View source for Peter Barlow (mathematician)

{{Short description|English mathematician and physicist (1776–1862)}}
{{Use dmy dates|date=August 2020}}
{{Infobox scientist
|name              = Peter Barlow
|image             =Peter Barlow(math).jpg
|image_size       =250px
|caption           = Peter Barlow
|birth_date        = {{birth date|1776|10|13|df=y}}
|birth_place       = [[Norwich]], Norfolk
|death_date        = {{death date and age|1862|03|01|1776|10|13|df=y}}
|death_place       = [[Charlton, London]]
|residence         =
|citizenship       =
|nationality       = English
|ethnicity         =
|field             = [[Mathematics]], [[physics]], [[engineering]]
|work_institutions =
|alma_mater        =
|doctoral_advisor  =
|doctoral_students =
|known_for         = [[Barlow lens]]<br>[[Barlow's wheel]]<br>[[Barlow's formula]]<br>''Barlow's Tables''
|author_abbrev_bot =
|author_abbrev_zoo =
|influences        =
|influenced        =
|prizes            =  [[Copley Medal]] (1825)
|religion          =
|footnotes         =
|signature         =
}}
'''Peter Barlow''' {{post-nominals|FRS}} (13 October 1776 – 1 March 1862)<ref name="eb">[http://www.britannica.com/EBchecked/topic/53519/Peter-Barlow Encyclopædia Britannica Online: Peter Barlow]</ref><ref name="bd">Lance Day and Ian McNeil, ''Biographical dictionary of the history of technology'', Routledge, 1995, page 42.</ref> was an English [[mathematician]] and [[physicist]].

==Work in mathematics==

In 1801, Barlow was appointed assistant mathematics master at the [[Royal Military Academy, Woolwich]],<ref name="eb" /><ref name="mt">[http://www-groups.dcs.st-and.ac.uk/~history/Biographies/Barlow.html MacTutor Biography: Peter Barlow]</ref> and retained this post until 1847.<ref name="bd"/> He contributed articles on mathematics to ''[[The Ladies' Diary]]''<ref name="mt"/> as well as publishing books such as:<ref name="eb"/><ref name="mt"/>
* [https://archive.org/details/anelementaryinv00barlgoog ''An Elementary Investigation of the Theory of Numbers''] (1811);
* [https://archive.org/details/newmathematicalp00barluoft ''A New Mathematical and Philosophical Dictionary''] (1814); and
* [https://archive.org/details/barlowstablesofs00barlrich ''New Mathematical Tables''] (1814).
The latter became known as ''Barlow's Tables'' and gives squares, cubes, square roots, cube roots, and reciprocals of all integer numbers from 1 to 10,000. These tables were regularly reprinted until 1965,<ref name="bd"/> when computers rendered them obsolete.  He contributed to ''[[Rees's Cyclopædia]]'' articles on Algebra, Analysis, Geometry and Strength of Materials. Barlow also contributed largely to the ''[[Encyclopædia Metropolitana]]''.

==Work in physics and engineering==
[[File:Barlow, Peter – Essay on magnetic attractions, and on the laws of terrestrial and electro magnetism, 1824 – BEIC 751993.jpg|thumb|left|''Essay on magnetic attractions, and on the laws of terrestrial and electro magnetism'', 1824]]

In collaboration (1827–1832) with optician [[George Dollond]], Barlow built an [[achromatic lens]] that utilized liquid [[carbon disulfide]]. ([[Achromatic lens]]es were important [[Optics|optical element]]s of improved [[telescope]]s.) In 1833, Barlow built an achromatic [[Doublet (lens)|doublet lens]] of joined [[flint glass]] and [[Crown glass (optics)|crown glass]].<ref name="eb"/><ref name="mt"/> A derivative of this design, named a ''[[Barlow lens]]'', is widely used in modern [[astronomy]] and [[photography]] as an optical element to increase both achromatism and magnification.

