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((short description|Indian mathematician (1813–1870)))
((More citations needed|date=October 2020))
((EngvarB|date=September 2014))
((Use dmy dates|date=September 2014))
((Infobox person
| name               = Radhanath Sikdar
| honorific prefix   =
| image              = Radhanath Sikdar.jpg
| caption            = Radhanath Sikdar
| birth_name         = 
| birth_date         = ((birth date|1813|10|5|df=y))
| birth_place        = [[Jorasanko]], [[Kolkata|Calcutta]], [[Bengal Presidency]]  
| death_date         = ((death date and age|1870|5|17|1813|10|5|df=y))
| death_place        = [[Chandannagar|Chandernagore]], [[Hooghly district]], [[Bengal Presidency]] 
| alma_mater         = [[Presidency College, Kolkata|Presidency College]] ([[Bachelor of Arts|BA]])
| occupation         = 
| years_active       = 
| nationality        = [[British India]]n
| works              = 
| height             = 
| spouse             = 
| children           = 
| father             = Tituram Sikdar
| mother             = Devki Sikdar
| relatives          = Srinath Sikdar (brother) 
| awards             = 
| website            = 
| signature          = 
))
'''Radhanath Sikdar''' (Bengali: রাধানাথ শিকদার; 5 October 1813 – 17 May 1870) was an Indian mathematician who is best known for calculating the height of [[Mount Everest]].<ref>((Cite news|date=2003-10-20|title=The man who 'discovered' Everest|language=en-GB|url=http://news.bbc.co.uk/2/hi/south_asia/3193576.stm|access-date=2021-01-14))</ref> He was the first person to calculate the height of Mount Everest, in 1852.<ref>((cite news|url=https://www.hindustantimes.com/cities/kolkata-news/call-to-rename-mt-everest-after-radhanath-sikdar-who-measured-its-height-101622341596693.html|title=Call to rename Mt Everest after Radhanath Sikdar, who measured its height|publisher=[[Hindustan Times]]))</ref><ref>((cite news|url=https://www.bbc.com/future/article/20220407-how-tall-will-mount-everest-get-before-it-stops-growing|title=How tall will Mount Everest get before it stops growing?|publisher=[[BBC Online]]))</ref>

==Great Trigonometric Survey==
In 1831, [[George Everest]], the Surveyor General of India, was in the pursuit of a mathematician who had specialised in [[Spherical trigonometry|Spherical Trigonometry]], so that they could be a part of the [[Great Trigonometrical Survey|Great Trigonometric Survey.]] In 1832, under the leadership of Everest, the longitudinal series of the "triangle" survey was completed from [[Sironj]] in [[Central India Agency|Central India]] to [[Kolkata|Calcutta]] in [[Bengal Presidency|Bengal]].

While still working on mapping Calcutta, Bengal, Everest had begun his search for a mathematician, and soon enough, [[John Tytler (surgeon)|John Tytler]], a professor of Mathematics at the Hindu College, now known as the [[Presidency College Calcutta|Presidency College]], recommended his 19-year-old pupil, Radhanath Sikdar.

Radhanath, a student of the college since 1824, was one of the first two Indians to read [[Isaac Newton]]'s ''[[Philosophiæ Naturalis Principia Mathematica|Principia]]'' and by 1832; he had studied [[Euclid]]'s [[Euclid's Elements|''Elements'']], Thomas Jephson's ''Fluxion'' and [[Analytic geometry|Analytical Geometry]] and [[Astronomy]] by Windhouse. Taking inspiration from these prestigious papers, he devised a new method to draw a common tangent to two circles, when he was just a teenager. There was little doubt about Radhanath's proficiency in his subject, and he secured the job at the GTS on 19 December 1831 as a "computer" at a salary of thirty rupees per month.

Soon he was sent to Sironj near [[Dehradun]]. Even as seven other Bengali ‘computers’ worked alongside him, Radhanath soon showed his superior skills in mathematics and became Everest’s favourite colleague. So much so, that he once stopped his transfer to another department. Radhanath’s job was to carry geodetic surveys—the study of the earth’s geometric shape orientation in space and gravitational field. He did not just use the established methods but invented his own to accurately measure these factors.

George Everest retired in 1843 and was succeeded by Colonel [[Andrew Scott Waugh]]. Eight years later, in 1851, Radhanath was promoted to the position of Chief Computer and transferred to Calcutta. Here, he was also a superintendent for the Meteorological Department.

At the order of Colonel Waugh, Radhanath started measuring the height of mountains. The brilliant mathematician, who had perhaps never seen [[Mount Everest]], discovered in 1852 that [[Kangchenjunga]], which was considered to be the tallest in the world, wasn’t really so. Compiling data about Mount Everest from six observations, he eventually came to the conclusion that it was the tallest in the world.

