back to article Measure for measure: We visit the most applied-physicist-rich building in the UK

Shielded by lime trees in a quiet corner of south-west London, a low, modern building constructed of green glass sits on rolling lawns behind a high metal fence. It’s a discreet facility save for a huge white sign facing the road with an blue official crest and three large letters that spell out NPL – the National Physical …


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  1. bitmap animal
    Thumb Up

    It's a great place

    Thank you for a fantastic walk-around, what an awesome place. I've wanted to visit for some time but not managed to tie up an open day. They have an annual water rocket challenge which is next Wednesday.

    It's a nice part of the world too, Bushy Park backs onto it and I can confirm Teddington has a couple of lovely coffee shops.

  2. Neil Barnes Silver badge

    I suspect

    that therein may be one or two boffins!

    1. AndyS

      Re: I suspect

      How much Boffinry though? Come on Lester, we expect the exact answer to the nearest deci-Pyke.

  3. Anonymous Coward
    Anonymous Coward

    Peak pedantry

    Peak != peek (nor pique nor Peke)


    1. Gordon 10

      Re: Peak pedantry

      I presume you used the send corrections link?

      /correct procedures pedant

      1. Mephistro

        Re: Peak pedantry

        "I presume you used the send corrections link?"

        Oh, come on! If everybody did that, poor Ed - you know, that guy who writes snarky comments inside other people's articles- would find himself unemployed, you insensitive clod!

  4. John Smith 19 Gold badge

    NPL also came up with a machine to machine surfaces to 1nm in a factory environment

    It was pyramid shaped and used special rubber bearings at it's corners as well as a "squeezed metal" precision actuator they called a "Poison pusher."

    Sadly it's core developer died young and AFAIK it sank without trace.

  5. Alister

    Surely the pic of the Spitfire is upside down???

    1. Chris Holford

      It's the Schneider Race seaplane; It's upside down so that 'lift' forces act downwards and can be measured as an INCREASE in the load on the supports it is hanging from.

      1. Alister

        It's the Schneider Race seaplane

        Nope, it isn't, the S5 looked very different to that, particularly round the engine cowlings, it's a Spitfire.

        1. Vinyl-Junkie

          Definitely a Spit!

          Download and rotate the photo - clearly a Spitfire. Apart from the points noted above the lack of floats is a bit of a giveway...

        2. Matt Bryant Silver badge
          Thumb Up

          Re: Alister

          "... it's a Spitfire." Correct, and not a forerunner either. It's probably an aerodynamic mock-up of an early model as it has the top bulged canopy roof introduced on production MkI aircraft after pilots complained the flat-topped canopy meant they often banged their heads in bunts. Later models had a canopy that bulged out to the sides as well. Seeing as it has a single and shallow radiator, a round oil cooler, no cannon, a short nose with three-bladed prop in a small spinner, and small tail, my bet is a MkVa.

          The S6 also had SFA to do with the Spitfire - different wing design and different structure, completely different engine, different design philosophy (low-level sprint racer vs higher altitude interceptor), different systems (no radio, no oxygen, no retractable undercarriage, not even a seat with a parachute). The only value to the Spitfire project was the thrashing of the Rolls-Royce engine helped with later Merlins developments.

          1. Vinyl-Junkie

            The only value to the Spitfire project.....

            Not actually true. Without the work done on the Schneider trophy racers, in particular the S6/S6Bs, Mitchell would not have had the experience to design the Spitfire. Many of the things that went to make the Spitfire the aircraft it was (all metal construction, stressed metal frame, thin wings) were a result of his work on the Schneider Trophy racers. The Spitfire came directly out of that work; for proof see the last aircraft he designed which was not related to his Schneider work; the Walrus. An aircraft that did very well at what it was designed for, but a Spitfire it ain't!

            1. Matt Bryant Silver badge

              Re: Vinyl-junkie Re: The only value to the Spitfire project.....

              ".....Mitchell would not have had the experience to design the Spitfire...." Mitchell already had plenty of experience designing fighters to Air Ministry specifications and was already working on the Type 224 fighter proposal at the time of the S6B's race. The failure of the Type 224 in competition with the Gloster Gladiator was a much bigger impetus for the Spitfire. It has often also been pointed out that the Spitfire contained nothing new - the thin wing profile was not Mitchell's work and the elliptical planform had already been proven on the He70 Blitz; the Yanks had perfected all-metal monocoque construction years before; significant parts of the design, such as the 'jet-effect' radiator, were from the RAE - and that Mitchell's real genius was in combining those technologies into a single aircraft. But the actual lion's share of the Spitfire's development that converted it into a top fighter occurred after Mitchell's death in 1937, under the direction of Supermarine's Joe Smith, who receives little credit.

