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{{Short description|Serbian-American engineer and inventor (1856–1943)}}
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{{Infobox engineer
| native_name = {{nobold|{{lang|sr|Никола Тесла}}}}
| native_name_lang = sr
| image = Tesla circa 1890.jpeg
| alt = Head-and-shoulder photograph of a slender man with dark hair and moustache, dark suit and white-collar shirt
| caption = Tesla, {{circa|1890}}
| birth_date = {{birth date|1856|7|10|df=y}}
| birth_place = [[Smiljan, Croatia|Smiljan]], [[Austrian Empire]]<!-- There is consensus against adding [[Croatian Military Frontier]] here -->
| death_date = {{death date and age|1943|1|7|1856|7|10|df=y}}
| death_place = [[New York City]], U.S.
| resting_place = [[Nikola Tesla Museum]], Belgrade, Serbia
| citizenship = {{ubl
  | Austria (until 1891)
  | U.S. (from 1891)
  }}
| education = [[Graz University of Technology]] (dropped out)
| occupation = {{hlist|Engineer|[[futurist]]|inventor}}
| known_for = 
| awards = {{ubil
  | [[Order of St. Sava]] (1892)
  | [[Elliott Cresson Medal]] (1894)
  | [[Order of Prince Danilo I]] (1895)
  | [[AIEE Edison Medal]] (1916)
   | [[Order of the Yugoslav Crown]] (1931)
  | [[John Scott Medal]] (1934)
  | [[Order of the White Eagle (Serbia)|Order of the White Eagle]] (1937)
  | [[Order of the White Lion]] (1937)
  }}
| discipline =  {{ubl
  | [[Electrical engineering]]
  | [[Mechanical engineering]]}}
| employer =
| significant_design   = [[Induction motor]]
| significant_projects = [[Wireless power transfer]]
| significant_advance  = [[Polyphase system|Polyphase electric power]]
| signature = Nikola Tesla signature 1900.svg
}}
'''Nikola Tesla'''{{efn|{{IPAc-en|lang|ˈ|n|ɪ|k|ə|l|ə|_|ˈ|t|ɛ|s|l|ə}};<ref name="Webster's">[https://www.dictionary.com/browse/tesla "Tesla"] {{Webarchive|url=https://web.archive.org/web/20211024010805/https://www.dictionary.com/browse/tesla |date=24 October 2021 }}. ''[[Random House Webster's Unabridged Dictionary]]''.</ref> {{Lang-sr-Cyrl|Никола Тесла}}; {{IPA|sh|nǐkola têsla|pron}}}} (10 July 1856&nbsp;– 7 January 1943) was a<!-- PLEASE DO NOT CHANGE NATIONALITY OR ETHNICITY--> Serbian-American<!--  SEE Talk:Nikola Tesla/Nationality and ethnicity --> engineer, [[futurist]], and inventor. He is known for his contributions to the design of the modern [[alternating current]] (AC) [[electricity supply]] system.<ref>{{cite book |last=Laplante |first=Phillip A. |url=https://books.google.com/books?id=soSsLATmZnkC |title=Comprehensive Dictionary of Electrical Engineering 1999 |page=635 |publisher=Springer |year=1999 |isbn=978-3-540-64835-2 }}</ref>

Born and raised in the [[Austrian Empire]], Tesla first studied engineering and physics in the 1870s without receiving a degree. He then gained practical experience in the early 1880s working in [[telephony]] and at [[Continental Edison]] in the new [[electric power industry]]. In 1884, he immigrated to the United States, where he became a [[naturalized citizen]]. He worked for a short time at the [[Edison Machine Works]] in New York City before he struck out on his own. With the help of partners to finance and market his ideas, Tesla set up laboratories and companies in New York to develop a range of electrical and mechanical devices. His AC [[induction motor]] and related [[polyphase system|polyphase]] AC patents, licensed by [[Westinghouse Electric Corporation|Westinghouse Electric]] in 1888, earned him a considerable amount of money and became the cornerstone of the polyphase system, which that company eventually marketed.

Attempting to develop inventions he could patent and market, Tesla conducted a range of experiments with mechanical [[Oscillation|oscillators]]/generators, [[Electric discharge|electrical discharge]] tubes, and early [[X-Ray imaging|X-ray imaging]]. He also built a [[wireless]]ly controlled boat, one of the first ever exhibited. Tesla became well known as an inventor and demonstrated his achievements to celebrities and wealthy patrons at his lab, and was noted for his showmanship at public lectures. Throughout the 1890s, Tesla pursued his ideas for wireless lighting and worldwide wireless electric power distribution in his high-voltage, high-frequency power experiments in New York and [[Colorado Springs, Colorado|Colorado Springs]]. In 1893, he made pronouncements on the possibility of [[wireless communication]] with his devices. Tesla tried to put these ideas to practical use in his unfinished [[Wardenclyffe Tower]] project, an intercontinental wireless communication and power transmitter, but ran out of funding before he could complete it.

After Wardenclyffe, Tesla experimented with a series of inventions in the 1910s and 1920s with varying degrees of success. Having spent most of his money, Tesla lived in a series of New York hotels, leaving behind unpaid bills. He died in New York City in January 1943.<ref>{{cite book|last=O'Shei|first=Tim|title=Marconi and Tesla: Pioneers of Radio Communication|year=2008|publisher=MyReportLinks.com Books|isbn=978-1-59845-076-7|page=106}}</ref> Tesla's work fell into relative obscurity following his death, until 1960, when the [[General Conference on Weights and Measures]] named the [[International System of Units]] (SI) measurement of [[magnetic flux density]] the [[tesla (unit)|tesla]] in his honor. There has been a resurgence in popular interest in Tesla since the 1990s.<ref>{{harvnb|Van Riper|2011|p=150}}</ref> In 2013, [[Time magazine|''Time'']] named Tesla one of the 100 most significant figures of all time.<ref>{{Cite magazine |last1=Skiena |first1=Steven |last2=Ward |first2=Charles B. |date=10 December 2013 |title=Who's Biggest? The 100 Most Significant Figures in History |url=https://ideas.time.com/2013/12/10/whos-biggest-the-100-most-significant-figures-in-history/ |access-date=17 June 2025 |magazine=Time |language=en-US |issn=0040-781X}}</ref>

==Early years<span class="anchor" id="Parents"></span>==
<!--"Milutin Tesla" and "Đuka Mandić" redirect here.-->

=== Childhood ===
[[File:Nikola Tesla Memorial Center.JPG|thumb|left|Tesla's rebuilt birth house (parish hall) and the church where his father served in [[Smiljan, Croatia]]. The site was made into [[Nikola Tesla Memorial Center|a museum to honor him]].<ref name="tsbirthplace">{{cite web |title=Pictures of Tesla's home in Smiljan, Croatia and his father's church after rebuilding. |url=http://www.teslasociety.com/birthplace.htm |access-date=22 May 2013 |publisher=Tesla Memorial Society of NY |archive-date=2 June 2003 |archive-url=https://web.archive.org/web/20030602202049/http://www.teslasociety.com/birthplace.htm |url-status=live }}</ref>]]

Nikola Tesla was born on 10 July 1856 in the village of [[Smiljan, Croatia|Smiljan]], in the [[Military Frontier]] of the [[Austrian Empire]] (present-day [[Croatia]]) into an ethnic [[Serbs|Serb]] family.{{sfn|Cheney|Uth|Glenn|1999|p=143}}{{sfn|O'Neill|1944|pp=9, 12}} His father, Milutin Tesla (1819–1879), was a priest of the [[Eastern Orthodox Church]].{{sfn|Dommermuth-Costa|1994|p=12|loc="Milutin, Nikola's father, was a well-educated priest of the Serbian Orthodox Church."}}{{sfn|Carlson|2013|p=14|loc="Following a reprimand at school for not keeping his brass buttons polished, he quit and instead chose to become a priest in the Serbian Orthodox Church"}} His father's brother Josif was a lecturer at a military academy who wrote several textbooks on mathematics.{{sfn|Carlson|2013|page=14}}

Tesla's mother, Georgina "Đuka" Mandić (1822–1892), whose father was also an Eastern Orthodox priest,{{sfn|O'Neill|1944|p=10}} had a talent for making home craft tools and mechanical appliances and the ability to memorize [[Serbian epic poetry|Serbian epic poems]]. Đuka had never received a formal education. Tesla credited his [[eidetic memory]] and creative abilities to his mother's genetics and influence.{{sfn|Cheney|2001|pp=25-26}}{{sfn|Seifer|2001|p=7}}

Tesla was the fourth of five children.{{sfn|Carlson|2013|p=21}} In 1861, Tesla attended primary school in Smiljan where he studied German, arithmetic, and religion. In 1862, the Tesla family moved to the nearby town of [[Gospić]], where Tesla's father worked as parish priest. Nikola completed primary school, followed by middle school. Later in his patent applications, before he obtained American citizenship, Tesla would identify himself as "of Smiljan, [[Lika]], border country of [[Austria-Hungary]]".{{sfn|Wohinz|2019|pp=14–15}}

=== Education ===
[[File:Milutin Tesla.jpg|thumb|upright=.7|Tesla's father, Milutin, was an [[Eastern Orthodox Church|Orthodox]] priest in the village of Smiljan.|left]]
In 1870, Tesla moved to [[Karlovac]]{{sfn|Seifer|2001|p=13}} to attend high school at the [[Gymnasium Karlovac|Higher Real Gymnasium]] where the classes were held in German, as it was usual throughout schools within the Austro-Hungarian Military Frontier.<ref>{{cite book|last1=Tesla|first1=Nikola|last2=Marinčić|first2=Aleksandar|title=From Colorado Springs to Long Island: research notes |date=2008|publisher=Nikola Tesla Museum|location=Belgrade|isbn=978-86-81243-44-2}}</ref><ref>{{cite book |last1=Budiansky |first1=Stephen |title=Journey to the edge of reason : the life of Kurt Gödel |date=2021 |location=New York |isbn=978-1-324-00545-2 |edition=First |quote=In the natural sciences, Austria produced a remarkable number of talented theorists and experimentalists. The electrical genius Nikola Tesla, from Croatia, studied in Karlovac at one of the rigorous German-language high schools, the Gymnasiums, established throughout the Austrian Empire.}}</ref> Tesla later wrote that he became interested in his physics professor's demonstrations of electricity.{{efn|Tesla does not mention which professor this was by name, but some sources conclude this was [[Martin Sekulić]].{{sfn|Seifer|1998|loc=Childhood 1856-74}}{{sfn|Petešić|1976|pp=29–30}}}} The "mysterious phenomena" made him want "to know more of this wonderful force".{{sfn|Carlson|2013|p=32}} He was able to perform [[integral|integral calculus]] in his head, prompting his teachers to believe that he was cheating.<ref>{{cite web |title=Tesla Life and Legacy&nbsp;– Tesla's Early Years |url=https://www.pbs.org/tesla/ll/ll_early.html|publisher=PBS |access-date=8 July 2012 |archive-date=20 July 2018 |archive-url=https://web.archive.org/web/20180720022706/http://www.pbs.org/tesla/ll/ll_early.html |url-status=live}}</ref> He finished a four-year term in three years, graduating in 1873.{{sfn|O'Neill|1944|p=33}}

After graduating Tesla returned to Smiljan but soon contracted [[cholera]], was bedridden for nine months and was near death several times. In a moment of despair, Tesla's father (who had originally wanted him to enter the priesthood),<ref>{{cite book|editor-last=Glenn|editor-first=Jim|title=The complete patents of Nikola Tesla|year=1994|publisher=Barnes & Noble Books|location=New York|isbn=1-56619-266-8|url=https://archive.org/details/completepatentso00tesl}}</ref> promised to send him to the best engineering school if he recovered from the illness.{{sfn|Carlson|2013|p=29}} Tesla later said that he had read [[Mark Twain]]'s earlier works while recovering from his illness.<ref>{{cite news |first=Juliana |last=Adelman |title=The electricity between Mark Twain and Nikola Tesla |url=https://www.irishtimes.com/news/science/the-electricity-between-mark-twain-and-nikola-tesla-1.2522523 |newspaper=The Irish Times |date=11 February 2016}}</ref>

The next year Tesla evaded [[conscription]] into the [[Austro-Hungarian Army]] in Smiljan{{sfn|Seifer|2001|p=14}} by running away southeast of Lika to [[Tomingaj]], near [[Gračac]]. There he explored the mountains wearing hunter's garb. Tesla said that this contact with nature made him stronger, both physically and mentally. He enrolled at the [[Imperial-Royal Technical College in Graz]] in 1875 on a Military Frontier scholarship. Tesla passed nine exams (nearly twice as many as required{{sfn|O'Neill|1944|p=39}}) and received a letter of commendation from the dean of the technical faculty to his father, which stated, "Your son is a star of first rank."{{sfn|O'Neill|1944|p=39}} At Graz, Tesla was fascinated by the lectures on electricity presented by professor [[Jakob Pöschl]].{{sfn|Carlson|2013|pp=35}} But by his third year he was failing in school and never graduated, leaving [[Graz]] in December 1878. One biographer suggests Tesla was not studying and may have been expelled for gambling and womanizing.{{sfn|Seifer|2001|p=17}}

