Category Archives: Metric Reform

Evanescent Measurement Policy

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By The Metric Maven

Bulldog Edition

One day I was visiting a production plant which creates and molds materials for electronic components. I noted they were measuring the length of the component in barleycorn inches with a few zeros at the front of the decimal. The data was being entered by hand onto a paper table held with a clipboard. I indicated that it would be wiser to measure in millimeters so the data didn’t contain so many leading zeros and provide such an easy opportunity for error—and there would be less redundant digits to write down. They next measured the mass of the object in grams with a scale that went way way down into the microgram range. It also had a large number of leading zeros to the right of the decimal point.

After they had obtained the mass (in grams) and volume (using inches) they computed the density or mass/volume. I was told it was expressed in grams per cubic centimeter. I did have an attack of the vapors realizing they were using pigfish measurement, and then converting to metric, and worst of all used cubic centimeters. The metric system has a nice unit for volume called the liter. A cubic centimeter may be a volume dimensionally, but it is a milliliter which is an appropriate volume unit in my view, and identical to a cubic centimeter.  The cc is a part of the cgs system, and has long been abandoned.

Along the way I was shown the dielectric material in granular form before it undergoes processing for later fabrication into electronic parts. The materials chemist was pleased to tell me that they were all created to be about 100 microns in diameter. I cringed slightly, and then said “you mean micrometers?  Micron is a term from the 19th century and is not expressive.” Little was said after my comment and we moved on.

During a discussion about part fabrication difficulties, mils (thousandths of an inch) were bandied about constantly. I finally asked about the surface roughness of the material. I had determined it could contribute to the problems they were having. I was given a value in microinches. A metric prefix with Ye Olde English?—sigh. I could only reply with “I have no idea what size that is.”  I was then quoted a value in microns. Again with the microns? I wanted to do a face-palm, but refrained.

I have been on many tours of engineering and production facilities. It was only when I was at this particular establishment that I realized, I’ve never toured ANY company that has a measurement policy or measurement coordinator. It is not discussed, contemplated, seen as a concern—nada. When I bring up metric measurements, it is as if my statements and questions vanish into a black hole of indifference.

A week or so later another engineering client sent me a drawing which has a part made from a similar ceramic material. The dimensions on the drawing were all in inches, but in the notes, the metalization thickness on the part was called out in micrometers. The second note described the density of the part in grams per cubic centimeter (g/cc). I just stared at the drawing, and thought about my recent visit. Inches, micrometers, and the cgs unit g/cc all on the same drawing? Three different measurement types on one drawing. Why does this strike only me as bad engineering practice?

Density is mass per unit of volume. The density value on the drawing was 3.73 g/cc +/- 0.1%. In SI the milliliter (mL) would be an appropriate volume which would be 3.73 g/mL +/- 0.1%.  The cgs/SI/Ye Olde English mixing of units has become so accepted in the US that it goes without notice apparently. As I said, thus far I’ve never seen a company that has a “Measurement Coordinator.”  This would be a person who would help create a measurement policy and apply Naughtin’s Laws as well as the rule of thousands. That person would examine, simplify and coordinate measurements to maximize the understanding of data presentation and reduce possible mistakes—and implement the metric system. It never occurs to business management that measurement coordination could be a cost or efficiency issue.

I’ve always been tasked with design work, and never anything which would involve setting measurement policy. Pat Naughtin was the first to discuss the fact that NASA’s measurement policy is “change to metric, if you want to, use centimeters and/or millimeters, if you want to.” In other words NASA simply didn’t see measurement policy as a problem which is in need of any coordination or effort. This means they don’t see it as a problem at all, and so they do not have a measurement policy. Unfortunately the current former head of NIST also has a “do your own thing” measurement policy.

In the back of my mind I wondered what the reaction of one of my clients might be if I brought up the possibility of a measurement coordinator. I had concerns about it, and the next time I was on the phone with Sven, I asked him what he thought the reaction might be from management and a group of engineers.

Sven: “They would not see any need for it, and they would look at you as if you were wearing a gunny-sack with a belt and sandals, had a long beard, and were holding a sign which read REPENT!”

MM: “I was afraid you would say that.”

Every engineer I know believes they understand measurement units and measurement. There is no need for a policy, we “learned” it all in college. Some co-workers have indicated to me that metrology is what people do who really don’t have any engineering talent. You can imagine how my psyche greeted that notion. I’ve met way too many “engineers” who embrace measurement methods which are ad hoc and unsound. They chase down blind alleys of impromptu measurement and waste time. But as long as a product “gets out the door” and appears to work—there is no problem here—move along.

Isaac Asimov in an essay called Forget it! pointed out that often measurement units that should have been abandoned long ago, continue to be used. The units are also only imperfectly forgotten, which leads to an even more chaotic usage. The cgs system was abandoned many years ago, but the inertia of unrestricted usage propels them into the future.

I spoke with a medical researcher at a block party last summer, and mentioned metric. He proudly stated he uses metric in his work and cited the cubic centimeter. I pointed out that the cc was part of centimeter-gram-second system, and the cgs system is not compatible with SI. He should be using milliliters. He looked at me as if I was daft, and going out of my way trying to be annoying.