It was during the computations of the northeastern observations that Radhanath had calculated the height of Peak XV at exactly 29,000&nbsp;ft (8839 m), but Waugh added an arbitrary two feet because he was afraid that the Sikdar’s figure would be considered a rounded number rather than an accurate one. He officially announced this finding in March 1856, and this remained the height of [[Mount Everest]] till an Indian survey re-calculated it to be 29,029&nbsp;ft or 8848 m in 1955.

Technological advancements, data from the thousands of climbers, and the discovery of different routes to the summit all have led to a more accurate calculation of the height of Mount Everest—a peak that grows at the rate of 4&nbsp;mm every year and whose summit is slowly moving northeastwards each passing year.

==Others==
It appears that while Everest and Waugh both extolled him for his exceptional mathematical abilities, his relations with the colonial administration were far from cordial. Two specific instances are on record.

In 1851 a Survey Manual (eds. Capt. H. L. Thullier and Capt. F. Smyth) was published by the Survey Department. The preface to the Manual mentions that the more technical and mathematical chapters of the Manual were written by Babu Radhanath Sikdar. The Manual proved to be immensely useful to surveyors.  However, the third edition, published in 1875 (i.e., after Sikdar's death) did not contain that preface, so that Sikdar's memorable contribution was de-recognized. The incident was condemned by a section of British surveyors. The paper ''[[The Statesman (India)|Friend of India]]'' in 1876 called it 'robbery of the dead'.<ref name=lahiri>For details, see Ashish Lahiri, ''Radhanath Sikdar: Beyond the Peak'', Boi-Chitra, Kolkata, 2010.</ref>

It is also on record that Sikdar was fined a sum of 200 rupees in 1843 for having vehemently protested against the unlawful exploitation of survey department workers by the Magistrate Vansittart. The incident was reported in detail in ''The Bengal Spectator'' edited by [[Ramgopal Ghosh]].<ref name=lahiri/>

In 1854, Sikdar along with his [[Young Bengal|Derozian]] friend [[Peary Chand Mitra]] started the Bengali journal ''Masik Patrika'', for education and empowerment of women.  He used to write in a simple and uncluttered style that was rather atypical for the age.

Sikdar had retired from service in 1862, and was later appointed as teacher of mathematics at the General Assembly's Institution (now [[Scottish Church College]]).<ref name=Banglapedia_article>((cite web|last1=Hasnat|first1=Abul|title=Shikder, Radhanath|url=http://en.banglapedia.org/index.php?title=Shikder,_Radhanath|website=Banglapedia|accessdate=26 July 2015))</ref><ref name=GAI>''Staff List: General Assembly's Institution (1856-1907)'' in ''175th Year Commemoration Volume''. Scottish Church College, April 2008. page 569</ref>

==Death==
He died on 17 May 1870 at Chandernagore and was interred at the [[Sacred Heart Church, Chandannagar|Sacred Heart Cemetery]].

==Recognition==
In recognition of Sikdar's mathematical genius, German Philosophical Society's Bavaria branch of Natural Science made Radhanath Sikdar a Corresponding Member in 1864, two years after his retirement.<ref>((cite news|url=https://www.telegraphindia.com/my-kolkata/people/radhanath-sikdar-a-past-we-must-preserve/cid/1810215|title=Radhanath Sikdar: A past we must preserve|publisher=[[The Telegraph (India)]]))</ref>

The [[Indian Postal Service|Department of Posts, Government of India]], launched a postal stamp on 27 June 2004, commemorating the establishment of the [[Great Trigonometric Survey]] in [[Chennai]], India on 10 April 1802. The stamps feature Radhanath Sikdar and [[Nain Singh]], two significant contributors to society.<ref>((cite news|url=https://www.thehindu.com/sci-tech/science/when-did-modern-science-emerge-in-india/article26037575.ece|title=When did modern science emerge in India?|work=[[The Hindu]]))</ref>

==References==
((reflist))

==Notes==
* Bagal, Jogesh Chandra ''Unabingsha Shatabdir Bangla'', 1941
* Chaudhury, Ajana ''A Brief Historical Review of Early Weather Work in Kolkata'', Psyche and Society, Kolkata, May 2009
* Lahiri, Ashish ''Radhanath Sikdar and Colonial Science'', Sahitya Samsad, Kolkata, 2017
* Nath, Sankar Kumar  ''Radhanath Sikdar: Taththeyer Aaloye'', Chirayata, Kolkata-73, October 2012

((Authority control))

((DEFAULTSORT:Sikdar, Radhanath))
[[Category:1813 births]]
[[Category:1870 deaths]]
[[Category:Bengali Hindus]]
[[Category:19th-century Bengalis]]
[[Category:Bengali mathematicians]]
[[Category:Bengali scientists]]
[[Category:Indian diarists]]
[[Category:Indian surveyors]]
[[Category:Indian mathematicians]]
[[Category:19th-century Indian mathematicians]]
[[Category:Scientists from Kolkata]]
[[Category:Hare School alumni]]
[[Category:Presidency University, Kolkata alumni]]
[[Category:Academic staff of Scottish Church College]]
[[Category:Academic staff of the University of Calcutta]]
[[Category:Human computers]]

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