Category Archives: Metrication

The Americans Who Defined The Meter

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By The Metric Maven

On April 13, 1668 the metric system was born. It had been devised by the English scholar, John Wilkins (1614-1672). The system was elegantly defined. One would take a length of string with a mass attached, and adjust that length until the pendulum had a period of two seconds (one second each direction). Now that you had a standard length you would divide that by ten, and use that length to make a cube, which became the liter. Fill the cube with rain water and the mass is a kilogram.

This system was to be a “Universal Measure” that everyone could use. There was just one perceived problem, the period of a pendulum depends on its latitude, so a seconds pendulum would not be universal. The alternative, measuring a distance on the surface of the earth, was however, a very questionable alternative. James Clerk Maxwell (1831-1879) in his A Treatise on Electricity and Magnetism sums up the situation with the meter in 1873:

In…countries which have adopted the metric system, …[the base unit] is the metre. The metre is theoretically the ten millionth part of the length of a meridian of the earth measured from the pole to the equator; but practically it is the length of a standard preserved in Paris, which was constructed by Borda to correspond, when at the temperature of melting ice, with the value of the preceeding length as measured by Delambre. The metre has not been altered to correspond with new and more accurate measurements of the earth, but the arc of the meridian is estimated in terms of the original meter.

One can sense that Maxwell is satirizing the idea of a measurement unit based on the earth, and exposes the “earth based” meter as being essentially a defined artifact which is not exactly “universal.”

Maxwell had his own viewpoint of how a universal standard of length might be created:

In the present state of science the most universal standard of length which we could assume would be the wavelength in vacuum of a particular kind of light, emitted by some widely diffused substance such as sodium, which has well-defined lines in its spectrum. Such a standard would be independent of any changes in the dimensions of the earth, and should be adopted by those who expect their writings to be more permanent than that body.

Yes, it’s clear. Maxwell is not particularly keen on the current definition of the meter in 1873. Indeed light did seem to be the best option for a standard.

Charles Peirce

This is when the eccentric and abrasive American-born Charles Sanders Peirce (1839-1914) enters the story. Robert P. Crease, author of World In The Balance states:

“He was also one of America’s most important metrologists. He made precision measurements, and improved techniques for making them. His work helped remove American metrology from under the British shadow and put American metrology on its feet.”

Charles was introduced to a spectroscope, which is a device that separates light into its constituent frequencies, by Joseph Winlock of the Harvard Observatory. Spectroscopy was allowing scientists to identify the chemical elements which make up stars. The element helium was first identified as a yellow spectrum line seen during a solar eclipse of the sun in 1868, prior to its identification on earth. I suspect they thought it would probably be a metal given the ium suffix. With the help of his father, Charles became head of the Office of Weights and Measures in 1872. Peirce traveled to Paris in 1876 and brought back brass meter standard number 49, which would be used for the calibration of American standards.

The idea of using light for a standard had been contemplated for some time, but there was a potential problem. Light is a wave, waves travel through a medium (water for water waves, air for sound waves). It was thought that light traveled through a medium, which they called aether. It was believed that the wavelength of light would be altered because of the earth’s rotation in the aether and its solar orbit. This would be like the problem of a seconds pendulum having a different period depending on its latitude. Peirce was aware of this and is quoted by Crease on page 195:

[T]here may be a variation in wave-lengths if the aether of space, through which the solar system is traveling, has different degrees of density. But as yet we are not informed of such variation.

In 1887 the Michelson–Morley experiment failed to detect the aether. This caused a considerable scientific brouhaha, but the aether was not dead yet. It was too powerful of an idea. In the end, after repeated experiments failed to detect the aether, it was decided it must not exist, and light could be relied upon to be a universal standard for the definition of a meter.

