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{{Short description|English optician (1706–1761)}}
{{Use dmy dates|date=July 2016}}
{{Use British English|date=July 2016}}
{{Infobox scientist
|name              = John Dollond
|honorific_suffix  = {{post-nominals|country=GBR|size=100%|FRS}}
|image             = John Dollond, by Benjamin Wilson.jpg
|caption           = Painting by [[Benjamin Wilson (painter)|Benjamin Wilson]], {{circa|1760}}
|birth_date        = {{OldStyleDate|21 June|1706|10 June}}
|birth_place       = London, England
|death_date        = {{death date and age|1761|11|30|1706|6|21|df=yes}}
|death_place       = London, England
|spouse            = {{marriage|Elizabeth Sommelier|1729}}
|children          = 5
|field             = {{hlist|[[Optics]]|[[astronomy]]}}
|known_for         = [[Achromatic doublet]]
|prizes            = [[Copley Medal]] (1758)
}}

'''John Dollond''' {{post-nominals|country=GBR|FRS}} ({{OldStyleDate|21 June|1706|10 June}}{{snd}}30 November 1761)<ref>{{Britannica|168291|title=John Dollond}}</ref> was an English [[optician]], known for his successful optics business and his patenting and commercialization of [[Achromatic lens|achromatic doublet]]s.

==Biography==
Dollond was the son of a [[Huguenot]] refugee, a [[silk]]-weaver at [[Spitalfields]], London, where he was born. He followed his father's trade, but found time to acquire a knowledge of [[Latin]], [[Greek language|Greek]], [[mathematics]], [[physics]], [[anatomy]] and other subjects. In 1752 he abandoned silk-weaving and joined his eldest son, [[Peter Dollond]] (1731–1820), who in 1750 had started in business as a maker of optical instruments; this business went on to become [[Dollond & Aitchison]]. His reputation grew rapidly, and in 1761 he was appointed optician to the king.<ref name="EB1911"/>

In 1758 he published an "Account of some experiments concerning the different refrangibility of light",<ref>{{cite journal |last1=Dollond |first1=John |date=1758 |title=Account of some experiments concerning the different refrangibility of light |url=https://www.jstor.org/stable/105323 |journal=Philosophical Transactions |volume=50 (1757 - 1758) |publisher=Royal Society |pages=733–743 |jstor=105323 |access-date=11 Feb 2025}}</ref> describing the experiments that led him to the achievement with which his name is specially associated, the discovery of a means of constructing [[achromatic lens]]es by the combination of [[crown glass (optics)|crown]] and [[flint glass]]es, reducing or eliminating [[chromatic aberration]] (distortion due to colour fringes). [[Leonhard Euler]] in 1747 had suggested that achromatism might be obtained by the combination of glass and water lenses. Relying on statements made by Sir [[Isaac Newton]], Dollond first disputed this possibility (''Phil. Trans.'', 1753), but subsequently, after the Swedish physicist, [[Samuel Klingenstierna]] (1698–1765), had pointed out that Newton's law of dispersion did not harmonize with certain observed facts, Dollond began experiments to settle the question.<ref name="EB1911"/>

Early in 1757 Dollond succeeded in producing achromatic refraction by the aid of glass and water lenses, and a few months later he made a successful attempt to get the same result by a combination of glasses of different qualities (see [[History of telescopes]]). For this achievement the [[Royal Society]] awarded him the [[Copley Medal]] in 1758, and three years later elected him one of its fellows. Dollond also published two papers on apparatus for measuring small angles (''Phil. Trans.'', 1753, 1754).<ref name="EB1911">{{EB1911|inline=1|wstitle=Dollond, John|volume=8|page=392}}</ref>

In 1761, Dollond became the optician of King [[George&nbsp;III]]. He died of [[apoplexy]] on 30 November, of that year in London.<ref name="BootsUK">{{cite web |title=Boots Hidden Heroes - John Dollond |url=https://www.boots-uk.com/newsroom/features/boots-hidden-heroes-john-dollond/ |website=Boots UK |access-date=29 July 2023}}</ref>

{{quotation| Mr Dolland’s appearance was somewhat stern, and his address and language impressive; but his manners were cheerful, kind and affable. He adhered to the religion of his father, and attended the French Protestant Church, of which his life and conversation rendered him an ornament.<ref>{{cite book |title=The National Cyclopaedia of Useful Knowledge |date=1848 |publisher=Charles Knight |location=London |page=494 | volume=V |edition=First}}</ref>}}