[[File:Tesla 1879 teslauniverse.jpg|thumb|upright=0.75|Tesla aged 23, {{circa|1879}}]]

Tesla's family did not hear from him after he left school.{{sfn|Seifer|2001|pp=17–18}} There was a rumor among his classmates that he had drowned in the nearby river [[Mur (river)|Mur]] but in January one of them ran into Tesla in the town of [[Maribor]] and reported that encounter to Tesla's family.{{sfn|Carlson|2013|pp=47}} It turned out Tesla had been working there as a draftsman for 60 florins per month.{{sfn|Seifer|2001|p=17}} In March 1879, Milutin finally located his son and tried to convince him to return home and take up his education in Prague.{{sfn|Carlson|2013|pp=47}} Tesla returned to Gospić later that month when he was deported for not having a residence permit.{{sfn|Carlson|2013|pp=47}} Tesla's father died the next month, on 17 April 1879, at the age of 60 after an unspecified illness.{{sfn|Carlson|2013|pp=47}}

In January 1880, two of Tesla's uncles paid for him to leave Gospić for [[Prague]], where he was to study. He arrived too late to enroll at [[Charles University|Charles-Ferdinand University]]; he had never studied [[Greek language|Greek]], a required subject; and he was illiterate in [[Czech (language)|Czech]], another required subject. He attended lectures in philosophy at the university as an auditor, but he did not receive grades for the courses.<ref>{{cite book|last=Mrkich|first=D.|title=Nikola Tesla: The European Years|year=2003|publisher=Commoner's Publishing|location=Ottawa|isbn=0-88970-113-X|edition=1st}}</ref><ref>{{cite web|title=Hotel New Yorker in Manhattan pays tribute to Nikola Tesla|url=http://www.teslasociety.com/nyhotel.htm|publisher=Tesla Society of New York|access-date=17 August 2012|archive-date=31 December 2018|archive-url=https://web.archive.org/web/20181231231421/http://www.teslasociety.com/nyhotel.htm|url-status=live}}</ref>

=== Budapest Telephone Exchange ===
Tesla moved to [[Budapest]], [[Lands of the Crown of Saint Stephen|Hungary]], in 1881 to work under [[Tivadar Puskás]] at a [[Telegraphy|telegraph]] company, the Budapest Telephone Exchange. Upon arrival, Tesla realized that the company, then under construction, was not functional, so he worked as a draftsman in the Central Telegraph Office instead. Within a few months, the Budapest Telephone Exchange became functional, and Tesla was allocated the chief electrician position. Tesla later described how he made many improvements to the Central Station equipment including an improved telephone [[repeater]] or [[amplifier]].{{sfn|Carlson|2013|p=63}}

== Working at Edison ==
In 1882, Tivadar Puskás got Tesla another job in Paris with the Continental Edison Company.<ref>{{cite web |url=https://topdocumentaryfilms.com/nikola-tesla-the-genius/ |title=Nikola Tesla: The Genius Who Lit the World |publisher=Top Documentary Films |access-date=24 October 2021 |archive-date=26 April 2019 |archive-url=https://web.archive.org/web/20190426020752/https://topdocumentaryfilms.com/nikola-tesla-the-genius/ |url-status=live }}</ref> Tesla began working in what was then a brand new industry, installing indoor incandescent lighting citywide in large scale electric power [[utility]]. The company had several subdivisions and Tesla worked at the Société Electrique Edison, the division in the [[Ivry-sur-Seine]] suburb of Paris in charge of installing the lighting system. There he gained a great deal of practical experience in electrical engineering. Management took notice of his advanced knowledge in engineering and physics and soon had him designing and building improved versions of generating [[dynamo]]s and motors.{{sfn|Carlson|2013|pp=63–64}} 

=== Moving to the United States ===
[[File:Edison machine works goerck street new york 1881.png|thumb|Edison Machine Works on Goerck Street, New York. Tesla found the change from cosmopolitan Europe to working at this shop, located among the [[tenement]]s on Manhattan's lower east side, a "painful surprise".{{sfn|Carlson|2013|p=70}}]]

In 1884, Edison manager [[Charles Batchelor]], who had been overseeing the Paris installation, was brought back to the United States to manage the [[Edison Machine Works]], a manufacturing division situated in New York City, and asked that Tesla be brought to the United States as well.{{sfn|Carlson|2013|p=69}} In June 1884, Tesla emigrated{{sfn|O'Neill|1944|pp=57–60}} and began working almost immediately at the Machine Works on [[Manhattan]]'s [[Lower East Side]], an overcrowded shop with a workforce of several hundred machinists, laborers, managing staff, and 20 "field engineers" struggling with the task of building the large electric utility in that city.<ref name="edison.rutgers.edu tesla">{{cite web|url=http://edison.rutgers.edu/tesla.htm|title=Edison & Tesla – The Edison Papers|website=edison.rutgers.edu|access-date=23 January 2017|archive-date=11 March 2019|archive-url=https://web.archive.org/web/20190311214910/http://edison.rutgers.edu/tesla.htm|url-status=live}}</ref> As in Paris, Tesla was working on troubleshooting installations and improving generators.<ref>{{cite book |title=American inventors, entrepreneurs & business visionaries |last=Carey |first=Charles W. |year=1989 |publisher=Infobase Publishing |isbn=0-8160-4559-3 |page=337 |url=https://books.google.com/books?id=XKiGgl36bkgC |access-date=27 November 2010 |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323123046/https://books.google.com/books?id=XKiGgl36bkgC |url-status=live }}</ref> 

Historian W. Bernard Carlson notes Tesla may have met company founder [[Thomas Edison]] only a couple of times.<ref name="edison.rutgers.edu tesla" /> One of those times was noted in Tesla's autobiography where, after staying up all night repairing the damaged dynamos on the ocean liner {{SS|Oregon|1883|6}}, he ran into Batchelor and Edison, who made a quip about their "Parisian" being out all night. After Tesla told them he had been up all night fixing the ''Oregon'', Edison commented to Batchelor that "this is a damned good man".{{sfn|Carlson|2013|p=70}} One of the projects given to Tesla was to develop an [[arc lamp]]–based street lighting system.{{sfn|Carlson|2013|pp=71–73}}<ref name="Notebook">[https://teslauniverse.com/nikola-tesla/books/nikola-tesla-notebook-edison-machine-works-1884-1885 Radmilo Ivanković' Dragan Petrović, review of the reprinted "Nikola Tesla: Notebook from the Edison Machine Works 1884–1885"] {{Webarchive|url=https://web.archive.org/web/20190226120239/https://teslauniverse.com/nikola-tesla/books/nikola-tesla-notebook-edison-machine-works-1884-1885 |date=26 February 2019 }} {{ISBN|86-81243-11-X}}, teslauniverse.com</ref> Arc lighting was the most popular type of street lighting but it required high voltages and was incompatible with the Edison low-voltage incandescent system, causing the company to lose contracts in some cities. Tesla's designs were never put into production, possibly because of technical improvements in incandescent street lighting or because of an installation deal that Edison made with an arc lighting company.{{sfn|Carlson|2013|pp=72–73}}

Tesla had been working at the Machine Works for a total of six months when he quit.<ref name="edison.rutgers.edu tesla" /> What event precipitated his leaving is unclear. It may have been over a bonus he did not receive, either for redesigning generators or for the arc lighting system that was shelved.{{sfn|Carlson|2013|pp=71–73}} Tesla had previous run-ins with the Edison company over unpaid bonuses he believed he had earned.{{sfn|Seifer|2001|pp=25, 34}}{{sfn|Carlson|2013|pp=69–73}} In his autobiography, Tesla stated the manager of the Edison Machine Works offered a $50,000 bonus to design "twenty-four different types of standard machines" "but it turned out to be a practical joke".<ref name="Autobiography-1919">[[#Autobiography|''My Inventions: The Autobiography of Nikola Tesla'', 1919]], p. 19. Accessed 23 January 2017.</ref> Later versions of this story have Thomas Edison himself offering and then reneging on the deal, quipping: "Tesla, you don't understand our American humor".{{sfn|O'Neill|1944|p=64}}<ref>{{harvnb|Pickover|1999|p=14}}</ref> The size of the bonus in either story has been noted as odd, since Machine Works manager Batchelor was stingy with pay,{{efn|Tesla's contemporaries remembered that on a previous occasion Machine Works manager Batchelor had been unwilling to give Tesla a $7 a week pay raise<ref>Seifer – ''Wizard: The Life and Times of Nikola Tesla'', p. 38</ref>}} and the company did not have that amount of cash (equal to ${{Inflation|US|50000|1884|fmt=c}} today) on hand.{{sfn|Jonnes|2004|pp=109–110}}{{sfn|Seifer|2001|p=38}} Tesla's diary contains just one comment on what happened at the end of his employment, a note he scrawled across the two pages covering 7 December 1884, to 4 January 1885, saying "Good By to the Edison Machine Works".<ref name="Notebook" />{{sfn|Carlson|2013|p=73}}

== Tesla Electric Light and Manufacturing ==
Soon after leaving the Edison company, Tesla was working on patenting an arc lighting system,{{sfn|Jonnes|2004|pp=110–111}} possibly the same one he had developed at Edison.<ref name="edison.rutgers.edu tesla" /> In March 1885, he met with patent attorney Lemuel W. Serrell, the same attorney used by Edison, to obtain help with submitting the patents.{{sfn|Jonnes|2004|pp=110–111}} Serrell introduced Tesla to two businessmen, Robert Lane and Benjamin Vail, who agreed to finance an arc lighting manufacturing and utility company in Tesla's name, the [[Tesla Electric Light & Manufacturing|Tesla Electric Light and Manufacturing Company]].{{sfn|Seifer|1998|p=41}} Tesla worked for the rest of the year obtaining the patents that included an improved DC generator, the first patents issued to Tesla in the US, and building and installing the system in [[Rahway, New Jersey|Rahway]], New Jersey.{{sfn|Jonnes|2004|p=111}} 

The investors showed little interest in Tesla's ideas for new types of [[alternating current]] motors and electrical transmission equipment. After the utility was up and running in 1886, they decided that the manufacturing side of the business was too competitive and opted to simply run an electric utility.{{sfn|Carlson|2013|p=75}} They formed a new utility company, abandoning Tesla's company and leaving the inventor penniless.{{sfn|Carlson|2013|p=75}} Tesla even lost control of the patents he had generated, since he had assigned them to the company in exchange for stock.{{sfn|Carlson|2013|p=75}} He had to work at various electrical repair jobs and as a ditch digger for $2 per day. Later in life, Tesla recounted that part of 1886 as a time of hardship, writing "My high education in various branches of science, mechanics and literature seemed to me like a mockery".{{sfn|Carlson|2013|p=75}}{{efn|Account comes from a letter Tesla sent in 1938 on the occasion of receiving an award from the National Institute of Immigrant Welfare<ref>{{cite book | editor-first = John T. | editor-last = Ratzlaff | title = Tesla Said | publisher = Tesla Book Co. | location = Millbrae, California | page = 280 | year = 1984 | isbn = 0-914119-00-1 | url = https://archive.org/details/nikolateslajohnt.ratzlaffteslasaid }}</ref>}}

== AC and the induction motor ==
[[File:RMFpatent.PNG|thumb|upright|Drawing from {{US patent|381,968}}, illustrating the principle of Tesla's alternating current induction motor]]

In late 1886, Tesla met Alfred S. Brown, a [[Western Union]] superintendent, and New York attorney Charles Fletcher Peck.<ref>Charles Fletcher Peck of [[Englewood, New Jersey]] per [https://patents.google.com/patent/US381968A/en] {{Webarchive|url=https://web.archive.org/web/20201008142341/https://patents.google.com/patent/US381968A/en|date=8 October 2020}}</ref> The two men were experienced in setting up companies and promoting inventions and patents for financial gain.{{sfn|Carlson|2013|p=80}} Based on Tesla's new ideas for electrical equipment, including a [[thermo-magnetic motor]] idea,{{sfn|Carlson|2013|pp=76–78}} they agreed to back the inventor financially and handle his patents. Together they formed the Tesla Electric Company in April 1887, with an agreement that profits from generated patents would go {{frac|1|3}} to Tesla, {{frac|1|3}} to Peck and Brown, and {{frac|1|3}} to fund development.{{sfn|Carlson|2013|p=80}} They set up a laboratory for Tesla at 89 Liberty Street in Manhattan, where he worked on improving and developing new types of electric motors, generators, and other devices.<ref>{{cite web |last=Carlson |first=W. Bernard |title=Places of Invention: Nikola Tesla's Life in New York |url=https://www.gothamcenter.org/blog/places-of-invention-nikola-teslas-life-in-new-york |publisher=The Gotham Center for New York City History |access-date=15 July 2025 |location=Manhattan |date=14 June 2013 |ref={{harvid|Gotham Center|2013}} }}</ref>

