Length Mass Time Temperature

The four fundamental measurements most commonly used by humans are:

circa 1300

The first official definitions of inch, foot and yard are established in England.

1585Simon Stevin (born in Belgium in 1548) printed a book urging the adoption of a decimal system for coins, measures and weights.

1670Gabriel Mouton (born in France in 1618) published a book describing a metric system of measurement.

1790

The French Academy of Science defines the meter as one ten-millionth of the distance from Earth’s pole to the equator.

𝟏𝟏𝟎𝟎𝟎𝟎𝟎𝟎𝟎

1792The US Mint produced the world’s first decimal currency, the dollar, which contained 100 cents.

1795France became the first country to officially adopt the metric system.

1866Congress passes a law recognizing, but not requiring, the metric system.

1875The Treaty of the Meter was signed in Paris, France by 17 nations, including the USA.

1889France sent to the USA prototypes of the meter and the kilogram to be used as standard measurements.

1893By federal law, the USA changed fundamental standards of length and mass to metric standards.

1960The General Conference on Weights and Measures adopted the name “System International” (“SI”) for the metric system and established rules for prefixes and the base units.

1967The SI unit of time, the second, is changed to an atomic constant, instead of a reference to the Earth’s rotation.

1983The SI unit of length, the meter, is changed to refer to the speed of light.

1994Congress amends the Fair Packaging and Labeling Act to require metric units on most consumer products.

HOMEWORK ASSIGNMENT !

2005

The SI unit of temperature, the Celsius degree, is changed to refer to an atomic constant.

2014

The SI unit of mass, the gram, is expected to be changed to refer to an atomic constant.

(Short) History of MeasurementHuman-centered (> 6,000 years)Earth-centered (~ 200 years)Universe-centered

time since 1967length since 1983temperature since 2005mass change pending