{{short description|German geodesist}} {{more footnotes needed|date=November 2009}} {{Infobox scientist |name = Friedrich Robert Helmert | image = F-R Helmert 1.jpg |caption = '''Professor Friedrich Robert Helmert'''. Photographer unknown. |birth_date = {{Birth date|df=yes| 1843|07|31}} |birth_place = [[Freiberg, Saxony|Freiberg]], [[Kingdom of Saxony]] |death_date = {{Death date and age|df=yes| 1917|06|15|1843|07|31}} |death_place = [[Potsdam]], [[Germany]] |residence = |alma_mater = Polytechnische Schule, now Technische Universität, in Dresden, [[University of Leipzig]] |known_for = contribution into [[geodesy]] and [[theory of errors]]. |footnotes = |spouse = |children = |field = [[Mathematics]], [[geodesy]] |work_institutions = [[RWTH Aachen|Technical University in Aachen]], [[University of Berlin]]. |advisor = |prizes = recipient of some 25 German and foreign decorations |religion = }}
'''Friedrich Robert Helmert''' (31 July 1843 – 15 June 1917) was a German [[geodesist]] and [[statistician]] with important contributions to the [[theory of errors]].
==Career== Helmert was born in [[Freiberg, Saxony|Freiberg]], [[Kingdom of Saxony]]. After schooling in Freiberg and [[Dresden]], he entered the Polytechnische Schule, now Technische Universität, in Dresden to study engineering science in 1859. Finding him especially enthusiastic about geodesy, one of his teachers, {{ill|Christian August Nagel|de}}, hired him while still a student to work on the {{ill|Royal Saxon Triangulation|de|Königlich-Sächsische Triangulirung}} of the [[Ore Mountains]] and the drafting of the trigonometric network for Saxony. In 1863 Helmert became Nagel's assistant on the [[Central European Arc Measurement]]. After a year's study of mathematics and astronomy Helmert obtained his doctor's degree from the [[University of Leipzig]] in 1867 for a thesis based on his work for Nagel.
In 1870 Helmert became instructor and in 1872 professor at [[RWTH Aachen]], the new Technical University in [[Aachen]]. At Aachen he wrote ''Die mathematischen und physikalischen Theorieen der höheren Geodäsie'' (Part I was published in 1880 and Part II in 1884). This work laid the foundations of modern [[geodesy]]. See [[history of geodesy]]. Part I is devoted to the mathematical aspects of geodesy and contains a comprehensive summary of techniques for solving for [[geodesics on an ellipsoid]].
The method of [[least squares]] had been introduced into geodesy by [[Carl Friedrich Gauss|Gauss]] and Helmert wrote a fine book on least squares (1872, with a second edition in 1907) in this tradition, which became a standard text.{{sfn|Hald|1998|p=633|ps=: "[It] is a pedagogical masterpiece; it became a standard text until it was superseded by expositions using matrix algebra."}} In 1876 he discovered the [[chi-squared distribution]] as the distribution of the sample variance for a [[normal distribution]].{{sfn|Hald|1998|pp=633–692|loc=27. Sampling Distributions under Normality}}<ref>F. R. [[Helmert]], "[http://gdz.sub.uni-goettingen.de/dms/load/img/?PPN=PPN599415665_0021&DMDID=DMDLOG_0018 Ueber die Wahrscheinlichkeit der Potenzsummen der Beobachtungsfehler und über einige damit im Zusam- menhange stehende Fragen]", ''Zeitschrift für Mathematik und Physik'' [http://gdz.sub.uni-goettingen.de/dms/load/toc/?PPN=PPN599415665_0021 21], 1876, pp. 192–219</ref> This discovery and other of his work was described in German textbooks, including his own, but was unknown in English, and hence later rediscovered by English statisticians – the chi-squared distribution by [[Karl Pearson]] (1900), and the application to the sample variance by [[William Sealey Gosset|'Student']] and [[Ronald Fisher|Fisher]].
From 1887 Helmert was professor of advanced geodesy at the [[University of Berlin]] and director of the Geodetic Institute. In 1916 he had a stroke and died of its effects the following year in [[Potsdam]].
[[File:Stein.Helmert.jpg|thumb|200px|Commemorative headstone in honor of Friedrich Robert Helmert (Telegraph Hill in Potsdam)]]
==Honours== Helmert received many honours. He was president of the global [[geodesy|geodetic]] association of "[[International Earth Rotation and Reference Systems Service|Internationale Erdmessung]]", member of the [[Prussian Academy of Sciences]] in [[Berlin]], was elected a member of the [[Royal Swedish Academy of Sciences]] in 1905, and recipient of some 25 German and foreign decorations.