In 1887, Tesla developed an [[induction motor]] that ran on alternating current (AC), a power system format that was rapidly expanding in Europe and the United States because of its advantages in long-distance, [[high-voltage]] transmission. The motor used [[Polyphase system|polyphase]] current, which generated a [[rotating magnetic field]] to turn the motor (a principle that Tesla claimed to have conceived in 1882).<ref name="ReferenceB">{{cite book |title=Networks of Power: Electrification in Western Society, 1880–1930 |publisher=JHU Press |page=117 |url=https://books.google.com/books?id=g07Q9M4agp4C&pg=PA117 |isbn=978-0-8018-4614-4 |date=March 1993 |access-date=13 December 2015 |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323123125/https://books.google.com/books?id=g07Q9M4agp4C&pg=PA117#v=onepage&q&f=false |url-status=live }}</ref><ref>Thomas Parke Hughes, ''Networks of Power: Electrification in Western Society, 1880–1930'', pp. 115–118</ref><ref>{{cite book |url=https://books.google.com/books?id=1AsFdUxOwu8C&pg=PA204 |title=Robert Bud, Instruments of Science: An Historical Encyclopedia |page=204 |access-date=18 March 2013 |isbn=978-0-8153-1561-2 |last1=Ltd |first1=Nmsi Trading |last2=Institution |first2=Smithsonian |year=1998 |publisher=Taylor & Francis |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323123051/https://books.google.com/books?id=1AsFdUxOwu8C&pg=PA204#v=onepage&q&f=false |url-status=live }}</ref> This innovative electric motor, patented in May 1888, was a simple self-starting design that did not need a [[Commutator (electric)|commutator]], thus avoiding sparking and the high maintenance of constantly servicing and replacing mechanical brushes.{{sfn|Jonnes|2004|p=161}}<ref>Henry G. Prout, ''A Life of George Westinghouse'', p. 129</ref>

Along with getting the motor patented, Peck and Brown arranged to get the motor publicized, starting with independent testing to verify it was a functional improvement, followed by press releases sent to technical publications for articles to run concurrently with the issue of the patent.{{sfn|Carlson|2013|p=105-106}} Physicist [[William Arnold Anthony]] (who tested the motor) and ''Electrical World'' magazine editor [[Thomas Commerford Martin]] arranged for Tesla to demonstrate his AC motor on 16 May 1888 at the [[American Institute of Electrical Engineers]].{{sfn|Carlson|2013|p=105-106}}<ref>{{cite book |url=https://books.google.com/books?id=8j5bJ5OkGpgC&pg=PA36 |first1=Fritz E. |last1=Froehlich |first2=Allen |last2=Kent |author-link2=Allen Kent |title=The Froehlich/Kent Encyclopedia of Telecommunications: Volume 17 |page=36 |access-date=10 September 2012 |isbn=978-0-8247-2915-8 |date=December 1998 |publisher=CRC Press |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323123231/https://books.google.com/books?id=8j5bJ5OkGpgC&pg=PA36#v=onepage&q&f=false |url-status=live }}</ref> Engineers working for the [[Westinghouse Electric Corporation|Westinghouse Electric & Manufacturing Company]] reported to [[George Westinghouse]] that Tesla had a viable AC motor and related power system—something Westinghouse needed for the alternating current system he was already marketing. Westinghouse looked into getting a patent on a similar commutator-less, rotating magnetic field-based induction motor developed in 1885 and presented in a paper in March 1888 by Italian physicist [[Galileo Ferraris]], but decided that Tesla's patent would probably control the market.{{sfn|Jonnes|2004|p=160–162}}{{sfn|Carlson|2013|pp=108–111}}

[[File:US390721.png|thumb|right|upright|Tesla's AC dynamo-electric machine (AC [[electric generator]]) in an 1888 {{US patent|390721}}]]

In July 1888, Brown and Peck negotiated a licensing deal with George Westinghouse for Tesla's polyphase induction motor and transformer designs for $60,000 in cash and stock and a royalty of $2.50 per AC horsepower produced by each motor. Westinghouse also hired Tesla for one year for the large fee of $2,000 (${{Inflation|US|2000|1888|r=-2|fmt=c}} in today's dollars{{Inflation-fn|US}}) per month to be a consultant at the Westinghouse Electric & Manufacturing Company's [[Pittsburgh]] labs.{{sfn|Klooster|2009|p=305}}

During that year, Tesla worked in Pittsburgh, helping to create an alternating current system to power the city's streetcars. He found it a frustrating period because of conflicts with the other Westinghouse engineers over how best to implement AC power. Between them, they settled on a 60-cycle AC system that Tesla proposed (to match the working frequency of Tesla's motor), but they soon found that it would not work for streetcars, since Tesla's induction motor could run only at a constant speed. They ended up using a DC [[traction motor]] instead.<ref>{{cite web|last=Harris|first=William|url=https://science.howstuffworks.com/nikola-tesla.htm#pt2|title=William Harris, How did Nikola Tesla change the way we use energy?|page=3|publisher=Science.howstuffworks.com|date=14 July 2008|access-date=10 September 2012|archive-date=22 May 2019|archive-url=https://web.archive.org/web/20190522131016/https://science.howstuffworks.com/nikola-tesla2.htm#pt2|url-status=live}}</ref><ref name=Munson>{{cite book|title=From Edison to Enron: The Business of Power and What It Means for the Future of Electricity|publisher=Praeger|last=Munson |first=Richard|year=2005|pages=[https://archive.org/details/fromedisontoenro00muns_0/page/24 24–42]|location=Westport, CT|isbn=978-0-275-98740-4|url=https://archive.org/details/fromedisontoenro00muns_0/page/24}}</ref>

=== Market turmoil ===
Tesla's demonstration of his induction motor and Westinghouse's subsequent licensing of the patent, both in 1888, came at the time of extreme competition between electric companies.{{sfn|Skrabec|2007|p=119–121}}<ref>Robert L. Bradley, Jr. (2011). ''Edison to Enron: Energy Markets and Political Strategies'', John Wiley & Sons, pp. 55–58</ref> The three big firms, Westinghouse, Edison, and [[Thomson-Houston Electric Company]], were trying to grow in a capital-intensive business while financially undercutting each other. There was even a "[[war of currents]]" propaganda campaign going on, with Edison Electric claiming their [[direct current]] system was better and safer than the Westinghouse alternating current system and Thomson-Houston sometimes siding with Edison.{{sfn|Skrabec|2007|p=118–120}}{{sfn|Seifer|1998|p=47}} Competing in this market meant Westinghouse would not have the cash or engineering resources to develop Tesla's motor and the related polyphase system right away.{{sfn|Skrabec|2007|p=}}

Two years after signing the Tesla contract, Westinghouse Electric was in trouble. The near collapse of [[Barings Bank]] in London triggered the [[Panic of 1890|financial panic of 1890]], causing investors to call in their loans to Westinghouse Electric.{{sfn|Carlson|2013|p=130}} The sudden cash shortage forced the company to refinance its debts. The new lenders demanded that Westinghouse cut back on what looked like excessive spending on acquisition of other companies, research, and patents, including the per motor royalty in the Tesla contract.{{sfn|Carlson|2013|p=131}}{{sfn|Jonnes|2004|p=29}} At that point, the Tesla induction motor had been unsuccessful and was stuck in development.{{sfn|Skrabec|2007|p=}}{{sfn|Carlson|2013|p=130}} Westinghouse was paying a $15,000-a-year guaranteed royalty<ref>Thomas Parke Hughes, ''Networks of Power: Electrification in Western Society, 1880–1930'' (1983), p. 119</ref> even though operating examples of the motor were rare and polyphase power systems needed to run it were even rarer.{{sfn|Jonnes|2004|p=161}}{{sfn|Carlson|2013|p=130}} 

In early 1891, George Westinghouse explained his financial difficulties to Tesla in stark terms, saying that, if he did not meet the demands of his lenders, he would no longer be in control of Westinghouse Electric and Tesla would have to "deal with the bankers" to try to collect future royalties.{{sfn|Jonnes|2004|p=228}} The advantages of having Westinghouse continue to champion the motor probably seemed obvious to Tesla and he agreed to release the company from the royalty payment clause in the contract.{{sfn|Jonnes|2004|p=228}}{{sfn|Carlson|2013|pp=130–131}} Six years later Westinghouse purchased Tesla's patent for a [[lump sum]] payment of $216,000 as part of a patent-sharing agreement signed with [[General Electric]] (a company created from the 1892 merger of Edison and Thomson-Houston).{{sfn|Cheney|2001|pp=48–49}}<ref>Christopher Cooper, ''The Truth about Tesla: The Myth of the Lone Genius in the History of Innovation'', Race Point Publishing. 2015, p. 109</ref><ref>''Electricity, a Popular Electrical Journal'', Volume 13, No. 4, 4 August 1897, Electricity Newspaper Company, pp. 50 [https://books.google.com/books?id=nNA9AQAAMAAJ&q=tesla+patent+1897+%22patent+pool%22&pg=PA50 Google Books] {{Webarchive|url=https://web.archive.org/web/20230528024213/https://books.google.com/books?id=nNA9AQAAMAAJ&q=tesla+patent+1897+%22patent+pool%22&pg=PA50 |date=28 May 2023 }}</ref>

== New York laboratories ==
[[File:Twain in Tesla's Lab.jpg|thumb|alt=Mark Twain in Tesla's lab, 1894|[[Mark Twain]] in Tesla's South Fifth Avenue laboratory, 1894]]

The money Tesla made from licensing his AC patents made him [[independently wealthy]] and gave him the time and funds to pursue his own interests.<ref>{{cite journal | url = https://teslauniverse.com/nikola-tesla/articles/nikola-tesla-scientific-savant | title = Nikola Tesla: Scientific Savant from the Tesla Universe Article Collection | first = James P. |last = Rybak | journal = [[Popular Electronics]] | date = November 1999 | pages = 40–48 & 88 | access-date = 21 January 2017 | archive-date = 26 February 2019 | archive-url = https://web.archive.org/web/20190226121548/https://teslauniverse.com/nikola-tesla/articles/nikola-tesla-scientific-savant | url-status = live }}</ref> In 1889, Tesla moved out of the Liberty Street shop Peck and Brown had rented and for the next dozen years worked out of a series of workshop/laboratory spaces in Manhattan. These included a lab at 175 [[Grand Street (Manhattan)|Grand Street]] (1889–1892), the fourth floor of 33–35 South [[Fifth Avenue]] (1892–1895), and sixth and seventh floors of 46 & 48 East [[Houston Street]] (1895–1902).<ref>Carlson, W. Bernard (2013). ''Tesla: Inventor of the Electrical Age'', Princeton University Press, p. 218</ref><ref>{{cite web|url=https://teslaresearch.jimdo.com/labs-in-new-york-1889-1902/|title=Laboratories in New York (1889–1902)|website=Open Tesla Research|access-date=21 January 2017|archive-date=20 August 2018|archive-url=https://web.archive.org/web/20180820234947/https://teslaresearch.jimdo.com/labs-in-new-york-1889-1902/|url-status=live}}</ref> 

=== Tesla coil ===
{{main|Tesla coil}}

In the summer of 1889, Tesla traveled to the [[Exposition Universelle (1889)|1889 Exposition Universelle]] in Paris and learned of [[Heinrich Hertz]]'s 1886–1888 experiments that proved the existence of [[electromagnetic radiation]], including [[radio wave]]s.{{sfn|Carlson|2013|p=120}} In repeating and then expanding on these experiments Tesla tried powering a [[Induction coil|Ruhmkorff coil]] with a high speed [[alternator]] he had been developing as part of an improved arc lighting system but found that the high-frequency current overheated the iron core and melted the insulation between the primary and secondary windings in the coil. To fix this problem Tesla came up with his "oscillating transformer", with an air gap instead of insulating material between the primary and secondary windings and an iron core that could be moved to different positions in or out of the coil.{{sfn|Carlson|2013|p=122}} Later called the Tesla coil, it would be used to produce high-[[voltage]], low-[[Electric current|current]], high [[frequency]] alternating-current electricity.<ref name="NMFL">{{cite web |title=Tesla coil |work=Museum of Electricity and Magnetism, Center for Learning |publisher=National High Magnetic Field Laboratory website, Florida State Univ. |date=2011 |url=https://nationalmaglab.org/education/magnet-academy/history-of-electricity-magnetism/museum/tesla-coil-1891 |access-date=12 September 2013 |archive-date=23 September 2015 |archive-url=https://web.archive.org/web/20150923174243/https://nationalmaglab.org/education/magnet-academy/history-of-electricity-magnetism/museum/tesla-coil-1891 |url-status=live }}</ref> He would use this [[resonant transformer|resonant transformer circuit]] in his later wireless power work.{{sfn|Carlson|2013|p=124}}<ref name="BurnettOperation">{{cite web   | last = Burnett  | first = Richie  | title = Operation of the Tesla Coil | work = Richie's Tesla Coil Web Page  | publisher = Richard Burnett private website  | date = 2008  | url = http://www.richieburnett.co.uk/operation.html#operation  | access-date = 24 July 2015 | archive-date = 20 July 2015
| archive-url = https://web.archive.org/web/20150720104724/http://www.richieburnett.co.uk/operation.html#operation | url-status = live }}</ref>

=== Wireless lighting ===
[[File:TeslaWirelessPower1891.png|thumb|right|Tesla demonstrating wireless lighting by "electrostatic induction" during an 1891 lecture at [[Columbia College (New York)|Columbia College]] via two long [[Geissler tube]]s (similar to [[Neon light|neon tubes]]) in his hands]]

