Chi (unit)
{{Short description|Traditional Chinese unit of length}}
{{Use mdy dates|date=March 2024}}
{{Use American English|date=March 2024}}
{{Infobox transliteration
| title = Chi
| c = {{linktext|尺}}
| p = chǐ
| w = ch'ih3
| bpmf = ㄔˇ
| tp = chǐh
| j = cek3
| y = chek
| kanji = 尺
| kana = しゃく
| revhep = shaku
| hangul = 자
| hanja = n/a
| rr = ja
| mr = cha
| hangul2 = 척
| hanja2 = 尺
| rr2 = cheok
| mr2 = ch'ŏk
| ibox-order = zh, ja, ko1, ko4, ko3}}
{{Infobox unit
| name = Chi (China)
| standard = traditional Chinese unit
| quantity = length
| image = 250px
| caption = Wooden ruler of the western Han dynasty, unearthed at Jinguan Pass Site in Jinta County
| inunits1 = {{sfrac|3}} m
~333.3 mm
| inunits2 = ~{{convert|1/3|m|in|disp=out|lk=on|comma=gaps|sigfig=5}}
}}
{{Infobox unit
| name = Chek (Hong Kong)
| standard = traditional Chinese unit
| quantity = length
| image = 250px
| caption = a section of an old Hong Kong ruler, showing the last (10th) cun of a chi. One can see that the chi in that jurisdiction was exactly equal to {{sfrac|14|5|8}} of an inch. A metric ruler is shown next to it for comparison
| units1 = metric (SI) units
| inunits1 = 371.475 mm
| units2 = imperial/US units
| inunits2 = {{sfrac|14|5|8}} in
}}
{{Infobox unit
| name = Chi (Taiwan)
| standard = traditional Taiwan unit
| quantity = length
| units1 = metric (SI) units
| inunits1 = {{frac|10|33}} m
~303.0 mm
| units2 = imperial/US units
| inunits2 = ~{{convert|10/33|m|in|disp=out|comma=gaps|sigfig=5}}
}}
The chi (Tongyong Pinyin chih) is a traditional Chinese unit of length. Although it is often translated as the "{{nowrap|Chinese foot}}", its length was originally derived from the distance measured by a human hand, from the tip of the thumb to the tip of the forefinger, and is similar to the ancient span. It first appeared during China's Shang dynasty approximately 3,000 years ago and has since been adopted by other East Asian cultures such as Japan (shaku), Korea (ja/cheok), and Vietnam (thước). Its present value is standardized at around {{convert|1/3|m|spell=in|sp=us}}, although the exact standards vary among the mainland of the People's Republic of China, its special administrative region of Hong Kong, and Taiwan.
In its ancient and modern forms, the chi is divided into 10 smaller units known as cun (the "Chinese inch"). 10 chi are equal to 1 zhàng.Shuowen Jiezi (説文解字）, "尺，所以指尺䂓榘事也。" East Asian usually makes spanning with his/her thumb and forefinger, instead of pinkie.
Modern values
In mainland China, the chi is been defined as exactly 1/3 of a meter, i.e., {{cvt|33+1/3|cm}}. However, in Hong Kong the corresponding unit, pronounced tsek (cek3) in Cantonese, is defined as exactly {{cvt|0.371475|m}} or 1 7/32 ft.[https://www.elegislation.gov.hk/hk/cap68a!en/sch0 Cap. 68A WEIGHTS AND MEASURES ORDER ─ SCHEDULE WEIGHTS AND MEASURES CONVERSION TABLE] (Hong Kong e-Legislation) The two units are sometimes referred to in English as "Chinese foot" and "Hong Kong foot".
In Taiwan, chi is the same as the Japanese shaku, i.e., {{convert|10/33|m|2|sp=us}}.{{citation needed|date=November 2023}}
Historical values
The study of ancient rulers and other artifacts whose size in the contemporary chi was known allowed modern researchers to surmise that during the 2nd century BC to 3rd century AD the (Qin dynasty to Han dynasty to the Three Kingdoms period), the value of the chi varied between {{cvt|23.1|and|24.3|cm}}.{{cite book|url=https://books.google.com/books?id=eiTJHRGTG6YC|page=8|
title=The nine chapters on the mathematical art: companion and commentary|first1=Kangshen|last1=Shen|first2=John N.|last2= Crossley|first3= Anthony Wah-Cheung|last3=Lun|first4=Hui|last4= Liu|publisher = Oxford University Press|year= 1999 |
isbn= 0-19-853936-3}} Even earlier, during the Warring States era, the value of chi was essentially the same.{{citation
|first=Ch'ien |last=Ssu-Ma
|publisher=Indiana University Press |year=2008
|isbn=978-0-253-34028-3
|title=The Grand Scribe's Records: The Memoirs of Han China, Part 1. Volume 8 of The Grand Scribe's Records
|url=https://books.google.com/books?id=aLbsTKaO6v0C
|pages=xliv–xlv}}
It is thought that the ancient Chinese astronomers also used the chi as an angular unit; modern analysis of historical records indicates that it may have been equal to one degree.{{cite journal|author=Liu, C. Y.|title=A Research on the Implication of Zhang-Chi in Ancient Chinese Astronomical Records|journal=Acta Astronomica Sinica|volume=28|issue=4|page=402|year=1987|bibcode=1987AcASn..28..397L}}
In the 19th century, the value of the chi, depending on the part of the country and the application, varied between {{cvt|31|and|36|cm|in}}. According to an 1864 British report, in most of China the chi used by engineers in public works was equal to {{convert|12.71|in|cm}}, the surveyors' chi was {{convert|12.058|in|cm}}, while the value generally used for measuring distances was {{convert|12.17|in|cm}}. In Guangzhou, however, the chi used for local trade varied from {{convert|14.625|to|14.81|in|cm}} – i.e., very close to the modern chek. The value fixed by a Sino-British treaty for the purposes of customs duties in Hong Kong was {{convert|14.1|in|cm}}.{{cite book|url=https://books.google.com/books?id=fIgBAAAAQAAJ
|first=Robert C. |last=Carrington
|publisher=Potter |year=1864
|title=Foreign measures and their English values
|page=22
}}
In 1905 the Korean Empire defined the cheok as 10000/33000 of a meter.官報 光武 九年三月二十九日 『度量衡法』。 (Official Gazette, Gwangmu 9 (1905), March 29, "Weights and measures law".) "尺 (米突) ... 三萬三千分之一萬". Available online via [https://www.nl.go.kr/NL/contents/N20301000000.do National Library of Korea "Old Korean Gwanbo"]{{Citation
| title = 도량형 (度量衡)
| trans-title = Weights and measures
| work = 한국민족문화대백과사전
| trans-work = Encyclopedia of Korean Culture
| publisher = Academy of Korean Studies
| url = https://encykorea.aks.ac.kr/Article/E0015586
| access-date = 2024-12-18
}} In 1964, South Korea fully adopted SI units.
==Usage in Chinese language==
Due to its long history and its widespread usage, chi (along with cun) has also seen metaphorical usages in the Chinese language. For example, chi cun ({{zh|t=尺寸}}), a word made up of the units chi and cun, refers to the dimensions of an object, while the idiom "dé cùn jìn chǐ" ({{zh|t=得寸進尺|l=gaining a cun and asking for a chi}}) means "extremely greedy".
In informal use in China, chi is also sometimes used to refer to the United States customary foot or British imperial foot.
References
{{Reflist}}
External links
{{Wiktionary|chi|chek|尺}}