“A myria-myrio mystery—
Some prefixes, lost now to history:
These factors, past-metric,
Deemed over-eclectic
In measured decision’s delivery.”
The 29 April 2024 Twitter limerick summarized what had been a newfound discovery for me last spring– that the list of metric prefixes commonly used in science used to be longer. As ever, I find it frustrating that time constraints and coverage expectations preclude the discussion of such points in coursework, but it is a good opportunity to explore the story here.
“A myria-myrio mystery— /
Some prefixes, lost now to history…”
The metric prefixes are enormously useful aspects of scientific communication, allow us to easily communicate measurements expressed in the International System (SI units) on a variety of scales. Distances between towns on a map are generally expressed in kilometers (km), which means 103 meters; the metric prefix kilo stands in for 103, or 1000. Atomic sizes are expressed in picometers (pm), which means 10-12 meters; the metric prefix pico stands in for 10-12, so showing that order of magnitude would otherwise, inconveniently, require eleven zeroes before the 1.
The prefix myrio, also expressed myria, indicated the order of 10,000 (104). While it was used with the SI units for several centuries, it was eliminated from usage at the General Conference on Weights and Measures in 1960, where the SI units were adopted internationally. Such prefixes are “lost now to history,” as the accepted metric prefixes now jump from kilo (103) to mega (106).
“These factors, past-metric, /
Deemed over-eclectic /
In measured decision’s delivery.”
For myrio specifically, the reason for its removal seems to have been aspirational clarity in metric abbreviations. The prefix myrio/myria had historically been abbreviated as my. As the metric prefixes were standardized, scientists moved towards abbreviating all the metric prefixes with single letters for simplicity (as noted above, kilometers are km, and picometers are pm). The letter M is already used in both its capital (M for mega, or 106) and lower-case (m for milli, or 10-3) forms, so that myrio and myria would be “over-eclectic.”
The discussion at the pertinent metrology conference could presumably be characterized as a “measured decision” in a few ways.
Chemphasis 