After 1890, Tesla experimented with transmitting power by inductive and capacitive coupling using high AC voltages generated with his Tesla coil.<ref name="Tesla1891">{{Cite book |url=http://www.tfcbooks.com/tesla/1891-05-20.htm |title=Experiments with Alternate Currents of Very High Frequency and Their Application to Methods of Artificial Illumination |first=Nikola |last=Tesla |publication-date=20 May 1891 |access-date=21 January 2017 |archive-date=6 March 2023 |archive-url=https://web.archive.org/web/20230306023235/http://www.tfcbooks.com/tesla/1891-05-20.htm |url-status=live }}, lecture delivered before the [[American Institute of Electrical Engineers]], Columbia College, New York. Reprinted as a {{cite book |title = book of the same name by |publisher = Wildside Press |date = 2006 |url = https://books.google.com/books?id=94eH3rULPy4C |isbn = 0-8095-0162-7 |access-date = 21 January 2017 |archive-date = 23 March 2024 |archive-url = https://web.archive.org/web/20240323123047/https://books.google.com/books?id=94eH3rULPy4C |url-status = live }}</ref> He attempted to develop a wireless lighting system based on [[Near and far field|near-field]] inductive and capacitive coupling and conducted a series of public demonstrations where he lit [[Geissler tube]]s and even incandescent light bulbs from across a stage.{{sfn|Carlson|2013|p=132}} He spent most of the decade working on variations of this new form of lighting with the help of various investors but none of the ventures succeeded in making a commercial product out of his findings.<ref>Christopher Cooper (2015). ''The Truth About Tesla: The Myth of the Lone Genius in the History of Innovation'', Race Point Publishing, pp. 143–144</ref>

In 1893 at [[St. Louis]], Missouri, the [[Franklin Institute]] in [[Philadelphia]], Pennsylvania and the [[National Electric Light Association]], Tesla told onlookers that he was sure a system like his could eventually conduct "intelligible signals or perhaps even power to any distance without the use of wires" by conducting it through the Earth.{{sfn|Carlson|2013|pp=178–179}}<ref name="Orton">{{cite book |last=Orton |first=John |title=The Story of Semiconductors |year=2004 |publisher=Oxford University Press |location=Oxford, England |page=53}}</ref>

On 30 July 1891, aged 35, Tesla became a [[naturalized citizen]] of the United States.<ref name="NYcourts">{{Cite web |url=https://www.fold3.com/image/20564444?ann=f3dc7880-a283-11dc-2973-11792d3d4a08 |title=Naturalization Record of Nikola Tesla, 30 July 1891 |access-date=24 October 2021 |archive-date=24 October 2021 |archive-url=https://web.archive.org/web/20211024010806/https://www.fold3.com/image/20564444?ann=f3dc7880-a283-11dc-2973-11792d3d4a08 |url-status=live }}, Naturalization Index, NYC Courts, referenced in Carlson (2013), ''Tesla: Inventor of the Electrical Age'', p. H-41</ref>{{sfn|Carlson|2013|p=138}} In the same year, he patented his Tesla coil.<ref name="Uth">{{cite web|last=Uth|first=Robert|title=Tesla coil|date=12 December 2000|work=Tesla: Master of Lightning|publisher=PBS.org|url=https://www.pbs.org/tesla/ins/lab_tescoil.html|access-date=20 May 2008|archive-date=5 September 2019|archive-url=https://web.archive.org/web/20190905184548/http://www.pbs.org/tesla/ins/lab_tescoil.html|url-status=live}}</ref> 
He served as a vice-president of the American Institute of Electrical Engineers from 1892 to 1894, the forerunner of the modern-day [[Institute of Electrical and Electronics Engineers]] (IEEE) (along with the [[Institute of Radio Engineers]]).<ref>{{cite web|title=Tesla's Connection to Columbia University|url=http://www.teslasociety.com/columbia.pdf|publisher=Tesla Memorial Society of NY|access-date=5 July 2012|first1=Kenneth L.|last1=Corum|first2=James F.|last2=Corum|name-list-style=amp|archive-date=18 November 2017|archive-url=https://web.archive.org/web/20171118002803/http://www.teslasociety.com/columbia.pdf|url-status=live}}</ref>

=== Polyphase system and the Columbian Exposition<span class="anchor" id="The "Tesla Polyphase System""></span> ===

[[File:TeslaPOLYPHASEColumbianEXPO1893rwLIPACKownerA.pdf|thumbnail|A Westinghouse display of the "Tesla Polyphase System" at Chicago's 1893 Columbian Exposition]]

By the beginning of 1893, Westinghouse engineer [[Charles F. Scott (engineer)|Charles F. Scott]] and then [[Benjamin G. Lamme]] had made progress on an efficient version of Tesla's induction motor. Lamme found a way to make the polyphase system it would need compatible with older single-phase AC and DC systems by developing a [[rotary converter]].{{sfn|Carlson|2013|p=166}} Westinghouse Electric now had a way to provide electricity to all potential customers and started branding their polyphase AC system as the "Tesla Polyphase System". They believed that Tesla's patents gave them [[Priority right|patent priority]] over other polyphase AC systems.{{sfn|Carlson|2013|p=167}}

Westinghouse Electric asked Tesla to participate in the 1893 [[World's Columbian Exposition]] in Chicago where the company had a large space in the "Electricity Building" devoted to electrical exhibits. Westinghouse Electric won the bid to light the Exposition with alternating current and it was a key event in the history of AC power, as the company demonstrated to the American public the safety, reliability, and efficiency of an alternating current system that was polyphase and could also supply the other AC and DC exhibits at the fair.<ref>{{cite book |first=Richard |last=Moran |title=Executioner's Current: Thomas Edison, George Westinghouse, and the Invention of the Electric Chair |publisher=Knopf Doubleday Publishing Group |date=2007 |page=222}}</ref><ref>{{cite book |url=https://books.google.com/books?id=-ErxIGp3QN0C |title=America at the Fair: Chicago's 1893 World's Columbian Exposition |first=Chaim M. |last=Rosenberg |publisher=Arcadia Publishing |date=20 February 2008 |isbn=978-0-7385-2521-1 |access-date=3 November 2021 |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323123130/https://books.google.com/books?id=-ErxIGp3QN0C |url-status=live }}</ref><ref>{{cite book|url=https://books.google.com/books?id=F6cWRxU9go4C&pg=PR21|title=The World's Columbian Exposition: A Centennial Bibliographic Guide|first1=David J.|last1=Bertuca|first2=Donald K.|last2=Hartman|first3=Susan M.|last3=Neumeister|year=1996|name-list-style=amp|pages=xxi|publisher=Bloomsbury Academic|isbn=978-0-313-26644-7|access-date=10 September 2012|archive-date=23 March 2024|archive-url=https://web.archive.org/web/20240323123640/https://books.google.com/books?id=F6cWRxU9go4C&pg=PR21|url-status=live}}</ref>

A special exhibit space was set up to display various forms and models of Tesla's induction motor. The rotating magnetic field that drove them was explained through a series of demonstrations including an ''[[Tesla's Egg of Columbus|Egg of Columbus]]'' that used the two-phase coil found in an induction motor to spin a copper egg making it stand on end.<ref>Hugo Gernsback, "Tesla's Egg of Columbus, How Tesla Performed the Feat of Columbus Without Cracking the Egg" Electrical Experimenter, 19 March 1919, p. 774 [http://www.teslacollection.com/tesla_articles/1919/electrical_experimenter/h_gernsback/the_tesla_egg_of_columbus] {{Webarchive|url=https://web.archive.org/web/20200327222415/http://www.teslacollection.com/tesla_articles/1919/electrical_experimenter/h_gernsback/the_tesla_egg_of_columbus|date=27 March 2020}}</ref>

Tesla visited the fair for a week during its six-month run to attend the [[International Electrical Congress]] and put on a series of demonstrations at the Westinghouse exhibit.{{sfn|Seifer|2001|p=120}}<ref>Thomas Commerford Martin, The Inventions, Researches and Writings of Nikola Tesla: With Special Reference to His Work in Polyphase Currents and High Potential Lighting, Electrical Engineer – 1894, Chapter XLII, page 485 [https://archive.org/details/inventionsresear00martiala]</ref> A specially darkened room had been set up where Tesla showed his wireless lighting system, using a demonstration he had previously performed throughout America and Europe;{{sfn|Cheney|2001|p=76}} these included using high-voltage, high-frequency alternating current to light wireless [[gas-discharge lamp]]s.{{sfn|Cheney|2001|p=79}}<ref>{{cite book |title=Electricity at the Columbian Exposition; Including an Account of the Exhibits in the Electricity Building, the Power Plant in Machinery Hall |publisher=R. R. Donnelley |last=Barrett |first=John Patrick |year=1894 |pages=[https://archive.org/details/electricityatco00barrgoog/page/n288 268]–269 |url=https://archive.org/details/electricityatco00barrgoog |access-date=29 November 2010}}</ref>

=== Steam-powered oscillating generator ===
{{main|Tesla's oscillator}}

During his presentation at the International Electrical Congress in the Columbian Exposition Agriculture Hall, Tesla introduced his [[Tesla's oscillator|steam-powered reciprocating electricity generator]] that he patented that year, something he thought was a better way to generate alternating current.{{sfn|Carlson|2013|p=182}} Steam was forced into the oscillator and rushed out through a series of ports, pushing a piston up and down that was attached to an armature. The magnetic armature vibrated up and down at high speed, producing an alternating [[magnetic field]]. This [[electromagnetic induction|induced]] alternating electric current in the wire coils located adjacent. It did away with the complicated parts of a steam engine/generator, but never caught on as a feasible engineering solution to generate electricity.{{sfn|Carlson|2013|pp=181–185}}<ref>Reciprocating Engine, {{US patent|514169}}, 6 February 1894.</ref>

=== Consulting on Niagara ===
In 1893, [[Edward Dean Adams]], who headed the [[Niagara Falls]] [[Cataract Construction Company]], sought Tesla's opinion on what system would be best to transmit power generated at the falls. Over several years, there had been a series of proposals and open competitions on how best to do it. Among the systems proposed by several US and European companies were two-phase and three-phase AC, high-voltage DC, and compressed air. Adams asked Tesla for information about the current state of all the competing systems. Tesla advised Adams that a two-phased system would be the most reliable and that there was a Westinghouse system to light incandescent bulbs using two-phase alternating current. The company awarded a contract to Westinghouse Electric for building a two-phase AC generating system at the Niagara Falls, based on Tesla's advice and Westinghouse's demonstration at the Columbian Exposition. At the same time, a further contract was awarded to General Electric to build the AC distribution system.{{sfn|Carlson|2013|pp=167–173}}

=== The Nikola Tesla Company ===
In 1895, Edward Dean Adams, impressed with what he saw when he toured Tesla's lab, agreed to help found the Nikola Tesla Company, set up to fund, develop, and market a variety of previous Tesla patents and inventions as well as new ones. Alfred Brown signed on, bringing along patents developed under Peck and Brown. The board was filled out with William Birch Rankine and Charles F. Coaney.{{sfn|Carlson|2013|pp=205–206}}

On 13 March 1895, the South Fifth Avenue building that housed Tesla's lab caught fire. It started in the basement of the building and was so intense Tesla's fourth-floor lab burned and collapsed into the second floor. The fire set back Tesla's ongoing projects, and destroyed a collection of early notes and research material, models, and demonstration pieces, including many that had been exhibited at the 1893 Worlds Colombian Exposition. Tesla told ''[[The New York Times]]'' "I am in too much grief to talk. What can I say?".<ref>Mr. Tesla's Great Loss, All of the Electrician's Valuable Instruments Burned, Work of Half a Lifetime Gone, New York Times, 14 March 1895 (archived at [https://teslauniverse.com/nikola-tesla/articles/mr-teslas-great-loss teslauniverse.com] {{Webarchive|url=https://web.archive.org/web/20220628160738/https://teslauniverse.com/nikola-tesla/articles/mr-teslas-great-loss |date=28 June 2022 }})</ref>

=== X-ray experimentation ===
[[File:X-Ray Photograph of Tesla's left hand.jpg|left|thumb|upright|Tesla took this x-ray of his hand.]]

