Measurement

JOHN QUINCY ADAMS - Report to the Congress, 1821

“Weights and measures may be ranked among the necessaries of life to every individual of human society. They enter into the economical arrangements and daily concerns of every family. They are necessary to every occupation of human industry; to the distribution and security of every species of property; to every transaction of trade and commerce; to the labors of the husbandman; to the ingenuity of the artificer; to the studies of the philosopher; to the researches of the antiquarian; to the navigation of the mariner, and the marches of the soldier; to all the exchanges of peace, and all the operations of war.”

Standards

• “A standard is something that is used as a comparison for measuring.

– The standard must be available for everyone to use when checking measurements. This means a standard should be something in nature that is the same all over the earth.

– The standard must never vary.“Source =

http://www.howe.k12.ok.us/~jimaskew/ps/pmetric.htm

In all traditional measuring systems, short distance units are based on the dimensions of the human body.

English Customary Units

• Inch• Foot• Yard• Fathom

In Anglo-Saxon England (before the Norman conquest of 1066) the inch (ynce) was defined to be the length of 3 barleycornsbarleycorns, the foot 36 barleycorns and the yard 108.

Longer Distances

• Rod = 5.5 yards (16.5 feet).

• Furlong (fuhrlang) = 40 rods = the length of the traditional furrow (fuhr) as plowed by ox teams on Saxon farms.

• Mile = 8 furlongs

Area

• 1 acre = size field a farmer could plow in 1 day

• 1 square mile = 640 acres

Weight

• Grain = weight of a single barleycornbarleycorn• Roman pound of 12 ounces = troy

pound = 5760 grains. Used for precious metals & pharmaceuticals. Each ounce = 480 grains.

• English pound of 16 ounces = avoirdupois pound = 7000 grains. Each ounce = 437.5 grains.

Larger Weights

• American hundredweight = 100 lbs

• British hundredweight = 112 lbs1 ton = 20 hundredweights

• So American short ton = 2000 lbs

• British long ton = 2240 lbs

Volume (British)

• Until 18th century, standard containers were defined by specifying the weight of a particular substance, such as wheat or beer, that they could carry.

• Gallon was originally the volume of 8 lbs of wheat.

• Gallon = 4 quarts = 8 pints• 2 Gallons = 1 peck. 4 pecks = 1 bushel

Volume (British)

• 1824 – Imperial gallon = 277.42 cubic inches (10 pounds of water)

Volume (American)

• Dry commoditiesDry commodities: 1 gallon = 1/8 th of a bushel. “Corn gallon” holds 268.8 cubic inches

• Liquid commoditiesLiquid commodities: “Wine gallon” holds 231 cubic inches

• Note: the dry units are about 1/6 larger than the corresponding liquid units.

Fluid Ounces

• Roughly equal to the volume of one ounce of water.

• To accomplish this in the different systems, the smaller U.S. pint is divided into 16 fluid ounces, and the larger British pint is divided into 20 fluid ounces.

Congress never established this traditional system, or any other system, as the mandatory system of weights and measures for the United States. In 1832, Congress directed the Treasury Department to standardize the measures used by customs officials at U.S. ports.

• Since 1875 the United States has subscribed to the International System of Weights and Measures, the official version of the metric system.

• One yard equals exactly 0.9144 meter and an avoirdupois pound equals exactly 0.453 592 37 kilograms.

In 1901, Congress established the National Bureau of Standards (NBS), now known as the National Institute of Standards and Technology (NIST), to support technical standards for American industry and commerce.

The Metric System

1585 – Simon Stevin

Introduced the use of decimals in mathematics in Europe. Predicted that the universal introduction of decimal coinage, measures and weights would only be a matter of time.

1670 – Gabriel Mouton

First to propose the decimal system of measurement based on the size of the earth. Also suggested a standard linear measurement, which he called the mille, based on the length of the arc of one degree of longitude on the Earth's surface and divided decimally.

1790 - Jefferson

• Proposed a decimal-based measurement system for the United States.

• Didn’t come up with the prefix idea and his system had too many names.

1792 – U.S. Mint

• Produced world’s first decimal currency (one dollar = 100 cents)

1790 – French Academy of Sciences created the metric

system• The unit of length was to be a portion of the

Earth's circumference.• Measures for capacity (volume) and mass were

to be derived from the unit of length, thus relating the basic units of the system to each other and to nature.

• Larger and smaller multiples of each unit were to be created by multiplying or dividing the basic units by 10 and its powers.

Length

The unit of lengthlength was named the meter.

The meter was to equal one ten-millionth of the distance from the North Pole to the equator along the meridian running near Dunkirk in France and Barcelona in Spain.

Mass

The initial metric unit of mass, the gramgram, was defined as the mass of one cubic centimeter (a cube that is 0.01 meter on each side) of water at its temperature of maximum density.

Volume

The cubic decimetercubic decimeter (a cube 0. 1 meter on each side) was chosen as the unit for capacity. The fluid volume measurement for the cubic decimeter was given the name "literliter."

Important Dates

• 1795 – France adopts metric system• 1889 – U.S. receives prototype meter

and kilogram• 1954 – Initial development of SI

system• 1960 – Meter redefined in terms of

wavelength of light• 1983 – Meter redefined in terms of

speed of light