One can create light which is produced by a known element by placing its gas inside of an evacuated tube. The tube can then be exited with electricity. We all know that when the gas is neon we call it a neon light, or neon tube. Peirce chose to use sodium for his tube. Peirce attempted to calibrate the distance between the  machined  lines on a diffraction grating, back to his number 49 meter standard using the sodium light. Unfortunately, the lines on the diffraction grating had imperfections that made the lines a bit fuzzy, which limited the resolution. The distance between the lines on the diffraction grating would change with temperature, further decreasing the accuracy. The accuracy of the thermometer he used to monitor the temperature also introduced error. Peirce published his results in 1879. He had tied the meter to a wavelength of light by way of the lines on the diffraction grating. He was the first to do this, but it was still not the method described by Maxwell, which involved counting wavelengths of light.

Illustration of Interferometer from Michelson and Morley’s Scientific American Paper

Albert Michelson read Peirce’s publication and realized that the interferometer he and Morley had developed to detect the ether could be used for the precise measurement of wavelengths which Peirce was pursuing with diffraction gratings. An interferometer splits a single beam of light in two and later recombines it so the two beams are out of phase. This produces a series of light and dark interference patterns. A screw is attached to a mirror that can be used to move the mirror and count the number of light and dark oscillations. Michelson and Morley published this work in 1888. The first sentence of the paper is: “The first actual attempt to make the wave length of sodium light a standard of length was made by Peirce.” The inaccuracies of his method  are described and the advantages of an interferometer are discussed.

They determined that it would take the counting of 400,000 wavelengths to obtain a decimeter (100 mm). Michelson and Morley suggest in their paper:

Probably there would be considerable difficulty in actually counting 400,000 wave lengths, but this can be avoided by first counting the wave lengths and fractions in a length of one millimeter and using this to step off a centimeter. This will give the nearest whole number of wave-lengths, and the fractions may be observed directly. The centimeter is then used in the same way to step off a decimeter, which again determines the nearest whole number, the fraction being observed directly as before.

In 1892 Michelson went to Paris to relate he and Morley’s interferometer work. Unfortunately, Michelson discovered that his sodium light did not produce a single frequency line but was actually a composite of two lines. This caused enough fuzziness to not allow for measurements which were as precise as he needed. Michelson tried both mercury and cadmium and settled on the latter.

In the 1906 book Outlines of The Evolution of Weights and Measures and The Metric System, the authors, William Hallock and Herbert Wade, state (pg 265) that Michelson used “three different kinds of light, viz. the red, green, and blue of the cadmium spectrum, he determined the wave-length of each or the number of times this wave-length was contained in the standard meter. The wave-lengths for each color were as follows:”

Hallock and Wade can hardly control their enthusiasm and excitement at this technical breakthrough:

The accuracy of this work is almost incredible, as the variation in measurements was only about one part in ten million. …..here is an absolute measurement which gives the length of a standard in terms of a natural unit, under conditions reproducible at any time. This, of course, gives a permanent check on the integrity of the meter, as in the event of the international prototype being damaged or destroyed……

It was decided by the participants that pursuing a method of tying the natural phenomenon of light to the meter was to be undertaken. Charles Fabry and Alfred Perot made improvements to Michelson and Morley’s interferometer, and were able to obtain a precision near that of their artifact standard. Improvements to the interferometer continued.

A survey of candidate elements was undertaken to find the best one to use for a new standard for the meter. This uncovered the fact that various isotopes of the elements were emitting light at different wavelengths which caused blurred lines. The search was on for elements that were heavy and had few isotopes. This work continued throughout the 20s and 30s. World War II delayed progress, but in the 1950s enough improvements had been made to schedule a re-definition of the meter in 1960. By international agreement the meter was defined in terms of the wavelength of light emitted by the krypton–86 isotope. The meter was now a length available to all countries without respect to an artifact or geography.

Despite the fact that Peirce, Michelson, and Morley—all American scientists—were instrumental in achieving the dream of a universal meter available to all, America did not convert to the metric system or metric lengths. Even though the lengths used in the US: the inch, foot, yard and mile, are all defined by the meter, America rejects a system of length first defined by an Englishman, and then made universal by Americans. I find great irony that most Americans believe that German Chocolate Cake is of Germanic origin. This is not the case. It was created by Sam German—an American—in the 19th Century. It is almost as ironic as Americans refusing to adopt The French Meter.