              ".....the last aircraft he designed...." Mitchell's last design was a four-engined bomber, the SupermarineType 317, not the Walrus.

              1. Vinyl-Junkie


                ....I said "the last aircraft he designed which was not related to his Schneider work" the Type 317 definitely had Schneider influences, whereas if the Walrus did they are not immediately obvious!

                I agree with you that Mitchell's genius was in combining those technologies into a single aircraft, but that was exactly what he had learnt to do whilst working on the ST racers. And had he not worked so successfully on those, would Supermarine even have trusted his radical designs enough to build a prototype?

                I, and almost any book on the subject you care to read, see the development of the Spitfire as being firmly grounded in the Schneider Trophy.

                1. Matt Bryant Silver badge

                  Re: Vinyl-junkie Re: Actually...

                  ".....the Type 317 definitely had Schneider influences...." Really, you want to try claiming that? Please do show me those 'influences' seeing as one was a minimalist, single-engined, floatplane racer and the other was a four-engined, long-range bomber. The wing design was completely different for a start.

                  ".....whereas if the Walrus did they are not immediately obvious!...." That's because the Walrus was a continuation of a design family going back to the commercial Sea Eagle amphibian and the Sea Lion racing flyingboats.

                  ".....And had he not worked so successfully on those, would Supermarine even have trusted his radical designs enough to build a prototype?...." Yes, because he had already demonstrated design skills on commercial aircraft for Supermarine. Indeed, when Vickers bought Supermarine in 1928 it was on condition that Mitchell stayed on as chief designer, he was already so highly regarded.

                  "....I, and almost any book on the subject you care to read, see the development of the Spitfire as being firmly grounded in the Schneider Trophy." You, and all the books you read, simply perpetuate the same myth. The S6.B was not nearly as radical as many like to make out, having wire-braced wings, whereas the Spitfire's were internally braced. The S6.B had horn-balanced ailerons whilst the Spit had Frise type. The S6.B used surface-radiators whilst the Spit had the RAE-designed 'jet' tubs. The S6.B's wing was a simple, short, constant chord design with no dihedral, giving a high wing-loading of about 42lb/square foot, whereas the Spit's was a complex, dihedral, elliptical design with retracting undercarriage and machineguns, that had a wing-loading of only 27lb/square foot. The S6.B was designed to fly at very low level for very short periods at high speed, whilst the Spit was designed to climb high and intercept bombers over hundreds of miles. It's like saying the design of a dragster influenced the latest Challenger tank.

  6. smudge

    When did computing & networking close?

    I worked there on a joint industry-NPL computing project in the late 1970s. Some famous names were still around, like Donald Davies (one of the inventors of packet-switching), Mike Woodger (assistant to Turing when here was there) and Brian Wichmann (programming languages, especially Ada).

    They were still doing interesting things in computer architectures and networking - but I assume that some review some time decided that this was better left to the private sector?

    1. Yes Me Silver badge

      Re: When did computing & networking close?

      I'm guessing that the old Mathematics Division morphed into

      You might like David Yates' book: D.M. Yates, Turing’s Legacy: A History of Computing at the National Physical Laboratory 1945–1995, Science Museum, 1997.

      Shouldn't there be a Turing icon available?

      1. smudge

        Re: When did computing & networking close?

        Thank you! I have just ordered a copy of that book.

  7. Felix Krull

    NPL gave us the atomic clock, but now it’s going further: working with laser-based time keeping to put an extra decimal point on the current definition of the second – defined as the rate at which caesium atoms flip when agitated by microwaves at a set frequency.

    That sounds suspiciously circular to me. How do you determine the microwave frequency without precise time-keeping in the first place?

    And how does an atom 'flip'?

    1. Mike Pellatt

      And how does an atom 'flip'?

      As you're clearly too lazy to use Google, I used it for you. The search term "cesium clock operation" seemed like a good one. The link to How Stuff works sort of explained it but in a woolly way, but a snippet from here explains the physics very succinctly:

      "The atoms in pure cesium exist mostly in two slightly different forms: A low energy form and one with just a bit more energy. For an atomic clock these two states have two properties critical to making a clock. One, they can be separated by a magnet. And two, the lower energy atoms can be converted to the higher energy ones if we bombard cesium with the right radiation."

      The process of converting to a higher energy is what's referred to as "flipping" And it's the frequency of this "right" radiation that determines a second. HTH, HAND, and all that jazz.