Starting in 1894, Tesla began investigating what he referred to as [[radiant energy]] of "invisible" kinds after he had noticed damaged film in his laboratory in previous experiments<ref>{{cite book|last1=Tesla|first1=Nikola|title=X-ray vision: Nikola Tesla on Roentgen rays|date=2007|publisher=Wiilder Publications|location=Radford, VA|isbn=978-1-934451-92-2|edition=1st}}</ref> (later identified as "Roentgen rays" or "[[X-rays]]"). His early experiments were with [[Crookes tube]]s, a [[cold cathode]] electrical discharge tube. Tesla may have inadvertently captured an X-ray image—predating, by a few weeks, [[Wilhelm Röntgen]]'s December 1895 announcement of the discovery of X-rays—when he tried to photograph Mark Twain illuminated by a Geissler tube, an earlier type of gas discharge tube. The only thing captured in the image was the metal locking screw on the camera lens.{{sfn|Cheney|2001|p=134}}

In March 1896, Tesla conducted experiments in X-ray imaging, developing a high-energy single-terminal [[vacuum tube]] that had no target electrode and that worked from the output of the Tesla coil (the modern term for the phenomenon produced by this device is ''[[bremsstrahlung]]'' or ''braking radiation''). In his research, Tesla devised several experimental setups to produce X-rays. Tesla held that, with his circuits, the "instrument will&nbsp;... enable one to generate Roentgen rays of much greater power than obtainable with ordinary apparatus".<ref>{{cite book |first=Nikola |last=Tesla |url=http://www.tfcbooks.com/tesla/1898-11-17.htm |chapter=High Frequency Oscillators for Electro-Therapeutic and Other Purposes |title=Proceedings of the American Electro-Therapeutic Association |publisher=American Electro-Therapeutic Association |page=25 |date=17 November 1898 |access-date=27 January 2009 |archive-date=1 January 2016 |archive-url=https://web.archive.org/web/20160101011808/http://www.tfcbooks.com/tesla/1898-11-17.htm |url-status=live }}</ref>

Tesla noted the hazards of working with his circuit and single-node X-ray-producing devices. In his many notes on the early investigation of this phenomenon, he attributed the skin damage to various causes. He believed early on that damage to the skin was not caused by the Roentgen rays, but by the [[ozone]] generated in contact with the skin, and to a lesser extent, by [[nitrous acid]]. Tesla incorrectly believed that X-rays were longitudinal waves, such as those produced in [[waves in plasmas]]. These plasma waves can occur in [[force-free magnetic field]]s.<ref>Griffiths, David J. ''Introduction to Electrodynamics'', {{ISBN|0-13-805326-X}} and Jackson, John D. ''Classical Electrodynamics'', {{ISBN|0-471-30932-X}}.</ref><ref>{{cite book |title=Transactions of the American Electro-therapeutic Association |publisher=American Electrotherapeutic Association |year=1899 |page=16 |url=https://books.google.com/books?id=bUo7vYNkbKQC |access-date=25 November 2010 |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323123806/https://books.google.com/books?id=bUo7vYNkbKQC |url-status=live }}</ref>

=== Radio remote control ===
[[File:Tesla boat1.jpg|thumb|upright|In 1898, Tesla demonstrated a radio-controlled boat, which he hoped to sell as a guided torpedo to navies around the world.<ref>W. Bernard Carlson, Tesla: Inventor of the Electrical Age, Princeton University Press – 2013, p.&nbsp;231.</ref>]]

In 1898, Tesla demonstrated a boat that used a [[coherer]]-based [[radio control]]—which he dubbed "telautomaton"—to the public during an electrical exhibition at [[Madison Square Garden (1890)|Madison Square Garden]].{{sfn|Jonnes|2004}} Tesla tried to sell his idea to the US military as a type of radio-controlled [[torpedo]], but they showed little interest.<ref>{{cite book |url=https://books.google.com/books?id=6aStP3Du5cgC&pg=PT50 |first=P. W. |last=Singer |title=Wired for War: The Robotics Revolution and Conflict in the Twenty-first Century |date=2009 |publisher=Penguin |isbn=978-1-4406-8597-2 |via=Google Books |access-date=10 September 2012 |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323123553/https://books.google.com/books?id=6aStP3Du5cgC&pg=PT50#v=onepage&q&f=false |url-status=live }}</ref> Tesla took the opportunity to further demonstrate "Teleautomatics" in an address to a meeting of the Commercial Club in Chicago, while he was traveling to [[Colorado Springs, Colorado|Colorado Springs]], on 13 May 1899.{{sfn|Seifer|2001|p=266}}

== Wireless power ==
{{Further|Wireless power transfer#Tesla}}

[[File:Teslathinker.jpg|thumb|upright|left|Tesla sitting in front of a spiral coil used in his wireless power experiments at his East Houston St. laboratory]]

From the 1890s through 1906, Tesla spent a great deal of his time and fortune on a series of projects trying to develop [[Wireless power transfer|the transmission of electrical power without wires]]. At the time, there was no feasible way to wirelessly transmit communication signals over long distances, let alone large amounts of power. Tesla had studied radio waves early on, and came to the conclusion that part of the existing study on them, by Hertz, was incorrect.{{sfn|Carlson|2013|p=127}}<ref name="earlyradiohistory.us">{{cite web| url=https://earlyradiohistory.us/tesla.htm| title=Nikola Tesla: The Guy Who Didn't 'Invent Radio'| first=Thomas H.| last=White| date=1 November 2012| website=earlyradiohistory.us| access-date=20 February 2018| archive-date=15 November 2019| archive-url=https://web.archive.org/web/20191115150200/http://earlyradiohistory.us/tesla.htm| url-status=live}}</ref>{{efn|Tesla's own experiments led him to erroneously believe Hertz had misidentified a form of conduction instead of a new form of electromagnetic radiation, an incorrect assumption that Tesla held for a couple of decades.<ref name="earlyradiohistory.us"/>{{sfn|Carlson|2013|pp=127–128}}}} Tesla noted that, even if theories on radio waves were true, they were worthless for his intended purposes, since this form of "invisible light" would diminish over a distance just like any other radiation and would travel in straight lines out into space, becoming "hopelessly lost".{{sfn|Carlson|2013|p=209}} He worked on the idea that he might be able to conduct electricity long distance through the Earth or the atmosphere, and began working on experiments to test this idea including setting up a large resonance transformer [[magnifying transmitter]] in his East Houston Street lab.<ref>"Tesla on Electricity Without Wires," <u>Electrical Engineer</u> – N.Y., 8 January 1896, p. 52. (Refers to letter by Tesla in the ''New York Herald'', 31 December 1895.)</ref><ref>''Mining & Scientific Press'', "Electrical Progress" Nikola Tesla Is Credited With Statement", 11 April 1896</ref> 

=== Colorado Springs ===
{{see|Tesla Experimental Station|Magnifying transmitter|Colorado Springs Notes, 1899–1900}}

[[File:Tesla Colorado.jpg|thumb|upright|Tesla's Colorado Springs laboratory]]

To further study the conductive nature of low-pressure air, Tesla set up an [[Tesla Experimental Station|experimental station]] at high altitude in Colorado Springs during 1899.{{sfn|Cheney|Uth|Glenn|1999|p=92}}<ref>{{cite web|url=https://www.pbs.org/tesla/ll/ll_colspr.html|title=PBS: Tesla – Master of Lightning: Colorado Springs|website=[[pbs.org]]|access-date=6 September 2017|archive-date=7 July 2017|archive-url=https://web.archive.org/web/20170707120257/http://www.pbs.org/tesla/ll/ll_colspr.html|url-status=live}}</ref>{{sfn|Carlson|2013|p=264}}<ref name="Wireless Telegraphy 2002, p. 109">''Nikola Tesla on his Work with Alternating Currents and their Application to Wireless Telegraphy, Telephony, and Transmission of Power'', Leland I. Anderson, 21st Century Books, 2002, p. 109, {{ISBN|1-893817-01-6}}.</ref> There he could safely operate much larger coils than in his New York lab, and the El Paso Electric Light Company supplied alternating current free of charge.<ref name="Wireless Telegraphy 2002, p. 109"/> To fund his experiments, he convinced [[John Jacob Astor IV]] to invest $100,000 (${{Inflation|US|100000|1899|r=-2|fmt=c}} in today's dollars{{Inflation-fn|US}}) to become a majority shareholder in the Nikola Tesla Company.{{sfn|Carlson|2013|pp=255–259}} Upon his arrival, he told reporters that he planned to conduct [[wireless telegraphy]] experiments, transmitting signals from [[Pikes Peak]] to Paris.{{sfn|Cheney|2001|p=173}}

[[File:Nikola Tesla, with his equipment Wellcome M0014782 - restoration2.jpg|thumb|left|A [[multiple exposure]] picture of Tesla sitting next to his "[[magnifying transmitter]]" generating millions of volts. The {{convert|7|m|adj=on}} long arcs were not part of the normal operation, but only produced for effect by rapidly cycling the power switch.{{sfn|Carlson|2013|pp=290–301}}]]

There, he experimented with a large coil operating in the megavolts range, producing artificial lightning (and thunder) consisting of millions of volts and discharges of up to {{convert|135|ft|m|0}} in length,<ref>Gillispie, Charles Coulston, "''Dictionary of Scientific Biography'';" ''Tesla, Nikola''. Charles Scribner's Sons, New York.</ref> and, at one point, inadvertently burned out the generator in El Paso, causing a power outage.<ref>{{cite journal |last=Secor |first=H. Winfield |title=Tesla's views on electricity and the war |journal=The Electrical Experimenter |date=August 1917 |url=http://www.tfcbooks.com/tesla/1917-08-00.htm |access-date=9 September 2012 |archive-date=10 February 2011 |archive-url=https://web.archive.org/web/20110210071635/http://tfcbooks.com/tesla/1917-08-00.htm |url-status=live }}</ref> The observations he made of the electronic noise of lightning strikes led him to (incorrectly) conclude that he could use the entire globe of the Earth to conduct electrical energy.{{sfn|Carlson|2013|p=301}}{{sfn|Cooper|2015|p=165}}

During his time at his laboratory, Tesla observed unusual signals from his receiver which he speculated to be communications from another planet. He mentioned them in a letter to a reporter in December 1899<ref>Daniel Blair Stewart (1999). ''Tesla: The Modern Sorcerer'', Frog Book. p. 372</ref> and to the [[Red Cross Society]] in December 1900.{{sfn|Carlson|2013|p=315}}{{sfn|Seifer|1998|pp=220–223}} Reporters treated it as a sensational story and jumped to the conclusion Tesla was hearing signals from [[Mars]].{{sfn|Carlson|2013|p=315}} He expanded on the signals he heard in a 9 February 1901 ''Collier's Weekly'' article entitled "Talking With Planets", where he said it had not been immediately apparent to him that he was hearing "intelligently controlled signals" and that the signals could have come from Mars, [[Venus]], or other planets.{{sfn|Seifer|1998|pp=220–223}}

Tesla had an agreement with the editor of ''[[The Century Magazine]]'' to produce an article on his findings. The magazine sent a photographer to Colorado to photograph the work being done there. The article, titled "The Problem of Increasing Human Energy", appeared in the June 1900 edition of the magazine. He explained the superiority of the wireless system he envisioned but the article was more of a lengthy philosophical treatise than an understandable scientific description of his work.<ref>{{Cite web|url=http://www.teslamemorialsociety.org/info/Research%20of%20Nikola%20Tesla%20in%20Long%20Island%20Laboratory.htm|title=Research of Nikola Tesla in Long Island Laboratory|access-date=26 January 2017|archive-date=6 May 2016|archive-url=https://web.archive.org/web/20160506115345/http://www.teslamemorialsociety.org/info/Research%20of%20Nikola%20Tesla%20in%20Long%20Island%20Laboratory.htm|url-status=live}}</ref>

=== Wardenclyffe ===
{{main|Wardenclyffe Tower}}

[[File:Tesla Broadcast Tower 1904.jpeg|thumb|upright|Tesla's Wardenclyffe plant on Long Island in 1904. From this facility, Tesla hoped to demonstrate wireless transmission of electrical energy across the Atlantic.]]