The technical drawings I received with cc’s on them, show an incomplete ability to forget cgs, as do the density measurements performed by another client. Recall they first started in inches with a long number of zeros past the decimal point, then converted the inches to cc’s, and then finally computed grams/cc for a density. The inch is Ye Olde English, the gram is SI, and the cc is cgs. Both the inch and cc should be forgotten and eschewed; but the 10th, 14th and 19th  centuries live on in the US, never forgotten or allowed to be. They are the products of the “unexamined engineering life.”

I wholeheartedly agree with Pat Naughtin’s call for measurement coordinators and measurement policies in industry. As he himself pointed out, often questions of measurement are considered so minor, that scales and other measurement instruments are chosen and ordered by secretaries or interns. To show they are giving the company the most value, they order dual or multiple scale measurement devices. This perpetuates the farrago of units in use.

NASA demonstrated itself to be immune to the notion of measurement coordination even after the Mars Climate Orbiter disaster. The much less well-known DART “mishap” even appears to have been obfuscated with a mantle of junk prose. It was more important for NASA to deny there is a need for measurement coordination, than to address the problem. I really have no idea what it might take for the technical community, educators and the public to realize that measurements are the real currency upon which our modern technical society operates, and there is a need to coordinate and simplify them. I can only hope for the US metric coma to finally recede, the country to wake up, and then finally address the problem.

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 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.

A Matter of Scale

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By The Metric Maven

Years ago, my friend Ty introduced me to the world of magical illusion. It was during this time I realized that seeing may be believing, but believing what you see is not guaranteed to be reality. For instance, one evening I attended the Indiana State Fair. I had played basketball in high school and took immediate interest in the free throw area. I had seen many of these before at carnivals, and they all had some modification of the basketball basket to make it much harder to make a free throw. The width (diameter) of a regulation basketball hoop is large enough for two basketballs to pass through it at the same time. Often, this diameter will be reduced, or a second rim will be installed to reduce the probability one will make a free throw. These modifications are usually very obvious.

That evening, I held up the regulation basketball in front of me, and used it to judge the width of the basketball goal.  It looked like two basketballs would fit. I was assured by the person manning the booth that the goal was regulation width. The other variable was the distance to the basket. I could not see the side view of the basket as there were canvas drapes on either side. I paced off the distance as best as I could and it seemed approximately the right distance.

I tried to shoot and it was short, I shot again and it was still way short. On my third and last try the basketball rattled out in a  very strange manner. I knew something was wrong, but didn’t know what. I walked around and studied the situation. Finally I was able to just peek between the seams in the canvas. The basketball goal was an oval!  From the free throw line, its width appeared to be regulation, but a basketball would barely fit through the goal from front to back. It would be almost impossible to ever make a shot. Another person realized what was happening, became angry, and started yelling at the operator. I began laughing, and walked up to him and said “learning how this worked is worth $5.00.” Before I had figured out the illusion, I was sure something was confusing my perception, because for a few years my friend Ty and myself performed magical illusions at parties we attended and elsewhere. I had learned not to trust my perception—especially at a carnival or fair.

I recall the first time I saw an engineering photograph with a ruler in the foreground. I thought it was genius. The scale is right there to provide an accurate and exact scale for the photograph. I believed (and still do) that design photographs should have scales in them.

Assuming a car is about 15 feet long isn’t the woman closer to 100-150 ft tall?

I ran across the above photograph, which has a person with the Eiffel Tower, when I was researching the Eiffel Tower for another essay. The person appears to tower over the tower. One immediately realizes that the photograph probably shows a person that is close to the camera, with the landmark in the distance, which makes him look larger than the tower. The problem is not because of the absence of an official scale, but that two contradictory ones, one which is approximate, and one which is rather accurate and known, compete for your perception. This is more formally known as forced perspective. The Eiffel Tower is often known elsewhere in the world as the 300 meter tower. The man standing next to it is probably about 1500 millimeters tall. Is the tower a miniature?, along with the background?—or is the tower far away?—or is the man actually a giant! We cannot be completely certain. Well, we can be fairly certain that a person who is over 300 meters tall would probably be structurally  and biologically unsound, and in need a serious amount of food each day, so we can scratch the giant alternative. The addition of a ruler type scale in photographs can help, but it can only do so much.

Often engineering photographs will have coins or other familiar objects to act as approximate scale references. I’ve seen South African coins used, as well as Euros, and US currency. I have no immediate idea of the size of the non-US coins. That’s why I’ve always been a fan of a nice photo documentation ruler. I see them in archeological photographs, paleontology photographs and elsewhere in engineering and science. The targets and alternating stripes on the rulers used in engineering and scientific photographs have always held an unexpected fascination for me. What I’ve found somewhat surprising, is the apparent lack of standardization of photographic documentation scales. What first made me think about this was when I recently viewed a photograph from a collection by the 19th Century photographer Timothy O’Sullivan. The photograph of interest is reproduced below:

An earlier visitor: Nearly 150 years ago, photographer O’Sullivan came across this evidence of a visitor to the West that preceded his own expedition by another 150 years – A Spanish inscription from 1726. This close-up view of the inscription carved in the sandstone at Inscription Rock (El Morro National Monument), New Mexico reads, in English: “By this place passed Ensign Don Joseph de Payba Basconzelos, in the year in which he held the Council of the Kingdom at his expense, on the 18th of February, in the year 1726” (click on image to enlarge)

When I first looked at the scale in the photo, I thought “it has to be inches,” but the numbers and graduations seemed just too closely spaced, they looked somewhat like centimeters. The photograph was taken in 1875, so it’s not impossible it could be metric, but in all likelihood it is in inches, but how to know?  Sven noted that the length is 36—somethings, which could well be a yard. It is also possible that in the early days of metric a 36 cm rule might have made sense to people of that time. The rule is only graduated in even numbers, and with 2.54 cm to an inch it gives one pause—no that doesn’t make sense. The handwriting could be of any size and the form of the letters used is not consistent. The plant in the foreground is unfamiliar and not useful for scale. Clearly the photographer knew the units on the scale, but posterity is less certain. If the scale is 36 inches, then the width of the yardstick is about 2.31 inches or 58.7 mm, which seems reasonable. If the scale simply had inches written on it, or a yard, or both, that would help.

When I began doing my own engineering consulting, I decided I wanted to use photo documentation rulers (PDR) when taking photos of my designs and other devices. It caused me to observe PDR’s in a more careful manner than I previously had. In a recent PBS Nova I noted this PDR:

Human finger ring found by archeologists made of jet

In this case, the labeling actually causes some confusion. Are the alternating stripes each 5 cm in length?—or is the entire scale 5 cm and each stripe 1 cm? As this is a ring, one can be fairly sure it is the latter, as a 20 mm inner diameter makes sense. The idea of putting the photographic documentation ruler there in the first place is to remove the need for context. I decided the scale of the PDR based on knowledge of the object. Clearly this is not a good scale label. It is very common for metric PDRs to have 1 cm length stripes. Unfortunately many PDRs which are for sale have centimeter numbering, but use mm for an alphabetical designation. This is the same problem one finds with US rulers.

Centimeter numerical graduations with mm label

The inch version has no alphabetical designation. One would have to infer its units by the context of the subdivisions, as they appear fractional:

The inch PDR has no inch label. It assumes you know the units, possibly from the way the divisions are implemented.

Rather than accepting  the ways I’ve generally seen PDRs designed, I very much like the idea of using 10 mm length stripes on PDRs. I would also like the numerical designations to match so that the scale has divisions which are 5, 10, 15 and so on. A label which states mm would be adequate to make certain one understands the numbers and labels are consistent. A further advantage is that one would not confuse a centimeter scale with an inch version which one would also expect to have 1, 2, 3 and so on as numerical designations.  Below is a scale used by the Allegany County Coroner’s Office which clearly shows millimeters, but lacks alternating black and white stripes. Clearly one can tell it is a mm only scale.

In my search I found a few—very few options for the type of photo documentation rulers I’ve described. One I commonly use in my work is also used as the mast head graphic for this blog. I also use an L shaped PDR which was purchased from SIRCHIE. Forensics Source is another vendor that has some mm only PDRs.

Recently archaeologists in Denmark uncovered footprints on a Danish island which are over 5000 years old. This photograph appeared with the article:

o-HUMAN-FOOTPRINT-570

The large scales I own have orange and white alternating stripes, which are each one hundred millimeters (a decimeter) in length. The ten millimeter stripes used for the ring example previously discussed were confusing even though it had 5 cm written on the scale. In this case we see a handwritten 40 on the scale. Once again we end up estimating the length of the “documentation scale” and guess its unit by noting that an adult male human foot is around 250-300 mm, but could it be a woman’s foot, a child’s foot?–a hobbit’s foot?

When I watch television programs such as Forensic Files, I see metric, millimeter, centimeter, dual-scale, and inches only PDRs, but one one night I saw this:

It appears to be an adhesive scale with inches in an outlined typeface, and boldface feet. You can see it goes from 1 to 11 (like Spinal Tap) and then a bold 1 appears meaning one foot. The second one which follows is a new inch after the foot designation. Only in the United States would one see a scale with feet and inches without any alphabetical markings to clarify the matter. This is forensic evidence?—I expect better.

In my view, long ago US law enforcement, coroners and others should have standardized. It is my contention that the best standard would be to use millimeter only scales, with 10 mm calibration stripes, and numerical millimeter designations. The stripe lengths would still be consistent with the old cm versions, but the numerical designations would not be confused for centimeters or inches. The exchange of evidence between US jurisdictions and foreign countries would never entail any conversions if this was done, be it shoe prints, tire prints, or other evidence. Complexity only provides opportunities for error. This is yet again another symptom of the fact we have never had a government coordinated mandatory metric switch-over in the United States. This measurement autopsy is not pretty, but unlike a biological one, we can resurrect and bring the body of measurements in the US to complete health, but this cannot be done in isolation. Without government intervention, and business cooperation, it may never happen, much to our detriment.

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 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.