      1. proto-robbie

        Sorry, you're on the mark with your post, but need a downvote for repeated misspelling of the word "caesium". This is of course the British spelling, but it is after all an article about a British institution. Living in a different continent is no excuse.

      2. censored

        You've answered the flip bit but not the frequency bit, which I think is more important and I don't quite get either.

        The second is determined by the frequency of the flip of a caesium atom. But it seems in order to get the right flip, you use microwave radiation of a specific frequency. How do you know your microwaves are the right frequency?

        1. BenR

          I thought the same thing - suspciously circular reckoning going on!

          The second is determined by the frequency of the flip of a caesium atom. But it seems in order to get the right flip, you use microwave radiation of a specific frequency. How do you know your microwaves are the right frequency?

          However, having read the original response, I think the answer is that you don't define the frequency. You know that at some frequency, fx, the caesium will 'flip'. You therefore aim a microwave generator at the caesium, and increase the frequency until 'flipping' begins (which you presumably measure in some way - I'm guessing some kind of EM emission?). At which point, you know the frequency at which this is occurring, and thus can work out how long a second is? And rather than use the number of cycles in a second, you run the test over a long period of time and count the number of cycles to reduce the error, and then further reduce it by running many many many repeats of the test, then use Clever Maths (TM) to get to a final number?

 seems to explain it.

          I still can't quite get the idea that it's a bit circular out of my head, but I'm guessing the Uber-Boffins at NPL are much much much clever than me and know what they're doing. If it was as circular as it appears to my (our) brains, I'm sure the peer-reviewed journals would be filled with a lot more comments along the lines of "You're a pillock."

      3. Felix Krull

        As you're clearly too lazy to use Google, I used it for you.

        I googled 'caesium atom flip' and got zero hits on the first page. I didn't google caesium clock because I know how it works already. The only 'flip' I've heard about in nuclear physics is a spin flip, and atomic clock works on exciting atoms.

        The process of converting to a higher energy is what's referred to as "flipping"

        Only in this article.

        So thanks for taking the trouble answering, but thanks for nothing.

  8. Richard Rae

    Just saying....

    ..... It would be nice if the general populous looked at this country through the achievements of these kind of installations instead of the football failures, Big brother and other mind numbing society dumbing drivel that is the main entertainment.

    Maybe then they will actually have more respect for the place, themselves and what this nation has contributed to the world....

    1. Lars Silver badge

      Re: Just saying....

      On the other hand it might be better to look less at history and more on today and the future. The Spitfire was important and a fine plane if not superior in any way. A short range plane and useless in supporting bombers over Germany, I think the Mustang (with a British engine) then solved that problem.

      1. Matt Bryant Silver badge

        Re: Lars Re: Just saying....

        ".....A short range plane and useless in supporting bombers over Germany, I think the Mustang (with a British engine) then solved that problem." Yes, the Mustang (after Rolls-Royce fixed it) was arguably the best escort fighter of the War, but then the Spitfire was not designed for escort but as a fast-climbing bomber interceptor. The Mustang was never as good an interceptor as the Spit. The RAF Spitfires also escorted every 8th AF mission out and back from the Dutch coast, allowing the Mustangs to save their fuel and ammo for the stretch from there to Germany and back, so part of the Mustang's success was provided by the Spitfire. And then there are those that will point out that not only did the P-47D go to Berlin and back but did so with twice the firepower of the P-51B (eight vs usually just four .50s), but also that the 56th FG only used Thunderbolts and were the highest scoring fighter unit in the 8th AF.

        1. This post has been deleted by its author

        2. Lars Silver badge

          Re: Lars Just saying....

          @Matt Bryant, Yes, so, I did say important and fine no offence meant. No plane was perfect in every respect, that would be impossible. If I had to choose the best among the British from that period I would probably choose the Mosquito. This article was not about WW2 fighters or bombers but, as you know, comments tend to move in mysterious ways. There is a lot of interesting stuff about those plans on the net and on YouTube, including what was made elsewhere. Fascinating stuff, and those who are really into it don't feel unpatriotic if they appreciate what was made in other countries too. My "favorite" fighter would probably be the FW-190. Some of that here.

          Years ago I knew a fighter pilot from the war who once, rather drunk, suddenly said - you guys have no idea of how much shit there is in a human being. Much later we had to ask him about that and he told us that they had to pick up the pieces of the crew from friends and foes from planes that crashed in the neighborhood. He also told us that, very much against his own will, he shed a tear when he shot his first enemy pilot to pieces.

          Looking at those fine machines I try to remember why they where built and sometimes I feel movies about that period tend to be more romantic than the reality.

