unit

=Unit=

toc Read here about the idea of units with a focus on those aspects that bear on the study of scale.

Definition of unit
The term is used here specifically as a “unit of measurement.” In a context where it may be confused, I use the hyphenated unit-of-measure. A measurement functions in a kind of measurement space, relating to other similar measurements.

The curriculum by Kass writes: A quantity tells us how much or how many and always has two parts—a number and label. For example, do we want 2 feet or 3 feet or 3 miles? Every number must have a unit of measurement or label in order to be a quantity. Example—6 students, 30 cents, 8 inches, $5... Numbers had no meaning in the old days without some unit of measurement such as an arm or foot. The unit of measurement is the measurement label. Without a unit or label, measurement has no meaning. 2 what? 2 arms or 2 feet? Examples—arm, foot, inch, cent, mile. Single and plural labels such as foot or feet are regarded as the same units....

Human-derived Units
Anthropometrics, the study of measurement of people as compared with one another, is outside the scope of this article. In the image below, Vitruvian Man by Leonardo Da Vinci is depicted with nine superimposed historical units of measurement: the Yard, the Span, the Cubit, the Flemish Ell, the English Ell, the French Ell, the Fathom, the Hand, and the Foot. Da Vinci drew the Vitruvian man to scale, so the units depicted here are displayed with their proper historical ratios. >>> image, Vitruvean Man with superimposed historical units of measurement. Public domain.

Area
Quinaria - the cross-sectional area of a pipe created from a flat sheet of lead 5 digits wide Stremma - the amount of land a person can plow in a day

Length
Ald - the distance between a man's outstretched arms Assbā - Arabic finger Beard-second - the length a beard grows in a second Condylos - middle joint of finger Cun - width of the human thumb, at the knuckle Dactylos - Ancient Greek finger breadth Digit - length of a human finger o Digitus - Ancient Roman digit Etzba - fingerbreadth Fathom - the distance between the fingertips of a man's outstretched arms Finger Fistmele - the measure of a clenched hand with the thumb extended Gradus - Ancient Roman step Hand - breadth of a male human hand League - the distance a person can walk in an hour (by one definition) Lichas - thumb length Orgyia - Ancient Greek fathom Parasang - the distance an infantryman could march in a predefined period of time Pygmē - distance from elbow to base of fingers Sazhen - Russian fathom Shaftment - width of the fist and outstretched thumb Smoot - Oliver R. Smoot's height in October 1958 Span - width of a human hand, from the tip of the thumb to the tip of the pinky Spithamē - Ancient Greek span Yard Zeret - Biblical span

Paces
Haploun bēma - Ancient Greek single pace Orgye - Arabic pace Pace - a full stride, from heel to heel Passus - the pace step of a single legionary

Ells
Ell o Scottish ell - length of an average person's arm o Elle - German ell Amah - Biblical ell

Cubits
Arsh - Arabic cubit Cubit - length of the human forearm Macedonian cubit Cubitus - Ancient Roman cubit Pēchys - Ancient Greek cubit

Palms
Cabda - Arabic palm Chetvert/Piad - Russian span/palm Palaistē/dōron - Ancient Greek palm Palm - breadth of four fingers Palmus - Ancient Roman palm Tefah/Tefach - Biblical palm

Inches
Duym - Tatar thumb/inch Inch - length of the thumb (by some definitions) Uncia - Roman inch Zoll - German inch

Feet
Foot - length of the human foot o Arabic foot Fuß - German foot Russian fut - Russian foot Tatar fut - Tatar foot Klafter - German foot Pes - Roman foot Pous - Greek foot

Loudness
Phon Sone

Mass
Picul - the weight a person can carry

Time
Nimesha - the time it takes for a person to blink Paramanu - interval of blinking in humans

Volume
Choenix - a man's daily grain ration Finger tip unit Koku - the amount of rice needed to feed a person for a year Japanese masu - the amount of rice needed to feed a person for a day

Miscellaneous
Fonzie - the amount of coolness inherent in Fonzie Garn - unit of measure for symptoms resulting from space adaptation syndrome; equal to complete incapacitation; named for Jake Garn Smoot - named after Oliver R. Smoot, a fraternity pledge to Lambda Chi Alpha, who in October 1958 lay on the Harvard Bridge (between Boston and Cambridge, Massachusetts), and was used by his fraternity brothers to measure the length of the bridge.

Exponential Units
On most logarithmic scales, small values (or ratios) of the underlying quantity correspond to negative values of the logarithmic measure. Well-known examples of such scales are: Some logarithmic scales were designed such that large values (or ratios) of the underlying quantity correspond to small values of the logarithmic measure. Examples of such scales are: Some measurements do not have their own units but are logarithmic in nature.
 * Richter magnitude scale and moment magnitude scale (MMS) for strength of earthquakes and movement in the earth.
 * ban and deciban, for information or weight of evidence;
 * bel and decibel and neper for acoustic power (loudness) and electric power;
 * cent, minor second, major second, and octave for the relative pitch of notes in music;
 * logit for odds in statistics ;
 * Palermo Technical Impact Hazard Scale;
 * Logarithmic timeline;
 * counting f-stops for ratios of photographic exposure;
 * rating low probabilities by the number of 'nines' in the decimal expansion of the probability of their not happening: for example, a system which will fail with a probability of 10−5 is 99.999% reliable: "five nines".
 * Entropy in thermodynamics.
 * Information in information theory.
 * Particle Size Distribution curves of soil
 * pH for acidity and alkalinity;
 * stellar magnitude scale for brightness of stars;
 * Krumbein scale for particle size in geology.
 * Absorbance of light by transparent samples.
 * Optical density: In spectroscopy, the absorbance A (also called optical density) is defined as:, where I is the intensity of light at a specified wavelength λ that has passed through a sample (transmitted light intensity) and I0 is the intensity of the light before it enters the sample or incident light intensity (or power). Absorbance measurements are often carried out in analytical chemistry, since the absorbance of a sample is proportional to the thickness of the sample and the concentration of the absorbing species in the sample, in contrast to the transmittance I / I0 of a sample, which varies exponentially with thickness and concentration.

Degrees Of Separation
A measure of the distance, in terms of human relationship, that one person is from another. Based on a postcard experiment by the researcher.

=Links and Citations=

See metrology.