In 1823, he was made a fellow of the [[Royal Society]]. Two years later, he received its [[Copley Medal]] for his work on correcting the deviation in ship [[compass]]es caused by the presence of iron in the hull.<ref name="eb"/><ref name="mt"/> Some of his magnetic research was done in collaboration with [[Samuel Hunter Christie]]. He conducted early experimental and observational studies on the origins of [[terrestrial magnetism]].<ref>{{cite book|editor=David Gubbins|editor-link=David Gubbins|editor2=Emilio Herrero-Bervera|author1=Emmanuel Dormy|title=Encyclopedia of geomagnetism and paleomagnetism|pages=40–41|publisher=Springer|year=2007}}</ref> He is credited with ''[[Barlow's wheel]]'' (an early [[homopolar motor|homopolar]] [[electric motor]]) and with ''[[Barlow's law]]'' (an incorrect formula of electrical conductance).

Barlow investigated a suggestion made by [[André-Marie Ampère]] in 1820 that an [[Electric telegraph|electromagnetic telegraph]] could be made by deflecting a compass needle with an electric current.  In 1824 Barlow proclaimed the idea impractical after he found that the effect on the compass seriously diminished "with only 200 feet of wire".  Barlow, and other eminent scientists of the time who agreed with him, are criticised for retarding the development of the telegraph.  A decade passed between Ampère's paper being read at the [[Paris Academy of Sciences]] and [[William Ritchie (physicist)|William Ritchie]] building the first demonstration electromagnetic telegraph.  In Barlow's defence, Ampère's design did not enclose the compass in a multiplying coil, as Ritchie's demonstrator did, so the effect would have been very weak at a distance.<ref>Fahie, John Joseph, [https://archive.org/details/cu31924031221249/page/n9/mode/2up ''A History of Electric Telegraphy, to the Year 1837''], pp. 302–307, London: E. & F.N. Spon, 1884 {{oclc|559318239}}.</ref>

[[Steam locomotive|Steam locomotion]] received much attention at Barlow's hands and he sat on the railway commissions of 1836, 1839, 1842 and 1845. He also conducted several investigations for the newly formed [[Railway Inspectorate]] in the early 1840s.

[[File:Peter Barlow FRS - gravestone in Charlton Cemetery, London SE7.jpg|thumb|Peter Barlow FRS – gravestone in Charlton Cemetery, London SE7]]
Barlow made several contributions to the theory of [[strength of materials]], including ''Essay on the strength and stress of timber'' (1817) which contains experimental data collected at Woolwich. The sixth edition (1867) of this work was prepared by Barlow's two sons after his death and contains a biography of their father.  Barlow also applied his knowledge of materials to the design of bridges.<ref name="mt"/> His sons [[Peter W. Barlow]] and [[William Henry Barlow]] became notable [[civil engineer]]s of the 19th century. He was elected a Foreign Honorary Member of the [[American Academy of Arts and Sciences]] in 1832.<ref name=AAAS>{{cite web |title=Book of Members, 1780-2010: Chapter B |url=http://www.amacad.org/publications/BookofMembers/ChapterB.pdf |url-status=dead |archive-url=https://web.archive.org/web/20110612080006/http://www.amacad.org/publications/BookofMembers/ChapterB.pdf |archive-date=2011-06-12 |publisher=American Academy of Arts and Sciences |access-date=17 May 2011}}</ref>

Following his death in 1862 at his home in Charlton,<ref>{{Cite newspaper The Times |title=Deaths |date=4 March 1862 |page=1 |issue=24184 }}</ref> he was buried in [[Charlton Cemetery]].

==See also==

* [[2147483647]], Barlow commented on this [[Mersenne prime]]

==References==

{{Wikisource1911Enc|Barlow, Peter}}

{{Reflist}}

==External links==
{{Commons category|Peter Barlow}}
{{Wikiquote}}
*[https://web.archive.org/web/20160204025513/http://aerocomfittings.com/barlows.html Barlow's Formula Calculator ]
*[https://web.archive.org/web/20090615031452/http://www.barlowgenealogy.com/england/famous/Petersbio.htm Biographical information]

{{Copley Medallists 1801-1850}}

{{Authority control}}

{{DEFAULTSORT:Barlow, Peter}}
[[Category:1776 births]]
[[Category:1862 deaths]]
[[Category:Fellows of the Royal Society]]
[[Category:19th-century English mathematicians]]
[[Category:English scientists]]
[[Category:Recipients of the Copley Medal]]
[[Category:Scientists from Norwich]]
[[Category:18th-century English people]]
[[Category:Fellows of the American Academy of Arts and Sciences]]