If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page and contribute. Also purchase his books about the metric system:

The first book is titled: Our Crumbling Invisible Infrastructure. It is a succinct set of essays  that explain why the absence of the metric system in the US is detrimental to our personal heath and our economy. These essays are separately available for free on my website,  but the book has them all in one place in print. The book may be purchased from Amazon here.


The second book is titled The Dimensions of the Cosmos. It takes the metric prefixes from yotta to Yocto and uses each metric prefix to describe a metric world. The book has a considerable number of color images to compliment the prose. It has been receiving good reviews. I think would be a great reference for US science teachers. It has a considerable number of scientific factoids and anecdotes that I believe would be of considerable educational use. It is available from Amazon here.


The third book is not of direct importance to metric education. It is called Death By A Thousand Cuts, A Secret History of the Metric System in The United States. This monograph explains how we have been unable to legally deal with weights and measures in the United States from George Washington, to our current day. This book is also available on Amazon here.

The Metric Philosophers

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By The Metric Maven

One Year Anniversary

This is the one year anniversary of The Metric Maven blog. One year ago on π day (2012-03-14) I published my first blog post. At about the same time, I contacted several prominent engineers, scientists and a celebrity chef, hoping for endorsement, or at least comment, on my proposal for a revival of the original Shafroth Bill  for the mandatory metrication of the US. I was looking for people who were well known as effective communicators in science and related fields, and who might have been expected to be sympathetic to metrication, or had made metric-favorable comments in their public venues. These included astrophysicist Neil deGrasse Tyson, fellow engineer Bill Nye, and proponent of science in cooking, Alton Brown of Good Eats, and others. I sent requests by e-mail and by USPS.

Now, I was not expecting a 100% response. In fact, I would have been astounded. But the actual response was just as astonishing: deafening silence. Perhaps it was a fool’s errand, but I wanted to try the experiment anyway.

One thing I believe I’ve learned over this year, is there seems to be three vertices to an impossible triangle of US metrication. At one vertex are anti-metric people,  at the second vertex are people who insist they are pro-metric, but never want a law, or compulsory plan, or public funding, or penalties for not using metric, or intervention of any kind. The third vertex consists of those, who, like myself, want metric legislation to press the issue, institute a quick metric changeover, and finally bring the  US into the modern era.

The anti-metric people probably will not change their minds about the issue unless something catastrophic occurs to them personally. Something like a misdosage of medicine is given to a loved one, or themselves, because of the lack of US metrication. Perhaps not even then.

The people who state they are pro-metric but are unwilling to see any legislation mandating metric, despite the clear mandate found in the US Constitution to do so, are the most curious to me. They cite “philosophical reasons” for their resistance to legislation. Every time I hear this from one of these “pro-metric” personages, I can only think of a scene from The Hitchhiker’s Guide to the Galaxy. Two philosophers show up to stop a computer named Deep Thought from computing the answer to Life The Universe and Everything. Here is the exchange:

“We’ll go on strike!” yelled Vroomfondel.

“That’s right!” agreed Majikthise. “You’ll have a national Philosopher’s strike on your hands!”

As Deep Thought wryly observes:  “Who would that inconvenience?”

These pro-metric “philosophical allies” seem to believe that history does not apply to the enlightened culture in which we live. We apparently have no need for laws against child labor, driving on the wrong side of the road, selling contaminated food, perhaps even murder? Philosophy will eventually vanquish it all. They might object that there is a line, and I’ve crossed it by indicating they would be for repealing laws against murder. I’ve had enough philosophy to identify a (slippery slope) continuum fallacy. How about we move that imaginary philosophical line so that mandatory metric legislation is included in what may be done, somewhere just before murder?

Being of a more empirical and practical bent myself, I see that we’ve had over 150 years of no laws, and also no metrication. That, as Vroomfondel the philosopher argued, “is a solid fact!” So, the plan from these metric advocates is that we continue without a plan and wait
for philosophy  to metricate the US. Could I humbly suggest, that perhaps after 150 years we should try something else? All other countries use metric, with the minor exception of the tiny two, Liberia and Myanmar, and have since the 1970s—you know, back in the 20th century.