      2. Richard Rae

        Re: Just saying....

        every country has failures in their history. I was not talking about that, but more that the current thought process in this (and so many other countries) is more axed towards the belittling of the place and what people achieve as opposed to taking stock of what has, is and will be done.....

  9. phuzz Silver badge

    That anechoic chamber reminded me of the trip I took as a kid round the Matra Marconi plant. They have much larger anechoic chambers, where the foam spikes are impregnated with carbon which are used to test the radios and sensors of the satellites they build there.

    I remember one room was about the size of a small church, with almost every surface covered in enormous blue spikes, and that it was almost impossible to hear anyone from more than a few meters away.

    Worth a trip for future articles?

  10. Anonymous Coward
    Anonymous Coward

    This is scary

    I never heard of the NPL, but I happened to wander past them for the first time this weekend whilst looking for the right cricket ground (there is a veritable nest of them in that area, and NPL has one too).

    Are you guys tracking me? :)

    1. chrisf1

      Re: This is scary

      The chilli in the cricket club on the grounds used to be quite good too. Wonder if it's still there. My abiding memory of working in the Turing building was that the entire building resonated when Concorde flew over. At a frequency just below a telephone microphones ability to pick. Led to some peculiar phone conversations. Sadly I believe the building along with Concorde is no more.

  11. Anonymous Coward
    Anonymous Coward

    Technical pedantry

    The NPL can't have established "the" value for g, because it varies all over the Earth. It is measurably different at Cambridge from London. That's without including the effect of the Earth's rotation which reduces the apparent value of g depending how far you are from the Poles, or the effect of altitude. What's more, you measure it, you don't calculate it (except incidentally in converting the dimensions and period of your pendulum.)

    Perhaps the number you cite is the value that g would have if the Earth was a perfectly spherical, homogeneous solid. In which case, it's pretty useless for anything.

  12. Woodgie

    No mention of the length of a piece of string?

    I used to do some IT support for the boffins at NPL (and I'd like to take the opportunity to say what a fantastic bunch of chaps and chapesses they are!) and the one thing that I found amazing was they could - and WOULD - measure anything.

    I think the story goes like this (I heard it Nth hand): One of the boffins asked one of the designers how long a brochure or leaflet or somesuch would take to complete "Oh, well, how long is a piece of string?" came the reply. About a week later a small wooden box was delivered to the head of the design department containing a piece of string and an official certificate saying something along the lines of "A piece of string. Length: 97.914mm" and a typed note saying "So, how long until I get my brochure?"

    The story may well be apocryphal but I have a photo of the piece of string in its box and the certificate somewhere. (Though I may have misremembered the exact length, it was to 3 decimal places!)

    What a wonderful bunch!

  13. Irony Deficient

    The second, kelvin, ampere, candela and mole were ratified as standards in 1889.

    Gavin, by whom were these standards ratified in 1889? The CGPM in 1889 only ratified the International Prototype Metre and the International Prototype Kilogram. The name “mole” first appeared in 1902, and didn’t become a SI base unit until 1971. The candela as a unit was first proposed in 1909, and became a standard in 1948, replacing the slightly larger 1881 international candle. Similarly, the international ampere was defined in 1881, but was replaced by the slightly smaller absolute (now SI) ampere in 1948. The degree Kelvin (later kelvin) didn’t appear until 1954, and the second was defined (as 1/86400 mean solar day) long before 1889.

  14. Crisp

    It looks like an Aperture Science Testing Centre.

    See title.

  15. Anonymous Coward
    Anonymous Coward

    Old teddington

    visited 40 years ago - was interested to see, a model of the 'Dam Busters' in the trees, and the Newton apple - not in great condition then.

  16. Deebster

    "Like an ass whose back with kilograms of Concorde bows..."

    I cannot even parse this subtitle, unless it's "'like a donkey who has returned with many plane parts" - in which case I'm still confused.

    1. markw:

      Re: "Like an ass whose back with kilograms of Concorde bows..."

      Measure for measure.

      For, like an ass whose back with ingots bows,

      Thou bear's thy heavy riches but a journey,

      And death unloads thee. Friend hast thou none;

  17. DanX

    Re: Gravity... value

    So they have defined the constant g as 9.8118177 m/s/s but how accurate is that figure for actual use? +- 0.00000005 m/s/s

    Out of interest how much does gravity vary over the course of a typical day due to movements below the earths crust?

  18. DanX

    Re: Gravity... value

    Argh, or if an experiment is accepted to be the most accurate to they rework all the units so there is no error? My understanding of how constants and units are managed is not all good!

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