew the necessary conditions for the pendulum to be isochronous. However it was rather impractical for use in regular clocks, so at the time it wasn't taken up.
Another thing I *think* he invented, was the “gridiron” pendulum, with a rod made up of many rods of opposing metals, so that some shrink while others expand with temperature changes, hopefully canceling each other out and thus keeping the pendulum’s length (and thus rate) constant despite temperature changes.
There is no metal that shrinks with increasing temperature, but the rods are arranged in a way that they expand in opposite direction so while a couple expand downward the others expand upward thus keeping the same the lengh of the pendulum arm. On a side note an even more precise clock with a similar concept used in astronomical observatories was fitted with a glass cylinder filled of mercury as the weight for the pendulum so with increasing temperature the mercury expanded very precisely like in a thermometer and so accomplishing the same result of keeping the point of balance at constant lengh
@@XMarkxyz It must have been difficult to get the column of mercury rising further up the pendulum to cancel the lengthening effect and keep the center of mass as constant as possible.
Yes but not servicing the clock after several years would make it no longer work correctly and eventually stop it, also not servicing clocks can damage them. It would have had to be stopped, serviced and possible repaired several times in those three centuries. :)
He also made clocks completely of wood ... the one in our family was still working last time it was spotted. Not to mention using clocks to create music ... Lucy timing.
Things like this makes me think the steam puck sci-fi worlds people create ae not really all that far fetched, an invention like this realised 150 years ago and mechanical devices would likely have been at an unimaginable stage today.
While that is true, the development of the computer was a fundamentally more important invention, as any electro-mechanical control device can be accomplished with much more efficiency and precision with digital controllers and processors than Rube Goldberg mechanical devices
Myanameis Beestingz Oh no doubt, but high capacity, compressed air revolvers and steam punk exoskeletons run on a crazy wood gassifier strapped to the mechs back does have it's own kind of special charm ^^
@@Karma8Kami Yeah there's a book called the Difference Engine which supposes Charles Babbage's ideas were implemented in the 19th century and brought about the computer age 100 years early via mechanical computers.
John Harrison is my hero, he is one of the greatest men of all time from Lincolnshire. He should have been compensated by the Board of Longitude, if he was them maybe he would have had enough encouragement to complete his accurate clock. We owe a debt of gratitude to Martin Burgess, his contemporaries and Donald Saff at proving John Harrison's greatness.
I think some of the key is in the “grasshopper” escapement Mr. Harrison invented. There should be some videos about this escapement elsewhere on RUclips.
I love that Horology lost 150 years just by ignoring Mr. Harrison, like the science of timekeeping was too full of itself to recognise a new idea. They could have very well struck out against the Quartz Crisis with this and they could not because they did not. I hope that last century or two was an educational one.
how can a pendulum with a fixed radius move in a cycloidal curve? are you talking about the accuracy lost due to the bump the pendulum gets from the gear to return to its starting position instead of following it's normal path of motion, which is required to keep its period mathematically regular?
To have a period of oscillation that doesn't depends on the amplitude of the pendulum (i.e. a second no matter if the pendulum lost energy over time), the end of the pendulum needs to approximate a sinusoidal path rather than a circular one. To do that, you just need a small oscillation angle/amplitude, if you zoom enough, a circle is very similar to a sine. What Harrison did was to use a bigger amplitude/angle, but the attach point of the pendulum also moves during the movement to compensate for it.
Family guy had a nice answer. When you learn the pendulum formula in physics class, that's an ideal pendulum. For small enough amplitude ( how far it swings,) the period only depends on the length and gravity. When I say only depends on length and gravity, we are ignoring external effects like air currents, and temperature ( which can change the length of the pendulum.) This clock uses the ideas mentioned by familyguy999 and has a few more ideas. The clock uses a grasshopper escapement to regulate the movement, which is not the standard pendulum escapement ( you can google how it works.) The grasshopper is a low friction device, which means the escapement can be run without oil, which would have an effect as it ages, and due to temperature. It uses something called a remontoir ( sp?) which keeps the escapement powered, without the downsides associated with it being powered from the rest of the movement. Normally, the escapement locks and unlocks the movement while at the same time, getting a bit of energy from the movement from it's own power, such as a spring or pendulum. But there's downsides to that, so it's powered by a smaller remontoir spring, which is automatically kept "wound" by a mechanism driven from the clock's power source, for example a pendulum. That's all the info I have, and sorry if I explained it poorly.
@@FamilyGuy999 Indeed, Harrison's pendulum design is not a fixed radius due to what you have said about its attachment. As far as the grasshopper escapement, the lignum wood material he used eliminated the need for periodic lubrication of the escapement mechanism.