Tesla made the rounds in New York trying to find investors for what he thought would be a viable system of wireless transmission, wining and dining them at the [[Waldorf-Astoria (1893–1929)|Waldorf-Astoria]]'s Palm Garden (the hotel where he was living at the time), [[The Players (New York City)|The Players Club]], and [[Delmonico's]].<ref name="teslascience.org">{{cite web|url=http://www.teslascience.org/pages/dream.htm|title=Tesla Wardenclyffe Project Update – An Introduction to the Issues|website=www.teslascience.org|date=22 June 2023|access-date=26 January 2017|archive-date=21 January 2017|archive-url=https://web.archive.org/web/20170121115706/http://www.teslascience.org/pages/dream.htm|url-status=live}}</ref> In March 1901, he obtained $150,000 (${{Inflation|US|150000|1900|r=-2|fmt=c}} in today's dollars{{Inflation-fn|US}}) from [[J. P. Morgan]] in return for a 51% share of any generated wireless patents, and began planning the [[Wardenclyffe Tower]] facility to be built in [[Shoreham, New York]], {{convert|100|mi|km|0}} east of the city on the North Shore of Long Island.<ref name="broad1">{{cite news |last=Broad |first=William J |title=A Battle to Preserve a Visionary's Bold Failure |url=https://www.nytimes.com/2009/05/05/science/05tesla.html |access-date=20 May 2013 |newspaper=The New York Times |date=4 May 2009 |archive-date=25 July 2018 |archive-url=https://web.archive.org/web/20180725111710/https://www.nytimes.com/2009/05/05/science/05tesla.html |url-status=live }}</ref>

By July 1901, Tesla had expanded his plans to build a more powerful transmitter to leap ahead of [[Guglielmo Marconi|Marconi]]'s radio-based system, which Tesla thought was a copy of his own.{{sfn|Carlson|2013|p=315}} In December 1901, Marconi transmitted the letter S from England to [[Newfoundland and Labrador#colony|Newfoundland]], defeating Tesla in the race to be first to complete such a transmission.{{sfn|Carlson|2013|p=315}} In June 1902, Tesla moved his lab operations from Houston Street to Wardenclyffe.<ref name="broad1"/>

Investors on [[Wall Street]] put money into Marconi's system, and some in the press began turning against Tesla's project, claiming it was a hoax.<ref>Malanowski, Gregory, <u>The Race for Wireless</u>, AuthorHouse, p. 35</ref> The project came to a halt in 1905, perhaps contributing to what biographer [[Marc J. Seifer]] suspects was a nervous breakdown on Tesla's part in 1906.<ref>{{cite book |first=David Hatcher |last=Childress |date=1993 |isbn=978-0-932813-19-0 |title=The Fantastic Inventions of Nikola Tesla |page=255 |publisher=Adventures Unlimited}}</ref> Tesla mortgaged the Wardenclyffe property to cover his debts at the Waldorf-Astoria, which eventually amounted to $20,000 (${{Inflation|US|20000|1914|r=-2|fmt=c}} in today's dollars{{Inflation-fn|US}}).<ref>{{cite book |url=https://books.google.com/books?id=KRg9HWakBmQC&q=tesla+1908+Wardenclyffe+foreclosed&pg=PA185|title=Nikola Tesla on His Work with Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power: An Extended Interview |first=Nikola |last=Tesla |date=8 December 2017 |publisher=21st Century Books |isbn=978-1-893817-01-2 |access-date=18 November 2020 |archive-date=23 March 2024|archive-url=https://web.archive.org/web/20240323123554/https://books.google.com/books?id=KRg9HWakBmQC&q=tesla+1908+Wardenclyffe+foreclosed&pg=PA185#v=snippet&q=tesla%201908%20Wardenclyffe%20foreclosed&f=false |url-status=live}}</ref>

== Later years ==
After Wardenclyffe closed, Tesla continued to write to Morgan; after "the great man" died, Tesla wrote to Morgan's son Jack, trying to get further funding for the project. In 1906, Tesla opened offices at 165 Broadway in Manhattan, trying to raise further funds by developing and marketing his patents. He went on to have offices at the [[Metropolitan Life Insurance Company Tower|Metropolitan Life Tower]] from 1910 to 1914; rented for a few months at the [[Woolworth Building]], moving out because he could not afford the rent; and then to office space at 8 West 40th Street from 1915 to 1925. After moving to 8 West 40th Street, he was effectively bankrupt. Most of his patents had run out and he was having trouble with the new inventions he was trying to develop.{{sfn|Carlson|2013|pp=373–375}}

=== Bladeless turbine ===
{{main|Tesla turbine}}

[[File:TeslaTurbineOriginal.png|thumb|Tesla's bladeless turbine design]]

On his 50th birthday, in 1906, Tesla demonstrated a {{convert|200|hp|kW|abbr=off}} 16,000&nbsp;rpm [[Tesla turbine|bladeless turbine]]. During 1910–1911, at the [[Waterside Generating Station|Waterside Power Station]] in New York, several of his bladeless turbine engines were tested at 100–5,000&nbsp;hp.{{sfn|Carlson|2013|p=371}} Tesla worked with several companies including from 1919 to 1922 in [[Milwaukee]], for [[Allis-Chalmers]].{{sfn|Seifer|2001|p=398}}{{sfn|Carlson|2013|p=373}} Tesla licensed the idea to a precision instrument company, and it found use in the form of luxury car [[speedometer]]s and other instruments.{{sfn|Cheney|Uth|Glenn|1999|p=115}}

=== Wireless lawsuits ===
When [[World War I]] broke out, the British cut the transatlantic telegraph cable linking the US to [[German Empire|Germany]] in order to control the flow of information between the two countries. They also tried to shut off German wireless communication to and from the US by having the US Marconi Company sue the German radio company [[Telefunken]] for patent infringement.{{sfn|Carlson|2013|p=377}} Telefunken brought in the physicists [[Jonathan Zenneck]] and [[Karl Ferdinand Braun]] for their defense, and hired Tesla as a witness for two years for $1,000 a month. The case stalled and then went moot when the US entered the war against Germany in 1917.{{sfn|Carlson|2013|p=377}}{{sfn|Seifer|2001|p=373}}

In 1915, Tesla attempted to sue the [[Marconi Company]] for infringement of his wireless tuning patents. Marconi's initial radio patent had been awarded in the US in 1897, but his 1900 patent submission covering improvements to radio transmission had been rejected several times on the grounds that it infringed on other existing patents, including two 1897 Tesla wireless power tuning patents, before it was finally approved in 1904.<ref name="earlyradiohistory.us" /><ref>Howard B. Rockman, Intellectual Property Law for Engineers and Scientists, John Wiley & Sons – 2004, p. 198.</ref><ref>{{Cite web|url=https://supreme.justia.com/cases/federal/us/320/1/|title=Marconi Wireless Tel. Co. v. United States, 320 U.S. 1 (1943)|website=Justia Law|access-date=29 January 2017|archive-date=25 June 2017|archive-url=https://web.archive.org/web/20170625130248/https://supreme.justia.com/cases/federal/us/320/1/|url-status=live}}</ref> Tesla's 1915 case went nowhere,{{sfn|Carlson|2013|p=377-378}} but in a related case, where the Marconi Company tried to sue the US government over WWI patent infringements, a [[Supreme Court of the United States]] 1943 decision restored the prior patents of [[Oliver Lodge]], [[John Stone Stone|John Stone]], and Tesla.<ref name="LQsxMxEUC page 3">{{cite book |url=https://books.google.com/books?id=c92LQsxMxEUC&q=British+Court+tesla+radio&pg=PA3 |title=Jean-Michel Redouté, Michiel Steyaert, EMC of Analog Integrated Circuits |page=3 |access-date=18 March 2013 |isbn=978-90-481-3230-0 |last1=Redouté |first1=Jean-Michel |last2=Steyaert |first2=Michiel |date=10 October 2009 |publisher=Springer |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323123811/https://books.google.com/books?id=c92LQsxMxEUC&q=British+Court+tesla+radio&pg=PA3#v=snippet&q=British%20Court%20tesla%20radio&f=false |url-status=live }}</ref> The court declared that their decision had no bearing on Marconi's claim as the first to achieve radio transmission, just that since Marconi's claim to certain patented improvements were questionable, the company could not claim infringement on those same patents.<ref name="earlyradiohistory.us" /><ref>{{cite book |url=https://books.google.com/books?id=SdGaiV6iup0C&q=supreme+court+1943+radio+marconi&pg=PA3 |title=Robert Sobot, Wireless Communication Electronics:Introduction to RF Circuits and Design Techniques |page=4 |date=18 February 2012 |access-date=18 March 2013 |isbn=978-1-4614-1116-1 |last1=Sobot |first1=Robert |publisher=Springer |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323123556/https://books.google.com/books?id=SdGaiV6iup0C&q=supreme+court+1943+radio+marconi&pg=PA3#v=snippet&q=supreme%20court%201943%20radio%20marconi&f=false |url-status=live }}</ref>

=== Other ideas ===
[[File:Second banquet meeting of the Institute of Radio Engineers.jpg |thumb |Second banquet meeting of the Institute of Radio Engineers, 23 April 1915. Tesla is seen standing in the center.]]

Tesla attempted to market several devices based on the production of ozone. These included his 1900 Tesla Ozone Company selling an 1896 patented device based on his Tesla coil, used to bubble ozone through different types of oils to make a therapeutic gel.<ref>Anand Kumar Sethi (2016). ''The European Edisons: Volta, Tesla, and Tigerstedt'', Springer. pp. 53–54</ref> He tried to develop a variation of this a few years later as a room sanitizer for hospitals.{{sfn |Carlson |2013 |p=353}} 

He theorized that the application of electricity to the brain enhanced intelligence. In 1912, he crafted "a plan to make dull students bright by saturating them unconsciously with electricity," wiring the walls of a schoolroom and, "saturating [the schoolroom] with infinitesimal electric waves vibrating at high frequency. The whole room will thus, Mr. Tesla claims, be converted into a health-giving and stimulating electromagnetic field or 'bath.{{'-}}"<ref name="Gilliams">{{cite web |last1=Gilliams |first1=E. Leslie |title=Tesla's Plan of Electrically Treating Schoolchildren |url=http://www.teslacollection.com/tesla_articles/1912/popular_electricity_magazine/e_leslie_gilliams/tesla_s_plan_of_electrically_treating_school_children |via=teslacollection.com |work=Popular Electricity Magazine |date=1912 |access-date=19 August 2014 |archive-date=9 January 2015 |archive-url=https://web.archive.org/web/20150109004431/http://www.teslacollection.com/tesla_articles/1912/popular_electricity_magazine/e_leslie_gilliams/tesla_s_plan_of_electrically_treating_school_children |url-status=live }}</ref> The plan was, at least provisionally, approved by then superintendent of New York City schools, William H. Maxwell.<ref name="Gilliams"/>

In the August 1917 edition of the magazine ''[[Electrical Experimenter]]'', Tesla postulated that electricity could be used to locate submarines via using the reflection of an "electric ray" of "tremendous frequency," with the signal being viewed on a fluorescent screen (a system that has been noted to have a superficial resemblance to modern [[radar]]).<ref>[[Margaret Cheney (author)|Margaret Cheney]], Robert Uth, Jim Glenn, ''Tesla, Master of Lightning,'' pp. 128–129</ref> Tesla was incorrect in his assumption that high-frequency radio waves would penetrate water.<ref>{{cite book |url=https://books.google.com/books?id=W1JAeg1PiWIC&pg=PA154 |title=Lewis Coe (2006). ''Wireless Radio: A History''. McFarland. p. 154 |isbn=978-0-7864-2662-1 |last1=Coe |first1=Lewis |date=8 February 2006 |publisher=McFarland }}</ref> [[Émile Girardeau]], who helped develop France's first radar system in the 1930s, noted in 1953 that Tesla's general speculation that a very strong high-frequency signal would be needed was correct.<!-- This sentence seems to contradict the previous one. --> Girardeau said, "(Tesla) was prophesying or dreaming, since he had at his disposal no means of carrying them out, but one must add that if he was dreaming, at least he was dreaming correctly".{{sfn |Cheney |2001 |p=266}}

In 1928, Tesla received patent, {{US patent|1,655,114}}, for a [[biplane]] design capable of [[vertical take-off and landing]] (VTOL), which "gradually tilted through manipulation of the elevator devices" in flight until it was flying like a conventional plane.<ref>{{cite web |last=Tesla |first=Nikola |title=Tesla Patent 1,655,114 Apparatus for Aerial Transportation. |url=https://teslauniverse.com/nikola-tesla-patents-1,655,114-aerial-transportation |publisher=U.S. Patent Office |access-date=20 July 2012 |archive-date=20 July 2012 |archive-url=https://web.archive.org/web/20120720092018/http://www.teslauniverse.com/nikola-tesla-patents-1,655,114-aerial-transportation |url-status=live }}</ref> This impractical design was something Tesla thought would sell for less than $1,000.{{sfn |Cheney |2001 |p=251}}<ref name="airspacemag">{{cite web |url=https://www.smithsonianmag.com/air-space-magazine/nikola-teslas-curious-contrivance-10187565/ |title='Nikola Tesla's Curious Contrivance' by A.J.S. RAYL Air & Space magazine, September 2006, reprint at History of Flight |publisher=airspacemag.com |access-date=10 September 2012 |archive-date=27 January 2022 |archive-url=https://web.archive.org/web/20220127184244/https://www.smithsonianmag.com/air-space-magazine/nikola-teslas-curious-contrivance-10187565/ |url-status=live }}</ref>

=== Living circumstances ===
Tesla lived at the Waldorf Astoria Hotel in New York City from 1900 and ran up a large bill.{{sfn|Cheney|Uth|Glenn|1999|p=125}} He moved to the [[St. Regis New York|St. Regis Hotel]] in 1922 and followed a pattern from then on of moving to a different hotel every few years and leaving unpaid bills behind.{{sfn|Carlson|2013|p=467-468}}{{sfn|O'Neill|1944|p=359}}

