Noah’s Ark

Make thee an ark of gopher wood; roomsshalt thou make in the ark; and shall pitchit within and without with pitch.

And this is the fashion which thou shaltmake it of; the length of the ark shall bethree hundred, the breadth of it fifty, andthe height of it thirty.

Genesis 6: 14-15

Unit of Length Used in Genesis

The length of your forearm.Cubit

First recorded unit of length.

Egyptian Cubit RuleLiverpool Museum

Leviticus

Ye shall do no unrighteousness in judgment, in meteyard, in weight, or in measure.Just balances, just weights, a just ephah, and just hin, shall ye have.

Unit Stnds Established in the Magna Carta

Agreed to by King John of EnglandRunnymede, 1215

Clause 35

There shall be one measure of wine throughout our whole realm,and one measure of ale and one measure of corn -- namely, the London quart, and one width of dyed and russet and hauberk cloths-- namely, two ells below the selvage.

(a textile’s selvage)

London Quart

Ell = a yard and a quarter

Unit Stnds Established in the US Constitution

Section 8… fix the Standard of Weights and Measures; …

Mars Climate OrbiterThe Mars Climate Orbiter was intended to enter orbitat an altitude of 140.5–150 km (460,000-500,000 ft.)above Mars. However, a navigation error caused the spacecraft to reach as low as 57 km (190,000 ft.). The spacecraft was destroyed by atmospheric stressesand friction at this low altitude. The navigation errorarose because the contractors for craft's thrusters didnot use SI units to express their performance.

The thrusters on the spacecraft, which were intendedto control its rate of rotation, were controlled by acomputer that underestimated the effect of thethrusters by a factor of 4.45. This is the ratio betweena pound force (the standard unit of force in theimperial system) and a newton (the standard unit inthe metric system). The software was working inpounds force, while the spacecraft expected figuresin newtons; 1 pound force equals approximately4.45 newtons.

Wikipedia

Ancien Regime Weights and Measures

800 Unit Names

250,000 Different Units

Town Hall of Laon, France

“T” for the Size of Barrels

Ell for Cloth

Gauge for Bricks

Gauge for Roof Tiles

Origin of the Metric System1790French National Assembly requests the French Academy of Sciences to

…deduce an invariable standard for all the measures and all the weights.

Charles de Talleyrand-PérigordIn place of a measure derived from history or the fiat of kings,he asked that the legislature derive its fundamental measurefrom nature, the common heritage of all mankind. Only a measurederived from nature, he declared, could be eternal because onlysuch a standard could be reconstructed should its man-madeembodiment suffer the ravages of time.

The Measure of All ThingsKen Adler

Delambre

Mechain

A Unit of Length1790 meter Proposal

One Millionth of the Distance Btwnthe Pole and the Equator along aMeridian running through Paris

Provisional Meter of 1793

Borda, Lagrange, Laplace Estimate = 443.44 lignes(1 pied = 144 lignes)

Triangulation

Link btwn Mechain & Delambre’s TriangulationsHead of the Statue of the Virgin MaryRodez Cathederal

The final step was to embody the meter in a permanent physical standard. CopperHad been sufficient for the provisional meter, but for the definitive meter only ultimateMetal would do. Long despised as a contaminant by South American prospectors, Platinum was difficult to melt, difficult to purify, and nearly indestructable. For justThat reason it had acquired a lustrous reputation among savants. It promised to outlastTime. … The Commission of Weights and Measures spent one fifth of its budgetBuying and refining some one hundred pounds of pure platinum.

In April 1799 [Lenoir] was supplied with the calculated value of the definitive meterAnd four bars of pure platinum, and told to shape four standards of precisely oneMeter each. For this purpose he employed a “comparator” of his own invention,Which could gauge objects to within one millionth of a toise (0.0000072 inches). The task was “diabolically tricky.” Of the four bars, the one that came closest – within0.001 percent of the proper length – was selected as the definitive meter.

1799 Meter

The Measure of All ThingsKen Adler

“Convention of the Meter” - 1875

15 years later the meter was forged.Made of a Platinum-Iridium Alloy.

1963 Meter

Krypton Gas Discharge

1,650,763.73 wavelengths of orange-red light, in a vacuum,producedBy burning the element Kr-86.

1983 Meter

Distance light travels, in a vacuum, in 1/299.792,458 seconds.

Standard Kilogram

US Prototype - 1889

Danish Prototype - 1949

A Unit of Mass

A Unit of Time

The Secondthe duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom

Atomic Clocks at the Naval Observatory

A Unit of Temperature

Triple Point Cells

T = 273.16 Kelvin at the Triple Point of Water

A Unit of Amount

Dozen

Gross Mole

The number of Carbon-12 atoms in a 12 gram sample of Carbon-12.

Avogadro’s Number

6.02214179(30) x 10+23

Units of Electric Current and Luminous Intensity

Current

Galvanometer for Measuring Current

Luminous Intensity

ampere candela