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NEWS | June 14, 2021

The science of measurement

By Michelle Gordon U.S. Army Aviation and Missile Command

Measurement impacts everyone around the globe, which is why the scientific community comes together each May to celebrate the standardization of measurement on World Metrology Day.

Time of day, miles per gallon, temperature, etc. — all of these items can be measured, but it was not until May 20, 1875, that multiple countries gathered at the first Metre Convention in Paris, France to establish standards of measurement.

During the first convention, the 17 participating countries were only concerned about standardizing mass and length. However, over the years, participation in the conventions grew, as did the number of standardized measurement units.

There are now seven basic units of measurement agreed upon internationally — length, time, amount of substance, electric current, temperature, luminous intensity, and mass.

For employees of the U.S. Army Test, Measurement, and Diagnostic Equipment Activity, located on Redstone Arsenal, Alabama, measurement is at the cornerstone of everything they do in their work to ensure Army weapons systems and devices are calibrated. Although the two terms are not synonymous, calibration involves several different units of measurement.

“Measurement helps us define units back to a reference standard,” said Robert Branin, USATA deputy director for management and operations. “Whereas calibration is the practice of comparing reliable and traceable sources of measurement against a device that has questionable accuracy.”

Branin described the use and importance of both measurement and calibration with the example of ensuring an aircraft altimeter is properly calibrated.

“The altimeter tells you how high you are in an aircraft,” he said. “That provides information in a measured quantity that is important to the pilot. In order to calibrate that altimeter, we compare it against a measuring device with a known accuracy. If we fail to periodically check that altimeter against a measured standard, then it introduces risk that could certainly lead to a catastrophe.”

Branin said USATA celebrates World Metrology Day each year, often with an organizational day with games focused on metrology trivia. This year, due to COVID-19 restrictions, the small celebration will be limited.

The theme of this year’s celebration is Measurement for Health.

Aside from the obvious COVID-19 connection, where metrology plays a role in vaccine creation and efficacy, as well as the size of virus molecules, Branin said metrology is found throughout each health care encounter, such as blood pressure measurement, temperature, and lab work. Although he did chuckle when it came to measuring body weight.

“Most of us have a scale in our bathroom at home,” he said. “Then when we get to the doctor’s office and it reads something a little different, it’s only then that we might question the accuracy and calibration of those scales.”

For more information about World Metrology Day, visit