Tesla walked to the park every day to feed the pigeons. He began feeding them at the window of his hotel room and nursed injured birds back to health.{{sfn|O'Neill|1944|p=359}}<ref>{{cite web|title=About Nikola Tesla |url=http://www.teslasociety.org/about.html |publisher=Tesla Memorial Society of NY |access-date=5 July 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120525133151/http://www.teslasociety.org/about.html |archive-date=25 May 2012 }}</ref><ref>{{cite web |title=Tesla Life and Legacy&nbsp;– Poet and Visionary |url=https://www.pbs.org/tesla/ll/ll_poevis.html |publisher=PBS |access-date=5 July 2012 |archive-date=8 July 2012 |archive-url=https://web.archive.org/web/20120708101441/http://www.pbs.org/tesla/ll/ll_poevis.html |url-status=live }}</ref> He said that he had been visited by a certain injured white pigeon daily. He spent over $2,000 ({{Inflation|US|2000|1922|r=-1|fmt=eq}}) to care for the bird, including a device he built to support her comfortably while her broken wing and leg healed.{{sfn|Seifer|2001|p=414}}<ref>{{cite web|title=About Nikola Tesla |url=http://www.teslasociety.org/about.html |publisher=Tesla Society of USA and Canada |access-date=5 July 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120525133151/http://www.teslasociety.org/about.html |archive-date=25 May 2012 }}</ref> Tesla's unpaid bills, as well as complaints about the mess made by pigeons, led to his eviction from St. Regis in 1923. He was forced to leave the [[Hotel Pennsylvania]] in 1930 and the Hotel Governor Clinton in 1934.{{sfn|O'Neill|1944|p=359}} At one point he took rooms at the [[Hotel Marguery]].{{sfn|Cheney|Uth|Glenn|1999|p=135}} 
Tesla moved to the [[Wyndham New Yorker Hotel|Hotel New Yorker]] in 1934. At this time Westinghouse Electric & Manufacturing Company began paying him $125 ({{Inflation|US|125|1934|r=-1|fmt=eq}}) per month in addition to paying his rent. Accounts of how this came about vary. Several sources claim that Westinghouse was concerned, or possibly warned, about potential bad publicity arising from the impoverished conditions in which their former star inventor was living.{{sfn|Jonnes|2004|p=365}}<ref>{{harvnb|Cheney|Uth|Glenn|1999|p=149}}</ref><ref name="Seifer435">{{harvnb|Seifer|2001|p=435}}</ref>{{sfn|Carlson|2013|p=379}} The payment has been described as being couched as a "consulting fee" to get around Tesla's aversion to accepting charity. Tesla biographer Marc Seifer described the Westinghouse payments as a type of "unspecified settlement".<ref name="Seifer435" />

=== Birthday press conferences ===
[[File:Nikola Tesla on Time Magazine 1931.jpg|thumb|upright|Tesla on [[Time (magazine)|''Time'' magazine]] commemorating his 75th birthday]]

In 1931, a young journalist whom Tesla befriended, [[Kenneth M. Swezey]], organized a celebration for the inventor's 75th birthday.<ref>{{Cite web|url=http://www.davidjkent-writer.com/2012/07/10/happy-birthday-nikola-tesla-a-scientific-rock-star-is-born/|title=Happy Birthday, Nikola Tesla – A Scientific Rock Star is Born|last=Kent|first=David J.|date=10 July 2012|website=Science Traveler|language=en-US|access-date=26 January 2019|archive-date=26 January 2019|archive-url=https://web.archive.org/web/20190126221049/http://www.davidjkent-writer.com/2012/07/10/happy-birthday-nikola-tesla-a-scientific-rock-star-is-born/|url-status=live}}</ref> Tesla received congratulations from figures in science and engineering such as [[Albert Einstein]],<ref>{{cite web|url=http://www.teslasociety.com/time.jpg|title=Time front cover, Vol XVIII, No. 3|date=20 July 1931|access-date=10 September 2012|archive-date=7 July 2018|archive-url=https://web.archive.org/web/20180707163714/http://www.teslasociety.com/time.jpg|url-status=live}}</ref> and he was also featured on the cover of [[Time magazine|''Time'' magazine]].<ref>{{cite magazine |title=Nikola Tesla|url=http://www.time.com/time/covers/0,16641,19310720,00.html|archive-url=https://web.archive.org/web/20070708020011/http://www.time.com/time/covers/0,16641,19310720,00.html|url-status=dead|archive-date=8 July 2007|magazine=Time|access-date=2 July 2012}}</ref> The cover caption "All the world's his power house" noted his contribution to [[Electricity generation|electrical power generation]]. The party went so well that Tesla made it an annual event, an occasion where he would put out a large spread of food and drink—featuring dishes of his own creation. He invited the press in order to see his inventions and hear stories about his past exploits, views on current events, and sometimes baffling claims.{{sfn|Cheney|2001|p=151}}{{sfn|Carlson|2013|pp=380–382}}

[[File:Teslathoughtcamera.jpeg|thumb|Newspaper representation of the thought camera Tesla described at his 1933 birthday party]]

At the 1932 party, Tesla claimed he had invented a motor that would run on [[cosmic ray]]s.{{sfn|Carlson|2013|pp=380–382}}
In 1933, at age 77, Tesla told reporters at the event that, after 35 years of work, he was on the verge of producing proof of a new form of energy. He claimed it was a theory of energy that was "violently opposed" to Einsteinian physics and could be tapped with an apparatus that would be cheap to run and last 500 years. He also told reporters he was working on a way to transmit individualized private radio wavelengths, working on breakthroughs in [[metallurgy]], and developing a way to photograph the [[retina]] to record thought.<ref>Tesla Predicts New Source of Power in Year, New York Herald Tribune, 9 July 1933</ref>

At the 1934 occasion, Tesla told reporters he had designed a [[superweapon]] he claimed would end all war.<ref>{{cite magazine |title=Tesla's Ray |magazine=Time |date=23 July 1934}}</ref><ref name="seifer1">{{cite web |last=Seifer |first=Marc |title=Tesla's "Death Ray" Machine |url=http://www.bibliotecapleyades.net/tesla/esp_tesla_2.htm |publisher=bibliotecapleyades.net |access-date=4 July 2012 |archive-date=24 June 2006 |archive-url=https://web.archive.org/web/20060624171605/http://www.bibliotecapleyades.net/tesla/esp_tesla_2.htm |url-status=live }}</ref> He called it "[[teleforce]]", but was usually referred to as his [[death ray]].<ref>[[Margaret Cheney (author)|Cheney, Margaret]] & Uth, Robert (2001). Tesla: Master of Lightning. Barnes & Noble Books. p. 158</ref> In 1940, the ''[[New York Times]]'' gave a range for the ray of {{convert|250|mi}}, with an expected development cost of US$2&nbsp;million (equivalent to ${{Inflation|US|2|1940|r=2}}&nbsp;million in {{Inflation/year|US}}).<ref name="pmnyt1940">{{cite web |url=https://www.popularmechanics.com/science/energy/a44197280/did-the-us-government-steal-nikola-teslas-research/ |title=Did the U.S. Government Really Steal Nikola Tesla's Research Papers? |first=Jessica |last=Coulon |date=14 June 2023 |access-date=26 June 2023 |work=[[Popular Mechanics]] |archive-date=26 June 2023 |archive-url=https://web.archive.org/web/20230626231358/https://www.popularmechanics.com/science/energy/a44197280/did-the-us-government-steal-nikola-teslas-research/ |url-status=live }}</ref> Tesla described it as a defensive weapon that would be put up along the border of a country and be used against attacking ground-based infantry or aircraft. Tesla never revealed detailed plans of how the weapon worked during his lifetime but, in 1984, they surfaced at the [[Nikola Tesla Museum]] archive in [[Belgrade]].{{sfn|Carlson|2013|p=382}} The treatise, ''The New Art of Projecting Concentrated Non-dispersive Energy through the Natural Media'', described an open-ended vacuum tube with a gas jet seal that allows particles to exit, a method of charging slugs of tungsten or mercury to millions of volts, and directing them in streams (through [[electrostatic]] repulsion).{{sfn|Carlson|2013|pp=380–382}}{{sfn|Seifer|1998|p=454}} Tesla tried to attract interest of the [[United States Department of Defense|US War Department]],<ref>"Aerial Defense 'Death-Beam' Offered to U.S. By Tesla" 12 July 1940</ref> United Kingdom, Soviet Union, and Yugoslavia in the device.<ref>{{cite web |last=Seifer |first=Marc J. |title=Tesla's "death ray" machine |url=http://www.bibliotecapleyades.net/tesla/esp_tesla_2.htm |access-date=5 September 2012 |archive-date=24 June 2006 |archive-url=https://web.archive.org/web/20060624171605/http://www.bibliotecapleyades.net/tesla/esp_tesla_2.htm |url-status=live }}</ref>

In 1935, at his 79th birthday party, Tesla covered many topics. He claimed to have discovered the cosmic ray in 1896 and invented a way to produce direct current by [[Inductive charging|induction]], and made many claims about his mechanical oscillator.<ref name="ReferenceA">Earl Sparling, Nikola Tesla, at 79, Uses Earth to Transmit Signals: Expects to Have $100,000,000 within Two Years, New York World-Telegram, 11 July 1935</ref> Describing the device (which he expected would earn him $100 million within two years) he told reporters that a version of his oscillator had caused an earthquake in his 46 East Houston Street lab and neighboring streets in [[Lower Manhattan]] in 1898.<ref name="ReferenceA" /> He went on to tell reporters his oscillator could destroy the [[Empire State Building]] with {{convert|5|lb}} of air pressure.{{sfn|Carlson|2013|p=380}} He also proposed using his oscillators to transmit vibrations into the ground. He claimed it would work over any distance and could be used for communication or locating underground mineral deposits, a technique he called "telegeodynamics".<ref name=Anderson>{{cite book |last=Anderson |first=Leland |title=Nikola Tesla's teleforce & telegeodynamics proposals |year=1998 |publisher=21st Century Books |location=Breckenridge, Colo. |isbn=0-9636012-8-8}}</ref>

In 1937, at his event in the Grand Ballroom of the Hotel New Yorker, Tesla received the [[Order of the White Lion]] from the Czechoslovak ambassador and a medal from the Yugoslav ambassador. On questions concerning the death ray, Tesla stated: "But it is not an experiment&nbsp;... I have built, demonstrated and used it. Only a little time will pass before I can give it to the world."{{sfn|Carlson|2013|pp=380–382}}

== Awards ==
Tesla won numerous medals and awards. They include:

<!--* Grand Officer of the [[Order of St. Sava]] ([[Kingdom of Serbia |Serbia]], 1892)-->
* [[Elliott Cresson Medal]] ([[Franklin Institute]], US, 1894)<ref name="pg">{{cite book |last1=Goldman |first1=Phyllis |title=Monkeyshines on Great Inventors |date=1997 |publisher=EBSCO Publishing, Inc. |location=Greensboro, NC |isbn=978-1-888325-04-1 |page=15 |url=https://books.google.com/books?id=SKOmiByD_X8C |access-date=14 May 2020 |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323123811/https://books.google.com/books?id=SKOmiByD_X8C |url-status=live}}</ref>
* Grand Cross of the [[Order of Prince Danilo I]] ([[Principality of Montenegro |Montenegro]], 1895)<ref>{{Cite book |last=Acović |first=Dragomir |title=Slava i čast: Odlikovanja među Srbima, Srbi među odlikovanjima |year=2012 |location=Belgrade |publisher=Službeni Glasnik |pages=85}}</ref>
* Member of the [[American Philosophical Society]] (US, 1896)<ref>{{Cite web |title=APS Member History |url=https://search.amphilsoc.org/memhist/search?creator=Nikola+Tesla&title=&subject=&subdiv=&mem=&year=&year-max=&dead=&keyword=&smode=advanced |access-date=11 March 2024 |website=American Philosophical Society |archive-date=11 March 2024 |archive-url=https://web.archive.org/web/20240311152707/https://search.amphilsoc.org/memhist/search?creator=Nikola+Tesla&title=&subject=&subdiv=&mem=&year=&year-max=&dead=&keyword=&smode=advanced |url-status=live }}</ref>
* [[AIEE Edison Medal]] ([[Institute of Electrical and Electronics Engineers]], US, 1916)<ref name="EdisonMedal">{{cite web |title=IEEE Edison Medal Recipient List |url=https://www.ieee.org/content/dam/ieee-org/ieee/web/org/about/awards/recipients/edison_rl.pdf |publisher=Institute of Electrical and Electronics Engineers (IEEE) |access-date=4 June 2022 |archive-date=28 January 2021 |archive-url=https://web.archive.org/web/20210128155822/https://www.ieee.org/content/dam/ieee-org/ieee/web/org/about/awards/recipients/edison_rl.pdf |url-status=dead}}</ref>
* Grand Cross of the [[Order of St. Sava]] ([[Kingdom of Serbs, Croats and Slovenes |Yugoslavia]], 1926)<ref name="eserbia">{{cite web |title=Culture |url=http://www.eserbia.org/culture/lectures/288-nikola-tesla-and-the-serbian-orthodox-church-a-st-sava-s-day-reflection |website=www.eserbia.org |access-date=16 January 2017 |archive-date=13 February 2017 |archive-url=https://web.archive.org/web/20170213134050/http://www.eserbia.org/culture/lectures/288-nikola-tesla-and-the-serbian-orthodox-church-a-st-sava-s-day-reflection |url-status=live}}</ref>
<!--* Cross of the [[Order of the Yugoslav Crown]] ([[Kingdom of Yugoslavia |Yugoslavia]], 1931)-->
* [[John Scott Medal]] ([[Franklin Institute]] & [[Philadelphia City Council]], US, 1934)<ref name=pg />
* [[Order of the White Eagle (Serbia) |Order of the White Eagle]] ([[Kingdom of Yugoslavia |Yugoslavia]], 1936)<ref>{{Cite web |last=Stanković |first=Dario |date=9 July 2011 |title=Prošlo 155 godina od rođenja Nikole Tesle a njegova djela postaju sve veća |url=https://www.nezavisne.com/nauka-tehnologija/nauka/Proslo-155-godina-od-rodjenja-Nikole-Tesle-a-njegova-djela-postaju-sve-veca/96911 |access-date=15 July 2025 |website=Nezavisne novine |language=sr}}</ref>
* Grand Cross of the [[Order of the White Lion]] ([[Czechoslovakia]], 1937){{sfn |Cheney |2011 |p=312}}
<!--* Medal of the [[University of Paris]] (Paris, France, 1937)-->
<!--* The Medal of the University St. Clement of Ochrida ([[Sofia, Bulgaria]], 1939)-->

