Hair's breadth

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Scanning electron microscope image of a human hair Human hair 2000X - SEM MUSE.tif
Scanning electron microscope image of a human hair

A hair's breadth, or the width of human hair , is used as an informal unit of a very short length. [1] It connotes "a very small margin" or the narrowest degree in many contexts. [2] [3] [4] [5] [6] [7]

Contents

Definitions

This measurement is not precise because human hair varies in diameter, ranging anywhere from 17 μm to 181 μm [millionths of a metre] [8] One nominal value often chosen is 75 micrometres (0.0030 in), [5] but this – like other measures based upon such highly variable natural objects, including the barleycorn [9]  – is subject to a fair degree of imprecision. [5] [7]

Such measures can be found in many cultures. The English "hair's breadth" [6] has a direct analogue in the formal Burmese system of Long Measure. A "tshan khyee", the smallest unit in the system, is literally a "hair's breadth". 10 "tshan khyee" form a "hnan" (a Sesamum seed), 60 (6 hnan) form a mooyau (a species of grain), and 240 (4 mooyau) form an "atheet" (literally, a "finger's breadth"). [10] [11]

Some formal definitions even existed in English. In several systems of English Long Measure, a "hair's breadth" has a formal definition. Samuel Maunder's Treasury of Knowledge and Library of Reference, published in 1855, states that a "hair's breadth" is one 48th of an inch (and thus one 16th of a barleycorn). [12] John Lindley's An introduction to botany, published in 1839, and William Withering' An Arrangement of British Plants, published in 1818, states that a "hair's breadth" is one 12th of a line, which is one 144th of an inch or ~176 μm (a line itself being one 12th of an inch). [13] [14] Carl Linnaeus had earlier recommended, in place of Joseph Pitton de Tournefort's geometric scale for botanical measurements, a scale starting with a "hair's breadth" (capillus) which was one 12th of a line (linea), one 6th of a (finger) nail (unguis), and likewise 144th of a thumb (pollex); which itself was equal to a (Parisian) inch. [15]

Other body part measurements

Winning a competition, such as a horse race, "by a whisker" (a short beard hair) is a narrower margin of victory than winning "by a nose." [16] [17] An even narrower anatomically-based margin might be described in the idiom "by the skin of my teeth," which is typically applied to a narrow escape from impending disaster. This is roughly analogous to the phrase "as small as the hairs on a gnat's bollock." [18] Some German speakers similarly use “Muggeseggele,” literally “housefly’s scrotum,” as a small unit of measurement. [19]

See also

References

Notes

    Citations

    1. ↑ "Hair's breadth (hare's breath)". Grammarist. 10 February 2011. Retrieved January 27, 2015.
    2. ↑ Hairs breadth. Archived from the original on February 3, 2015. Retrieved January 28, 2015.{{cite book}}: |work= ignored (help)
    3. ↑ "Hairs breadth". Macmillan English Dictionary . Retrieved January 27, 2015.
    4. ↑ "Hairs breadth". Cambridge Dictionary . Retrieved January 27, 2015.
    5. 1 2 3 Smith 2002, p. 253.
    6. 1 2 Crook & Osmaston 1994, p. 133.
    7. 1 2 Johnson 1842, pp. 1257.
    8. ↑ Ley, Brian (1999). Elert, Glenn (ed.). "Diameter of a human hair". The Physics Factbook. Retrieved 2018-12-08.
    9. ↑ Boaz 1823, p. 267.
    10. ↑ Latter 1991, pp. 167.
    11. ↑ Carey 1814, p. 209.
    12. ↑ Maunder 1855, p. 12.
    13. ↑ Lindley 1839, p. 474.
    14. ↑ Withering 1818, p. 69.
    15. ↑ Milne 1805, pp. 417–418.
    16. ↑ "Win by a nose". The American Heritage® Idioms Dictionary. Houghton Mifflin Company/Dictionary.com. 2002. Retrieved January 27, 2015.
    17. ↑ "By a nose". Free Dictionary. Retrieved December 30, 2016.
    18. ↑ "The meaning and origin of the expression: By the skin of your teeth". The phrase finder. Retrieved January 28, 2015.
    19. ↑ Sellner, Jan (9 March 2009). "Schönstes schwäbisches Wort: Großer Vorsprung für Schwabens kleinste Einheit". Stuttgarter Nachrichten (in German). Archived from the original on 27 September 2013. Retrieved 13 August 2013.

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    Further reading