The pendulum suspension; a thin flat spring or silken thread, instead of hanging free, swings between cycloidal cheeks or arcs, the pendulum then swings in the involute of a cycloid, which by mathematical coincidence is also a cycloid. By this means Harrison was able to use a much larger pendulum swing than otherwise could be used. A circular pendulum suffers from "circular error", where different amplitudes have different times of swing. This change of period is smaller for small circular arcs and this is the solution usually adopted. A cycloidal pendulum has theoretically equal periods for different amplitude so a bigger swing can be used. The other solution is to keep the amplitude absolutely constant, which is the solution adopted by Philip Woodward in his clock W5 which also easily beat the 1 second in a hundred days accuracy.
The presenter is a bit inaccurate Harrison did not come up with the idea of calculating longitude by means of a time difference, which he implies. That should not detract from Harrison's work.
So true. This is a problem in the U.S. also. So many brilliant minds are utterly turned off by the pomposity and 'Wokeness' of the upper class in universities these days that they avoid them like the plague.
Hmm. Firstly Harrison never made this clock 2 it uses materials not available to Harrison; advanced thermoplastics and most importantly an invar pendulum. 3 It has no compensation for atmospheric pressure, which most horologists, including Philip Woodward (Who also made a better than 1 second in a hundred days clock.) would say is essential for this order of accuracy. So what conclusions can we draw from this clock, not much really, only that we can, in the 21st century, build a better pendulum clock, than 300 years ago and that the result of the 100 day test was probably a fluke.
Donald Sayers you are wrong in many ways. Harrison has invented a temperature compensation. It is called gridiron pendulum rod. Burgess has used Invar instead, because it is easier to get good results with it. 2. Harrison invented a technique to compensate for atmospheric errors. For this purpose he has used a pendulum with large swing amplitude and he has added cheeks to control the circular error. He feeds the clock with constant energy by using a remontoir. Then the amplitude of the pendulum is a function of air density which depends on air preasure. When the cheeks have the right proportions, then the atmospheric error and the circular error cancel each other out. Burgess uses this approach on his clock A and clock B. This is a demonstration of Harrisons theory and this is also the reason why his clock can show an accuracy which was before only reached when the pendulum is inside a vacuum chamber.
@@jorgkirchhof7225 great answer Jorg, thanks. That was my understand as well. They also kept his grasshopper escapement, which needs no lubrication, removing a source of error ( like how George Daniels co-axial did the same for wristwatches.)
@@jorgkirchhof7225 The gridiron pendulum exhibits slip stick phenomenon as the various parts change length to compensate, these lead to timekeeping which has well defined steps in the rate graph, you can't get 1 sec in a hundred days with a gridiron. So exactly what has been proved? It's not a direct copy of a Harrison clock and it uses different materials not available to Harrison. It only proves that Harrison's design principles were sound enough, but they were a dead end and not followed by subsequent clockmakers.
@@donaldasayers copy & paste of claims of Wikipedia articles where no cited sources exist is not a good idea. You cite wrong. The wikipedia article about Gridiron pendulum talks about disadvantages and mixes up two things. First the friction in the holes: this has been discovered at old gridiron pendulums where corrosion lead to blocking (read e.g. Derek Roberts "Precision Pendulum Clocks - The quest for accurate timekeeping". These described "jumps" are a problem of some zinc iron gridiron pendulums. Zinc itself delivers these jumps when the zinc has bad purity. In serious books about precision pendulum clocks this is very well explained.
So, you made your statement. May we get a good look at the clock, please? And, perhaps an explanation of its mechanical feature that Mr. Harrison invented?
It's based on an 18th century theory because Harrison knew the necessary conditions for the pendulum to be isochronous. However it was rather impractical for use in regular clocks, so at the time it wasn't taken up.
Another thing I *think* he invented, was the “gridiron” pendulum, with a rod made up of many rods of opposing metals, so that some shrink while others expand with temperature changes, hopefully canceling each other out and thus keeping the pendulum’s length (and thus rate) constant despite temperature changes.
There is no metal that shrinks with increasing temperature, but the rods are arranged in a way that they expand in opposite direction so while a couple expand downward the others expand upward thus keeping the same the lengh of the pendulum arm.
On a side note an even more precise clock with a similar concept used in astronomical observatories was fitted with a glass cylinder filled of mercury as the weight for the pendulum so with increasing temperature the mercury expanded very precisely like in a thermometer and so accomplishing the same result of keeping the point of balance at constant lengh
Harrison was not rewarded well. The British navy effectively reneged on its promise of a reward.
@@XMarkxyz It must have been difficult to get the column of mercury rising further up the pendulum to cancel the lengthening effect and keep the center of mass as constant as possible.
@@Mars-zgblbl It was not the navy (Admiralty) who stiffed him; it was the Board of Longitude who was playing politics.