The lunar crater [[Helmert (crater)|Helmert]] was named in his honor, approved by the [[International Astronomical Union|IAU]] in 1973.<ref>[https://planetarynames.wr.usgs.gov/Feature/2437 Helmert], Gazetteer of Planetary Nomenclature, International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN)</ref>
==See also== *[[Coordinate system]] *[[Gauss–Helmert model]] *[[Geodesics on an ellipsoid]] *[[Gravity of Earth#Mathematical models|Helmert's equation]] *[[Helmert transformation]] (in geodesy) *[[Helmert–Wolf blocking]] *[[National survey]] *Terrestrial [[gravity field]]
==References== {{citation style|date=September 2020}} {{reflist}}
{{refbegin}}
===Works cited=== * {{cite book |title=A history of mathematical statistics from 1750 to 1930 |last=Hald |first=Anders |author-link=Anders Hald |year=1998 |publisher=Wiley |location=New York |isbn=978-0-471-17912-2 }}
===General references=== * Walther Fischer "Helmert, Friedrich Robert" ''Dictionary of Scientific Biography'' volume 7, pp. 239–241, New York: Scribners 1973. *O. B. Sheynin (1995). "Helmert's work in the theory of errors". ''Archive for History of Exact Sciences,'' 49, 73–104. *Die Genauigkeit der Formel von [[Christian August Friedrich Peters|Peters]] zur Berechnung des wahrscheinlichen Fehlers director Beobachtungen gleicher Genauigkeit, [http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1876AN.....88..113H&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf ''Astron. Nach.,'' 88, (1876), 192–218] An extract from the paper is translated and annotated in [[Herbert A. David]] & [[A. W. F. Edwards]] (eds.) ''Annotated Readings in the History of Statistics'', New York: Springer 2001. * {{cite journal | last1=Ihde | first1=Johannes | last2=Reinhold | first2=Andreas | title=Friedrich Robert Helmert, founder of modern geodesy, on the occasion of the centenary of his death | journal=History of Geo- and Space Sciences | publisher=Copernicus GmbH | volume=8 | issue=2 | date=2017-08-08 | issn=2190-5029 | doi=10.5194/hgss-8-79-2017 | pages=79–95| bibcode=2017HGSS....8...79I | doi-access=free }} * {{cite journal | last=Witte | first=Bertold | title=Friedrich Robert Helmert in memory of his 100th year of death | journal=GEM - International Journal on Geomathematics | publisher=Springer Science and Business Media LLC | volume=8 | issue=2 | date=2017-10-25 | issn=1869-2672 | doi=10.1007/s13137-017-0098-3 | pages=153–168| bibcode=2017IJGm....8..153W | s2cid=126314185 }} {{refend}}
==External links== {{commons category|Friedrich Robert Helmert}} {{wikisource|works=or}} *[http://www.royalsoc.ac.uk/DServe/dserve.exe?dsqIni=Dserve.ini&dsqApp=Archive&dsqCmd=Show.tcl&dsqDb=Catalog&dsqSearch=(PersonCode=='NA377') Royal Society citation 1908 (very succinct)]
There is an obituary at * [http://adsabs.harvard.edu//full/seri/MNRAS/0078//0000256.000.html MNRAS '''78''' (1918) 256]
There is a photograph of Helmert at *[http://www.york.ac.uk/depts/maths/histstat/people/helmert.gif Helmert] on the [http://www.york.ac.uk/depts/maths/histstat/people/welcome.htm Portraits of Statisticians] page
and three more at *[http://www.klima-luft.de/steinicke/ngcic/persons/helmert.htm Helmert]
See also *[http://www.w-volk.de/museum/memori02.htm memorial stone]
The first edition of Helmert's textbook on least squares is available at the GDZ site *[http://www-gdz.sub.uni-goettingen.de/cgi-bin/digbib.cgi?PPN309768101 ''Die Ausgleichsrechnung nach der Methode der kleinsten Quadrate''] (''[[Adjustment Computations]] by the Method of Least Squares'')
A partial scan of ''Die mathematischen und physikalischen Theorieen der höheren Geodäsie'' (Part I) is available on the site *[http://fkf.net/Helmert.html Friedrich Robert Helmert (1841–1917)]
English translations (by the Aeronautical Chart and Information Center, St. Louis) of Parts I and II of ''Die mathematischen und physikalischen Theorieen der höheren Geodäsie'' are available at *[https://dx.doi.org/10.5281/zenodo.32050 doi:10.5281/zenodo.32050] *[https://dx.doi.org/10.5281/zenodo.32051 doi:10.5281/zenodo.32051]
There is an account of Helmert's work on the theory of errors in section 10.6 of *[http://www.sheynin.de/download/double.pdf Oscar Sheynin Theory of Probability: A Historical Essay]
For eponymous terms in statistics see *[http://jeff560.tripod.com/a.html Earliest known uses of some of the words of mathematics: A] for the Abbe–Helmert criterion and [http://jeff560.tripod.com/h.html Earliest known uses of some of the words of mathematics: H] for the Helmert transformation.
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{{DEFAULTSORT:Helmert, Friedrich Robert}} [[Category:1843 births]] [[Category:1917 deaths]] [[Category:German statisticians]] [[Category:German geodesists]] [[Category:People from the Kingdom of Saxony]] [[Category:Leipzig University alumni]] [[Category:Academic staff of RWTH Aachen University]] [[Category:Academic staff of the Humboldt University of Berlin]] [[Category:Members of the Prussian Academy of Sciences]] [[Category:Members of the Royal Swedish Academy of Sciences]] [[Category:Foreign members of the Royal Society]] [[Category:Spatial statisticians]]