The pro-metric philosophers however claim to have a plan, a plan they are sure will work. In their view it’s clearly a problem of product labeling. If we would just allow metric-only product labeling, then suddenly metric only labeled products would flood in from countries all over, business and commerce would suddenly move to all metric. So the problem is we have not “allowed” metric-only labeling in the US? This is asserted even as the same philosophers point out that we already have laws stating that metric is the “preferred” US measurement system. How could I think that we would need anything else beyond a statement to achieve metrication? Perhaps a nice letter, or thinking happy thoughts would be the catalyst that would finally bring metric to the US. When I hear these assertions, how can I not but think of the eloquent philosophers Vroomfondel and Majikthise?

So, how strictly is the US requirement of imperial units along with our “preferred” measurement system enforced? Well, in terms of enforcement, I think it’s probably somewhere just below jaywalking, but possibly above disposing of chewing gum on a public sidewalk.

These days I find more and more metric only labeling on store shelves. For instance, at a local meat market, I purchased French butter, which has proven very good for making cookies. Below is a photo of the dangerous contraband!

The butter lists only grams! and has graduations on the back in 25 gram increments! Worse yet!  It’s all in French! Indeed I had to ask the proprietors if it was butter to be certain. They looked at me as if I was daft and said: “It’s in the butter section, right? Yes, it’s butter.” As most unsalted butter is foil wrapped I could also assume that. Later I spied a sign in the window of my local convenience store advertising one liter bottles of soda, period, no imperial value listed! I observed convenience store non-imperial scofflaws again, during a recent road trip, where 0.5 liter bottled water was advertised on another convenience store window sign. This of course does not violate packaging laws, but does show no one really notices.

I’m then confronted with “Well, see, it’s working, we are right, you’ve made our point.”  Really?

In response to the conjecture by The Metric Philosophers, who believe that passing a law allowing metric only labeling, would bring about metrication in the US, I point out that the requirement for imperial labeling is ineffective, and not enforced. It has probably not been enforced the past, so passing legislation allowing metric only labeling is moot. That I find metric-only examples is seized upon by The Metric Philosophers, as proof metric is springing up all around us and they were right all along! Yet, I see no metrication occurring, and unfortunately observe numerous cases of metric backsliding. Perhaps it would be best if this  group of Metric Philosophers did go on strike.

There is an interesting twist to this “labeling issue”—Australia’s experience. You know, the English speaking country that did change to metric. The country which was poo-pooed in the 1975 US metric hearings. They might have some insight to offer. In his monograph Metrication in Australia, Kevin Wilks offers this assessment:

In hindsight, the early conversion of quantity statements on packaged goods and changes in package sizes had little impact on public education due largely to the universal existence of the supermarket method of marketing, in which packages were selected by the customer by visual size rather than by quantity name in either imperial or metric.

The supermarket proved to be one of the least effective educational tools. A longtime friend, who a couple of years back listened to a few of my conversations about metric, confessed to me not long ago: “I never really looked at the quantity labels in the supermarket until after you talked about them.”  I doubt she still looks at the labels to decide what size she will purchase. Metric Philosophers who believe that allowing metric only labeling will produce a philosophical tsunami which would directly lead the US to metric conversion, should consider looking into the actual experience of other countries before they make such a pronouncement. In the days before supermarkets, when people purchased commodities in bulk quantities, which were only meted out by someone like Sam Drucker,  going to the grocery store might have been more effective and instructive—because there was no pre-packaging..

I would like to believe that the “pro-metric,” anti-legislation cohort of Metric Philosophers is small, but that does not seem to be the case. It appears that pro-metric pro-legislation, pro-funding, pro-active, pro-plan persons like myself are a metrication minority. Like the impossible triangle shown above, none of the three vertices connect, at least not in this world. In my viewpoint, the pro-metric anti-legislation Metric Philosophers are more effective anti-metric apostles than are the passive anti-metric people. These Metric Philosophers seem willing to wait forever, generation after generation for their philosophy to bring metrication to the US. I myself, would like to see it happen during what’s left of my lifetime. In the end, it could be laws that bring metrication to the US, but they might be laws which are penned by the rest of the world, which finally force the issue. This possibility might be smaller than just waiting. Still, I’m sure the metric Vroomfondles and Majikthise in the US would still insist their philosophy would have worked—eventually.

