A Brief History of the Metric System

I was quite surprised at the substantial cost of A Brief History of the Metric System, and when it arrived, that it was only about 6 mm thick. I was unprepared for its fealty to contemporary research on the origins of the metric system. I can say, without equivocation that the discussion of the metric system—though brief (as the title states) is the most complete I have seen. Carmen J. Giunta states early in Chapter 1:

The metric system did not “evolve” from the customary weights and measures in use in late eighteenth-century France, but neither did it spring fully formed from the enlightened minds of that nation’s savants.

He hints that the history as it has been portrayed in the past has been incorrectly stated. He immediately begins to discuss John Wilkins and Christopher Wren’s musing on what the basis of a universal measurement system might consist. He mentions details of Wilkins investigation of which I was previously unaware. Wilkins discussed using the Earth as a basis for measurement, but dismissed it as impractical. Giunta traces the idea of using a seconds pendulum as a basis for length back far earlier than Wilkins, and how Jean Picard (1620-1682) suggested in 1671 that the period of the seconds pendulum might vary with latitude. He goes on to describe how there was an anemic attempt in Britain to address weights and measures with a seconds pendulum, around the time the metric system was under discussion in France, by John Riggs Miller (c. 1744-1798) which fizzled out.

Giunta’s discussion of measurement contemplation and (non adoption) in the United States contains a number of interesting historical nuggets I had not previously encountered.

For such a short monograph, Giunta has a more nuanced discussion of the creation of the metric system in France than I have encountered with other authors. He states:

Other committees constituted in 1791 included Borda and Cassini to measure the seconds pendulum;……”

Other authors generally do not discuss the elaborate seconds pendulum designed and measured by the French scientists who developed the metric system.

His discussion of the development of modern SI states:

When the SI was launched, the kilogram was the base unit of mass, defined by the international prototype kilogram of 1889. A proposal was made to change the name of kilogram since it was undesirable for one of the base units to have a prefix, but the name survived.

Long-time readers know that the use of a lower case k for kg, km, kN, etc., has always been a pet peeve of mine. Other magnifying prefixes are capitalized, Mg, Tg, GHz, why not Kg or Km?

There have been a number of proposals for base units, but this was new to me:

In Germany, the preferred set of mechanical base units was the millimeter, milligram, and second; call it mms.

In Chapter 6, his final chapter, he discusses The Metric System and the United States. He gives a good summary, but then, in my reading of history, and of John Quincy Adams’ report on measures Giunta has an incorrect interpretation of the concluding paragraph of that report. He states:

Adams was effusive in his praise of the metric system and of the basic science that came out of its invention.

Adams’ concluding statement was actually veiled snark, and certainly not a pro-metric statement given the context of his report. Adams was an Anglophile with an English wife. It becomes clear in his report that Adams is NOT pro-metric, and definitely against the new system. Others in history who read the report in the late 19th and early 20th century commented that it was anti-metric, and held back metrication in the US. They even point out that his “perfect” English system, only 3 years after his report, was reformed and replaced in the UK by the British Imperial System. We in the US still use earlier British medieval units of measure. My discussion of JQA’s report may be found here.

Giunta offers a graphic from NIST showing a metaphor of an iceberg that almost all of industry uses metric. I’ve never seen a study that can even demonstrate we are even 50% metric in the US, let alone 90%. My experience as a consulting engineer is that I have not encountered a single medium sized corporation that uses metric in the US. Certainly not aerospace, which is definitely a large corporation. If the book Flying Blind is any guide, aerospace will remain non-metric indefinitely.

Giunta finally concludes by offering his view of Why is the US Still not Predominantly Metric? He concludes, like many others, that the US government has never mandated
metric for use in our economy. He is correct that it is very unlikely the US will become metric anytime soon. Perhaps in 1000 years?


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.

On the Level

When I was a very young boy in my Midwestern small town, an older boy a couple of doors down, named David, was always showing me new and interesting tools. The first was a round magnifying glass. He concentrated sunlight and burned a hole through a piece of paper. I thought is was amazing. The second item I recall was a really tiny spirit level. I spent a lot of time checking how level the kitchen table was versus the kitchen cabinet, and other surfaces. I seemed so neat, and the color of the fluid was mesmerizing. I did not realize it had been specifically chosen:

The color of a spirit level vial is traditionally a range of yellow-green because, quite simply, this is the central range of color most visible to the human eye in all lighting conditions. On either side of the visible light spectrum is purple-blue on one side moving toward non-visible ultraviolet light and orange-red on the other moving toward the non-visible infrared light.

It seemed so simple, just center the bubble between the lines, and you knew it was level. As a boy I did not realize that a measurement like this only guaranteed something was level just along the line of the level. Levels have a 0 and 90 degree set of vials (tube that has the fluid and bubble with graduations). If you place this on a surface, and the bubbles in both vials are centered, the surface is level. This is useful for leveling RVs.

I vaguely recall either my father or grandfather (who had a huge level for his carpentry work) showing me how to check a level. You would just reverse it end-to-end and check to see if the bubble reading was the same.

Recently, my significant other wanted to adjust a number of picture frames that had become crooked. She asked me to eyeball them, which works, but I suggested just using my small bullet spirit level. Suddenly she was of the opinion this device should be in her care, rather than in my lab. I balked at the idea. My level has a strong magnet to hold it to metal surfaces. I ordered a couple of smaller, and somewhat inexpensive levels made from acrylic plastic. When they arrived, I was taken aback that the scale on them was in inches, but the level sensitivity is in millimeters per meter.

Spirit level for leveling picture frames

The sensitivity of a level tells you how sensitive the bubble in the vials is to a change from level. The bubble on a level with 1.0 mm/m sensitivity which is tilted, will move much more than a level with only 10.0 mm/m of sensitivity. Hultafors has a nice video demonstrating the difference using levels with these two sensitivities. Another way to look at this is that if you have a bubble centered, and the sensitivity is 1.0 mm/m then a line extended to one meter will be within +/- 1 mm of level. Of course in ‘merica, sensitivity is in inches per foot, because why use one compatible set of units when two are available.

Out of curiosity, I began to see if any levels are available with millimeter-only metric scales. In many cases levels don’t have a scale on them as they are used for leveling, and not linear measuring. I set my browser for Australia and searched for levels with millimeter rulers/scales. All I could find were levels whose total length is labeled in millimeters, but the scale on them is centimeters. Over and over I found this:

In some cases I found them labeled with inches and millimeters for total length, and inches and centimeter scales for linear measurement. The only device I found with a level and millimeters is for use in finding angles:

And it has an inch scale on it! What I did find, is that if I wanted to have a level with millimeters, the Japanese have this solution:

Quoting Monty Python, “it’s really not much of a cheese shop is it?” There was another type of converter offered, but it was really not any better. Why not just sell levels with millimeters on them?

If there is to be a scale that’s on the level, let it be millimeters.


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.