At a rough guess, if this were built when Harrison invented it and kept running continuously, it would have lost about 15 minutes by now.
Yes but not servicing the clock after several years would make it no longer work correctly and eventually stop it, also not servicing clocks can damage them. It would have had to be stopped, serviced and possible repaired several times in those three centuries. :)
Get the book Longitude!!! Excellent work all about Harrison and his chronometers. Guaranteed wonderful read!
Fantastic accuracy.
that's it? that just got me interested, and then none of it was explained. how does it work?
It use atom maybe 🤔
@@elonmusk42 It's 300 years old...🤦
He also made clocks completely of wood ... the one in our family was still working last time it was spotted. Not to mention using clocks to create music ... Lucy timing.
Things like this makes me think the steam puck sci-fi worlds people create ae not really all that far fetched, an invention like this realised 150 years ago and mechanical devices would likely have been at an unimaginable stage today.
While that is true, the development of the computer was a fundamentally more important invention, as any electro-mechanical control device can be accomplished with much more efficiency and precision with digital controllers and processors than Rube Goldberg mechanical devices
Myanameis Beestingz
Oh no doubt, but high capacity, compressed air revolvers and steam punk exoskeletons run on a crazy wood gassifier strapped to the mechs back does have it's own kind of special charm ^^
are*
@@Karma8Kami Yeah there's a book called the Difference Engine which supposes Charles Babbage's ideas were implemented in the 19th century and brought about the computer age 100 years early via mechanical computers.
On the one hand, yes; on the other hand, there is something to be said for processing that is completely parallel (not serial) and also mechanical.
John Harrison is my hero, he is one of the greatest men of all time from Lincolnshire. He should have been compensated by the Board of Longitude, if he was them maybe he would have had enough encouragement to complete his accurate clock. We owe a debt of gratitude to Martin Burgess, his contemporaries and Donald Saff at proving John Harrison's greatness.
I believe he was eventually given the full prize, but he was very old by the time the reward was paid.
I think some of the key is in the “grasshopper” escapement Mr. Harrison invented. There should be some videos about this escapement elsewhere on RUclips.
I love clocks and horology. Obsessed is more like it. This is beautiful..
It is covered thouroughly in the book 'Harrison Decoded': towards a perfect pendulum clock'. Oxford University Press 2020
Sorry but the 'theory' wasn't dismissed at the time, it was the idea of a precision clock made of wood which this clock isn't.
cc: Clickspring, who might find this interesting..
nice to see another who knows of him
John Harrison, the forgotten man.
People who read the book "longitude" know what's up
I love that Horology lost 150 years just by ignoring Mr. Harrison, like the science of timekeeping was too full of itself to recognise a new idea. They could have very well struck out against the Quartz Crisis with this and they could not because they did not. I hope that last century or two was an educational one.
how can a pendulum with a fixed radius move in a cycloidal curve? are you talking about the accuracy lost due to the bump the pendulum gets from the gear to return to its starting position instead of following it's normal path of motion, which is required to keep its period mathematically regular?
To have a period of oscillation that doesn't depends on the amplitude of the pendulum (i.e. a second no matter if the pendulum lost energy over time), the end of the pendulum needs to approximate a sinusoidal path rather than a circular one. To do that, you just need a small oscillation angle/amplitude, if you zoom enough, a circle is very similar to a sine.
What Harrison did was to use a bigger amplitude/angle, but the attach point of the pendulum also moves during the movement to compensate for it.
Family guy had a nice answer. When you learn the pendulum formula in physics class, that's an ideal pendulum. For small enough amplitude ( how far it swings,) the period only depends on the length and gravity. When I say only depends on length and gravity, we are ignoring external effects like air currents, and temperature ( which can change the length of the pendulum.) This clock uses the ideas mentioned by familyguy999 and has a few more ideas. The clock uses a grasshopper escapement to regulate the movement, which is not the standard pendulum escapement ( you can google how it works.) The grasshopper is a low friction device, which means the escapement can be run without oil, which would have an effect as it ages, and due to temperature. It uses something called a remontoir ( sp?) which keeps the escapement powered, without the downsides associated with it being powered from the rest of the movement. Normally, the escapement locks and unlocks the movement while at the same time, getting a bit of energy from the movement from it's own power, such as a spring or pendulum. But there's downsides to that, so it's powered by a smaller remontoir spring, which is automatically kept "wound" by a mechanism driven from the clock's power source, for example a pendulum. That's all the info I have, and sorry if I explained it poorly.
@@FamilyGuy999 Indeed, Harrison's pendulum design is not a fixed radius due to what you have said about its attachment. As far as the grasshopper escapement, the lignum wood material he used eliminated the need for periodic lubrication of the escapement mechanism.
