By The Metric Maven

The first planet discovered using a telescope was Uranus. There have been many sophomoric jokes made at the expense of this planet’s name—but I would never argue that its name be changed. The name Uranus was not in fact, the original name proposed for this celestial body. Its discoverer, William Herschel (1738-1822), named it George. The official Latin euphemism for this title was Georgium Sidus, or George’s Star for King George III. This might strike a contemporary person as the scientific equivalent of A Boy Named Sue. A planet named after a person?—that’s all messed up. The names had been chosen, up to that point, in a manner which eschewed modern, or even real persons, by using the names of classical gods. George is immediately seen as not comporting with this nomenclature.

What strikes me is that the metric system also began this way by using names which were as decanted from humans as possible. The meter, the liter, the gram, and such were all words designed to be as neutral as possible. This began to fork when derived units appeared. Both the cgs and mks systems began to use the names of famous scientists for the names of derived units, but not always. The cgs system used erg (which derives from a Greek word meaning “work”). I like the name erg, it is derived from a word descriptive of what it is trying to represent, while SI adopted the name joule after the English physicist James Prescott Joule (1818-1889) who did pioneering work on energy.

In my view, naming a measurement unit after a person opened a Pandora’s box, much like allowing a newly discovered planet to be named George would have been in astronomy. Eponymous measurement units interjected a potential political, nationalistic and geocentric aspect to the metric system which in my view has not served it well. Clearly, the choices could easily become (and in my view have been) scientific popularity contests, where the idea of measurement unit names, which compactly describe units, was abandoned. In its place was the idea of further “honoring” persons, who are already immortalized in the history of engineering and science, by using the names of measurement units. This choice would immediately lead to political pressure, which could indirectly lead to unit proliferation. After all, we would want to include everyone—right? It becomes Celsius vs Fahrenheit vs Kelvin and the question of who “objectively” did more to further that unit’s development (or should it be the first who did work on it?). Is it Gauss (cgs) or Tesla (SI)? that contributed the most to (electro)magnetism—I will keep to myself which of these two clearly did more in my view. I will however comment that people who appear of paramount importance to their contemporary history, when judged years later are sometimes no longer seen as towering, or even very important, when closely examined in hindsight. It would be best not to create eponymous measurement units in the first place.

One person I have in mind which exemplifies this is William Henry Preece (1834-1913). Preece rose through the ranks of industry with very little education, and had almost no theoretical insight into the nature of electricity. He saw electricity as similar to water flowing through a pipe. He would never master AC circuit theory, let alone have any understanding of Maxwell’s equations. Even when it was clear that his view of electricity was wrong, he steadfastly refused to budge. He dismissed theory with disdain. He also had all the political connections to make him a formidable adversary—independent of his meager knowledge.[1]

Preece reviled Oliver Heaviside (1850-1925) who was an amazing autodidact. Heaviside would recast Maxwell’s equations into the vector form which is used by engineers and scientists to this day. Heaviside coined the terms inductance, and impedance, admittance and conductance, permeability and reluctance. These are all used in modern electrical engineering. He invented transmission line theory. Despite Heaviside’s towering contributions to electrical engineering, it was Preece who had a unit named for him. A preece is 1013 ohm-meters. I’ve never actually seen this unit used, but he managed to get one named for him non-the-less. It is a perfect example of why measurement units should not be named after people.

Another issue is that a choice of words with the least number of syllables would probably be of utility. Why is it ok to take the name Volta and reduce it to volt, but not take Ampere and change it to amp? (A professor once chastised a student in a class for this by asking if he worked at a garage?—the unit is an ampere!). Why doesn’t George Westinghouse get his own electrical unit?—too many syllables?

Recently I viewed a clip from a British game show which asked a panel “what is the metric unit for weight.” There was much fumbling, and the presenter had to finally tell them it was a newton. Get it?—Isaac Newton is English—and the British contestants didn’t know the measurement unit for weight was named after the great English scientist. That a measurement unit is coupled with a nationality is almost anthropomorphizing it. Until 1948 temperature could be centigrade, after that it became the eponymous Celsius. In another essay I point out I would have it reintroduced as milligrade. Taking the name of a measurement unit, which has some manner of neutrality, and then re-naming it after Celsius is a disservice to metrology, engineering and science.

One metric measurement unit name that appears to suffer from its lack of a descriptive name is the pascal. When a person in the US hears PSI its immediately translated to pounds per square inch. Every American thinks they know what that means. The very name seems to explain itself. 1000 PSI—wow!—that’s a lot! One PSI—not so much. Because we have not embraced the metric system, and better educated ourselves, most Americans think a kilogram is a force, and a pound could be a mass. So if you tell them something has a pressure of 6895 Pascals—wow!—that sounds big!—but it’s 1 PSI or 6.895 kilopascals. A US citizen would be confused as as to where the kilograms had gone and how they had become kilopascals. When I recently explained to a technician working on pressure lines, which he was connecting to a “foreign” machine, that a pascal is a newton per square meter—there was an immediate recognition on his face. Should the pascal ever have been defined? Perhaps it could have been left as newtons/square meter?—NSM? In the cgs system there is the gal for a unit of acceleration, but in SI it’s meters/second squared. The gal is said to be short for galileo, but should it ever have been named and defined? People can envision what a meter per second per second might be, and hiding it inside of an eponym disperses clarity. In the case of a unit like a volt, its base units are: m2·kg·s-3·A-1 which I believe very, very few people can visualize, and a name of some type makes sense. It’s too bad it’s an eponym.

There are frivolous units like the barn, which should long ago have been abandoned, but like the continued use of cgs in the US, people who are used to our polytheistic units see no problem just adding more ways to redundantly describe the world. (FYI cgs and SI are incompatible systems)

In 19th century attacks on the metric system, one will often see the complaint that the units have too many syllables. Most of the examples are cherry-picked, but I believe it should have been a consideration in naming metric units. In cgs the force unit is a dyne (single syllable) and in SI it is a newton (two-syllables). The descriptions should be as simple as possible and no simpler. The names of measurement units should not be based on “honoring” already celebrated scientists, nor uncelebrated ones. The angstrom is a good example of an eponymous unit which only kludges up the metric system and makes it less straightforward. Thankfully nanometers are commonly used these days to describe wavelengths of light. But will those who are from Sweden feel slighted?—and continue to use it in a patriotic protest? Nanometer tells you directly in words what the value of the unit magnitude is in relation to its base, the Angstrom does not. It should have never been coined for a scientific unit.

I expect the probability is small that the metric unit naming issues I’ve related will ever be addressed by international standards committees. In fact it is likely far, far more remote than that of the US becoming a metric nation like Australia. But that does not mean I will not write about it, and implore that this not be done in the future. Spacecraft will continue to be launched. Continue to use spacecraft names to honor scientists—not measurement units. The first rule of getting out of holes is that when you’re stuck in one, you should first stop digging. Add no more eponymous units.

[1] Oliver Heaviside: Sage in Solitude Paul J. Nahin, IEEE Press 1988

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