Most of all what I learned during this year, is that there is probably no rational hope that this country will change to metric, perhaps for generations. Mother Jones magazine had an article in January of 1999 called Waits and Measures which invited its readers to “Meet the least powerful men in Washington.” The author was of course speaking of metric advocates. We are identified as the least powerful political lobby. If it’s possible, it appears we have become even less relevant over the last 13 years. The article profiles Jim McCraken who at that time ran the United States Metric Program. Today it appears that this position is held by Elizabeth Gentry. She won an award for her metrication work. The press release states:

• Elizabeth Gentry, NIST, Department of Commerce
Ms. Gentry was selected in recognition of her exceptional leadership as metric program coordinator with the National Institute of Standards and Technology, Department of Commerce. Ms. Gentry serves as the nation’s focal point for voluntary conversion to the metric system. She led an effort to persuade states to amend their laws and regulations to permit manufacturers and retailers to voluntarily use metric units on their packaging. At the same time she worked to ensure the laws of other countries to continue allowing current U.S. labeling while the transition occurs.

Indeed, metric in the US is voluntary, voluntary, voluntary. But, what measurement “system” must be ensured and preserved by our government? And backed by the same compulsive laws The Metric Philosophers claim to abhor? Why the farrago of imaginary units used in the US of course—certainly not metric. The Metric Philosophers never seem to object to these laws. Apparently this disused rusting junkyard of units is so important, and sacred, that all other countries must keep living with our Imperial/USC/ACSOWM/IS packaging—forever. Oh, I’m sorry—I mean during the “transition.” This would be the same open ended transition period approved by The Metric Philosophers, during which metrication will be achieved by the vigorous action of Philosophy. Metrication must not be held to any definite time constraint. I guess Tinkerbell would die otherwise. Ms. Gentry’s big metrication accomplishment, for which she received an award, is to try to allow metric only usage on packaging?—I think I’ve made myself clear on the potential effectiveness of that tactic.

I also learned this year that in every era, from John Kasson in the 19th Century until today, the US has such pressing problems, which are so important, that metric should never think itself worthy enough to be on the national agenda–ever! We just can’t fit it in. It’s not a serious issue Very Serious People contend. Congress has more important work to do investigating the use of steroids in sports, and re-naming public buildings.

I’ve written 40 essays, including this one, over the last year. You can imagine my embarrassment at not realizing that I should never have bothered. I should have just waited for The Metric Philosophers to make it all happen, with their efficient and effective inaction and reliance on the certainty of philosophy. I should have just waited at home until Home Depot, Lowes, ACE and TrueValue Hardware stores, suddenly sold millimeter metric only rulers and tape measures, in response to the intense philosophical pressure the Metric Philosopher’s ideas will certainly exert.

Laws, planning, organization and funding have not been tried in the US, but were instituted in Australia, and there, they did make a difference. These policies brought metric to Australia. All they did was alter their existing laws which required the use of imperial to now require metric. Different industries could decide how they would implement metric, but not whether they would. Perhaps we should give it a try here in the US. Perhaps we should adopt a new philosophy?

If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page and contribute. Also purchase his books about the metric system:

The first book is titled: Our Crumbling Invisible Infrastructure. It is a succinct set of essays  that explain why the absence of the metric system in the US is detrimental to our personal heath and our economy. These essays are separately available for free on my website,  but the book has them all in one place in print. The book may be purchased from Amazon here.


The second book is titled The Dimensions of the Cosmos. It takes the metric prefixes from yotta to Yocto and uses each metric prefix to describe a metric world. The book has a considerable number of color images to compliment the prose. It has been receiving good reviews. I think would be a great reference for US science teachers. It has a considerable number of scientific factoids and anecdotes that I believe would be of considerable educational use. It is available from Amazon here.


The third book is not of direct importance to metric education. It is called Death By A Thousand Cuts, A Secret History of the Metric System in The United States. This monograph explains how we have been unable to legally deal with weights and measures in the United States from George Washington, to our current day. This book is also available on Amazon here.