The pendulum suspension; a thin flat spring or silken thread, instead of hanging free, swings between cycloidal cheeks or arcs, the pendulum then swings in the involute of a cycloid, which by mathematical coincidence is also a cycloid.
By this means Harrison was able to use a much larger pendulum swing than otherwise could be used.
A circular pendulum suffers from "circular error", where different amplitudes have different times of swing. This change of period is smaller for small circular arcs and this is the solution usually adopted.
A cycloidal pendulum has theoretically equal periods for different amplitude so a bigger swing can be used.
The other solution is to keep the amplitude absolutely constant, which is the solution adopted by Philip Woodward in his clock W5 which also easily beat the 1 second in a hundred days accuracy.
@@FamilyGuy999 The shape of the path of the pendulum should be cycloid not sinusoid.
What clock brand?
How were they able to determine Harrisons' H4 clock was accurate to one second a month?
The presenter is a bit inaccurate Harrison did not come up with the idea of calculating longitude by means of a time difference, which he implies. That should not detract from Harrison's work.
Have a nice day
because class bigotry got in the way as it did (and does) so often in the british isles
So true. This is a problem in the U.S. also. So many brilliant minds are utterly turned off by the pomposity and 'Wokeness' of the upper class in universities these days that they avoid them like the plague.
A problem evident in comments elsewhere to this video😂
I prefer the *sun*
That's great when you can see the sun. Which is not true at night, nor on overcast days
Not helpful if you don't know your longitude.
Which sun completes it's revolution in 365.24 days
i like this
How is the number -7/8?
Fridericus Rex -0.875 seconds per day
@@AH-yg2dj rather, -0.8 s per 100 days : -0.008 s per day.
Can you do who can hold there breath the longest
@ Black Order: How long can you watch youtube videos without writing stupid comments?
>tfw the English dude looks like a stereotype
Those teeth could also be in the book!
It's actually from the Serbian king
8
more blah blah blah and more about the presetnters, yet no real photos of the clock just bits and carefully removed detail. 👎🙁👎🙁👎🙁
Dreadful waste of time...
6th boi
Hmm. Firstly Harrison never made this clock
2 it uses materials not available to Harrison; advanced thermoplastics and most importantly an invar pendulum.
3 It has no compensation for atmospheric pressure, which most horologists, including Philip Woodward (Who also made a better than 1 second in a hundred days clock.) would say is essential for this order of accuracy.
So what conclusions can we draw from this clock, not much really, only that we can, in the 21st century, build a better pendulum clock, than 300 years ago and that the result of the 100 day test was probably a fluke.
Donald Sayers you are wrong in many ways. Harrison has invented a temperature compensation. It is called gridiron pendulum rod. Burgess has used Invar instead, because it is easier to get good results with it. 2. Harrison invented a technique to compensate for atmospheric errors. For this purpose he has used a pendulum with large swing amplitude and he has added cheeks to control the circular error. He feeds the clock with constant energy by using a remontoir. Then the amplitude of the pendulum is a function of air density which depends on air preasure. When the cheeks have the right proportions, then the atmospheric error and the circular error cancel each other out. Burgess uses this approach on his clock A and clock B. This is a demonstration of Harrisons theory and this is also the reason why his clock can show an accuracy which was before only reached when the pendulum is inside a vacuum chamber.
@@jorgkirchhof7225 great answer Jorg, thanks. That was my understand as well. They also kept his grasshopper escapement, which needs no lubrication, removing a source of error ( like how George Daniels co-axial did the same for wristwatches.)
Love the W5 Woodward clock . My own right time. great read. , also Accurate clock pendulums by Matthys , made a pendulum , just need a mechanism.
@@jorgkirchhof7225 The gridiron pendulum exhibits slip stick phenomenon as the various parts change length to compensate, these lead to timekeeping which has well defined steps in the rate graph, you can't get 1 sec in a hundred days with a gridiron.
So exactly what has been proved? It's not a direct copy of a Harrison clock and it uses different materials not available to Harrison. It only proves that Harrison's design principles were sound enough, but they were a dead end and not followed by subsequent clockmakers.
@@donaldasayers copy & paste of claims of Wikipedia articles where no cited sources exist is not a good idea. You cite wrong. The wikipedia article about Gridiron pendulum talks about disadvantages and mixes up two things. First the friction in the holes: this has been discovered at old gridiron pendulums where corrosion lead to blocking (read e.g. Derek Roberts "Precision Pendulum Clocks - The quest for accurate timekeeping". These described "jumps" are a problem of some zinc iron gridiron pendulums. Zinc itself delivers these jumps when the zinc has bad purity. In serious books about precision pendulum clocks this is very well explained.
Second
1st
No you're not dumbass
Such like a brat
Go ahead, celebrate for being first yourself
FIRST
first