==Family==
He married Elizabeth Sommelier in 1729.<ref name="BootsUK" /> They had two sons and three daughters.<ref>{{cite book |last1=Rudd |first1=M. Eugene |chapter=Dollond, John |title=The Biographical Encyclopedia of Astronomers |date=2007 |pages=303 |doi=10.1007/978-0-387-30400-7_369 |isbn=978-0-387-31022-0 |chapter-url=https://link.springer.com/referenceworkentry/10.1007/978-0-387-30400-7_369}}</ref> Their daughter, Sarah Dollond, married his neighbour and friend, the mathematician and instrument maker [[Jesse Ramsden]].<ref>{{Cite web |url=http://www-groups.dcs.st-and.ac.uk/history/Biographies/Ramsden.html |title=Jesse Ramsden - Biography |website=www-groups.dcs.st-and.ac.uk |access-date=2 February 2018 |archive-date=2 May 2012 |archive-url=https://web.archive.org/web/20120502234104/http://www-groups.dcs.st-and.ac.uk/history/Biographies/Ramsden.html |url-status=dead}}</ref>

==Priority of invention==
{{see also|Achromatic lens#History|History of the telescope#Achromatic refracting telescopes}}
[[File:Lens6b-en.svg|thumb|Dollond patented the [[achromatic doublet]], which combines [[crown glass (optics)|crown glass]] and [[flint glass]].]]
A theoretical approach to reduce chromatic aberration was worked out by [[Leonhard Euler]] in papers that he published in the Memoires of the Berlin Academy between 1747 and 1753. John Dollond read the paper and conducted experiments to construct an achromatic lens and was the first person to patent the [[achromatic doublet]] which was granted on 19 April 1758 for a period of 14 years.<ref name=Stargazer>{{cite book |url=https://books.google.com/books?id=2LZZginzib4C&pg=PA140 |title=Stargazer: the life and times of the telescope |first=Fred |last=Watson |publisher=[[Allen & Unwin]] |date=2007 |pages=140–55 |isbn=978-1-74175-383-7}}</ref> However, he was not the first to make such lenses. Optician [[George Bass (optician)|George Bass]], following the instructions of [[Chester Moore Hall]], made and sold such lenses as early as 1733.<ref name="daumas">Daumas, Maurice,  ''Scientific Instruments of the Seventeenth and Eighteenth Centuries and Their Makers'', Portman Books, London 1989  {{ISBN|978-0-7134-0727-3}}</ref> In the late 1750s, Bass told Dollond about Hall's design; Dollond saw the potential and was able to reproduce them.<ref name=Stargazer/><ref>{{Cite journal |last=Willach|first=R. |date=1996-07-31 |title=New light on the invention of the achromatic telescope objective |url=https://royalsocietypublishing.org/doi/10.1098/rsnr.1996.0022 |journal=Notes and Records of the Royal Society of London |language=en |volume=50 |issue=2 |pages=195–210 |doi=10.1098/rsnr.1996.0022 |s2cid=144123672 |issn=0035-9149|url-access=subscription }}</ref>

Dollond appears to have known of the prior work and refrained from enforcing his patent.<ref name="daumas"/>  After his death, his son, Peter, did take action to enforce the patent.  A number of his competitors, including Bass, [[Benjamin Martin (lexicographer)|Benjamin Martin]], Robert Rew and [[Jesse Ramsden]], took action. Dollond's patent was upheld, as the court found that the patent was valid due to Dollond's ''exploitation'' of the invention while prior inventors did not.  Several of the opticians were ruined by the expense of the legal proceedings and closed their shops as a result. The patent remained valid until it expired in 1772.<ref name="daumas"/>  Following the expiry of the patent, the price of achromatic doublets in England dropped by half.<ref name="pearsall">Ronald Pearsall, ''Collecting and Restoring Scientific Instruments'', David and Charles, London 1974, {{ISBN|0-7153-6354-9}}</ref>

==See also==
* [[Dollond & Aitchison]]
* [[List of astronomical instrument makers]]

==References==
{{Reflist}}

== External links ==
* {{Commons category-inline}}
* {{cite EB9 |wstitle = John Dollond |volume= VII | page=345| short=1 }}
* [https://books.google.com/books?id=5IIFAAAAQAAJ&pg=PA733 "An account of some experiments concerning the different refrangibility of light"], [[Philosophical Transactions of the Royal Society|''Phil. Trans.'']], {{nobr|vol. 50}}, 1759, {{nobr|p. 733}}

{{Copley Medallists 1751-1800}}

{{Authority control}}

{{DEFAULTSORT:Dollond, John}}
[[Category:1706 births]]
[[Category:1761 deaths]]
[[Category:People from Spitalfields]]
[[Category:18th-century English astronomers]]
[[Category:Recipients of the Copley Medal]]
[[Category:Lens designers]]
[[Category:Fellows of the Royal Society]]
[[Category:English scientific instrument makers]]