== Death ==
[[File:Room3327HotelNewYorker.jpg|thumb|alt=Room 3327 of the Hotel New Yorker, where Tesla died|Room 3327 of the [[Wyndham New Yorker Hotel|Hotel New Yorker]], where Tesla died]]

In the fall of 1937 at the age of 81, after midnight one night, Tesla left the Hotel New Yorker to make his regular commute to [[St. Patrick's Cathedral (New York City)|St. Patrick's Cathedral]] and the [[New York Public Library Main Branch|Public Library]] to feed the pigeons. While crossing a street a couple of blocks from the hotel, Tesla was struck by a moving taxicab and was thrown to the ground. His back was severely wrenched and three of his ribs were broken in the accident. The full extent of his injuries was never known; Tesla refused to consult a doctor, an almost lifelong custom, and never fully recovered.{{sfn|O'Neill|1944|p=313}}{{sfn|Carlson|2013|p=389}} On the night of 7 January 1943, at the age of 86, Tesla died alone in his hotel room.<ref>{{cite web |last1=Fraga |first1=Kaleena |title=How Did Nikola Tesla Die? The Story Of The Famed Inventor's Tragic Demise |url=https://allthatsinteresting.com/nikola-tesla-death |website=All That's Interesting |date=October 2023 |access-date=15 July 2025}}</ref> His body was found by a maid on the next day when she entered his room, ignoring the "do not disturb" sign that had been placed on his door three days earlier. An assistant medical examiner examined the body, estimated the time of death as 10:30{{nbsp}}p.m. and ruled that the cause of death had been [[coronary thrombosis]].{{sfn|Cheney|2011|p=324}}

Two days later the [[Federal Bureau of Investigation]] ordered the [[Alien Property Custodian]] to seize Tesla's belongings. [[John G. Trump]], a professor at [[MIT|M.I.T.]] and a well-known electrical engineer serving as a technical aide to the [[National Defense Research Committee]], was called in to analyze the Tesla items. After a three-day investigation, Trump's report concluded that there was nothing which would constitute a hazard in unfriendly hands.<ref name="PBS 2001 missing papers">{{cite web |title=The Missing Papers |url=https://www.pbs.org/tesla/ll/ll_mispapers.html |publisher=PBS |date=24 January 2001 |access-date=5 July 2012 |archive-date=24 January 2001 |archive-url=https://web.archive.org/web/20010124064300/https://www.pbs.org/tesla/ll/ll_mispapers.html |url-status=live }}</ref> In a box purported to contain a part of Tesla's "death ray", Trump found a 45-year-old [[Decade Box|multidecade resistance box]].<ref>{{harvnb|Childress|1993|p=249}}</ref> On 10 January 1943, New York City mayor [[Fiorello La Guardia]] read a eulogy for Tesla at his funeral at the [[Cathedral of St. John the Divine]].<ref>{{cite web |title=Mayor Fiorello LaGuardia's Eulogy to Nikola Tesla on January 10, 1943 |url=https://www.teslasociety.com/eulogy.htm |publisher=Tesla Memorial Society of New York |access-date=15 July 2025}}</ref>

== Personal life and character ==
[[File:N.Tesla.JPG|thumb|upright|Tesla {{circa |1896}}]]

Tesla was a lifelong bachelor, who had once explained that his chastity was very helpful to his scientific abilities.{{sfn|Cheney|2001|p=33}} In an interview with the ''Galveston Daily News'' on 10 August 1924 he stated, "Now the soft-voiced gentlewoman of my reverent worship has all but vanished. In her place has come the woman who thinks that her chief success in life lies in making herself as much as possible like man—in dress, voice and actions..."{{sfn |Cheney |Uth |Glenn |1999 |p=135}} He told a reporter in later years that he sometimes felt that by not marrying, he had made too great a sacrifice to his work.{{sfn|Seifer|2001|p=414}}

Tesla was a good friend of [[Francis Marion Crawford]], Robert Underwood Johnson,<ref name="teslasociety1" /> [[Stanford White]],<ref>{{cite web |title=Stanford White |url=http://www.teslasociety.com/stanford.htm |publisher=Tesla Memorial Society of NY |access-date=4 July 2012 |archive-date=28 November 2010 |archive-url=https://web.archive.org/web/20101128204919/http://teslasociety.com/stanford.htm |url-status=live}}</ref> Fritz Lowenstein, George Scherff, and Kenneth Swezey.<ref>{{citation |first=Kenneth M. |last=Swezey |title=Papers 1891–1982 |volume=47 |url=http://americanhistory.si.edu/archives/d8047.htm |publisher=National Museum of American History |access-date=4 July 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120505004025/http://americanhistory.si.edu/archives/d8047.htm |archive-date=5 May 2012}}</ref><ref>{{cite web |title=Tribute to Nikola Tesla |url=http://www.teslasociety.com/posterbook.htm |publisher=Tesla Memorial Society of NY |access-date=4 July 2012 |archive-date=13 June 2011 |archive-url=https://web.archive.org/web/20110613113120/http://teslasociety.com/posterbook.htm |url-status=live}}</ref><ref>{{cite web |title=Nikola Tesla at Wardenclyffe |url=http://www.teslasociety.com/warden.htm |publisher=Tesla Memorial Society of NY |access-date=4 July 2012 |archive-date=29 November 2010 |archive-url=https://web.archive.org/web/20101129042338/http://teslasociety.com/warden.htm |url-status=live}}</ref> In middle age, Tesla became a close friend of Mark Twain; they spent a lot of time together in his lab and elsewhere.<ref name="teslasociety1">{{cite web |title=Famous Friends |url=http://www.teslasociety.com/famousfriends.htm |publisher=Tesla Memorial Society of NY |access-date=4 July 2012 |archive-date=28 November 2010 |archive-url=https://web.archive.org/web/20101128190309/http://teslasociety.com/famousfriends.htm |url-status=live}}</ref> Twain notably described Tesla's induction motor invention as "the most valuable patent since the telephone".<ref>{{cite news |title=Nikola Tesla: The patron saint of geeks? |url=https://www.bbc.co.uk/news/magazine-19503846 |work=News Magazine |publisher=BBC |access-date=10 September 2012 |date=10 September 2012 |archive-date=10 September 2012 |archive-url=https://web.archive.org/web/20120910191948/http://www.bbc.co.uk/news/magazine-19503846 |url-status=live}}</ref> At a party thrown by actress [[Sarah Bernhardt]] in 1896, Tesla met Indian Hindu monk [[Swami Vivekananda]]. Vivekananda later wrote that Tesla said he could demonstrate mathematically the relationship between matter and energy, something Vivekananda hoped would give a scientific foundation to [[Vedantic]] cosmology.<ref>Kak, S. (2017) Tesla, wireless energy transmission and Vivekananda. Current Science, vol. 113, 2207–2210.</ref><ref>{{cite book |url=https://books.google.com/books?id=30PeCQAAQBAJ&q=tesla+Vivekananda&pg=PT24 |title=Swami Vivekananda: A Contemporary Reader edited by Makarand R. Paranjape |isbn=978-1-317-44636-1 |last1=Paranjape |first1=Makarand R. |date=12 June 2015 |publisher=Routledge |access-date=4 May 2021 |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323124315/https://books.google.com/books?id=30PeCQAAQBAJ&q=tesla+Vivekananda&pg=PT24#v=snippet&q=tesla%20Vivekananda&f=false |url-status=live}}</ref> The meeting with Swami Vivekananda stimulated Tesla's interest in Eastern Science, which led to Tesla studying Hindu and [[Vedic philosophy]] for a number of years.<ref>{{Cite web |title=Nikola Tesla and Swami Vivekananda |url=https://www.teslasociety.com/tesla_and_swami.htm |access-date=20 December 2022 |website=www.teslasociety.com |archive-date=20 December 2022 |archive-url=https://web.archive.org/web/20221220143353/https://www.teslasociety.com/tesla_and_swami.htm |url-status=live }}</ref> Tesla later wrote an article titled "Man's Greatest Achievement" using Sanskrit terms [[akasha]] and [[prana]] to describe the relationship between matter and energy.<ref>{{Cite web |first=Arjun |last=Walia |title=The Influence Vedic Philosophy Had on Nikola Tesla's Idea of Free Energy |url=https://www.scienceandnonduality.com/article/the-influence-vedic-philosophy-had-on-nikola-teslas-idea-of-free-energy |access-date=20 December 2022 |website=SAND |language=en |archive-date=20 December 2022 |archive-url=https://web.archive.org/web/20221220143355/https://www.scienceandnonduality.com/article/the-influence-vedic-philosophy-had-on-nikola-teslas-idea-of-free-energy |url-status=live }}</ref><ref>{{Cite web |title=(PDF) Tesla (1930)-Man's Greatest Achievement.pdf |url=https://dokumen.tips/documents/tesla-1930-mans-greatest-achievementpdf.html |access-date=20 December 2022 |website=dokumen.tips |language=en |archive-date=20 December 2022 |archive-url=https://web.archive.org/web/20221220143359/https://dokumen.tips/documents/tesla-1930-mans-greatest-achievementpdf.html |url-status=live }}</ref> In the late 1920s, Tesla befriended [[George Sylvester Viereck]], a poet, writer, mystic, and later a [[Nazi]] propagandist. Tesla occasionally attended dinner parties held by Viereck and his wife.<ref>{{cite book |last1=Cheney |first1=Margaret |last2=Uth |first2=Robert |name-list-style=amp |date=2001 |title=Tesla: Master of Lightning |publisher=Barnes & Noble Books |page=137}}</ref><ref>{{cite book |last=Johnson |first=Neil M. |title=George Sylvester Viereck: Poet and Propagandist |publisher=Neil M. Johnson}}</ref>

Tesla could be harsh at times and openly expressed disgust for overweight people, such as when he fired a secretary because of her weight.{{sfn |Cheney |2001 |p=110}} He was quick to criticize clothing; on several occasions, Tesla directed a subordinate to go home and change her dress.{{sfn |Cheney |2001 |p=33}} When Thomas Edison died in 1931, Tesla contributed the only negative opinion to ''[[The New York Times]]''.<ref name="lifeEdison">{{cite book |title=Thomas Edison: Life of an Electrifying Man |last=Biographiq |year=2008 |isbn=978-1-59986-216-3 |page=23 |publisher=Filiquarian Publishing, LLC.}}</ref><ref name="Edisonobit">{{cite news |author=<!--not stated--> |title=Tesla says Edison was an empiricist |date=19 October 1931 |work=New York Times |page=27 |url=https://timesmachine.nytimes.com/timesmachine/1931/10/19/issue.html |access-date=15 January 2024 |ref=none |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323124240/https://timesmachine.nytimes.com/timesmachine/1931/10/19/issue.html |url-status=live }}</ref> He became a vegetarian in his later years, living on only milk, bread, honey, and vegetable juices.<ref name="seifer1" /><ref>{{cite web |last=Gitelman |first=Lisa |title=Reconciling the Visionary with the Inventor Wizard: The Life and Times of Nikola Tesla |url=https://www.technologyreview.com/1997/11/01/237150/reconciling-the-visionary-with-the-inventor/ |publisher=technology review (MIT) |access-date=3 June 2012 |date=1 November 1997 |archive-date=22 September 2020 |archive-url=https://web.archive.org/web/20200922054715/https://www.technologyreview.com/1997/11/01/237150/reconciling-the-visionary-with-the-inventor/ |url-status=live }}</ref>

== Views and beliefs ==
[[File:Nikola Tesla by Sarony c1885-crop.png|thumb|upright|Tesla {{circa}} 1885]]

=== On experimental and theoretical physics ===
Tesla disagreed with the theory that atoms were composed of smaller [[subatomic particle]]s, stating there was no such thing as an [[electron]] creating an electric charge. He believed that if electrons existed at all, they were some fourth state of matter or "sub-atom" that could exist only in an experimental vacuum, and that they had nothing to do with electricity.{{sfn|O'Neill|1944|p=249}}<ref>{{cite book |url=https://books.google.com/books?id=tCcDAAAAMBAJ&pg=PA171 |title="The Prophet of Science Looks Into The Future," Popular Science November 1928, p. 171 |access-date=18 March 2013 |date=November 1928 |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323124316/https://books.google.com/books?id=tCcDAAAAMBAJ&pg=PA171#v=onepage&q&f=false |url-status=live }}</ref> Tesla believed that atoms are immutable—they could not change state or be split in any way. He was a believer in the 19th-century concept of an all-pervasive [[Ether (classical element)|ether]] that transmitted electrical energy.<ref>{{harvnb|Seifer|2001|p=1745}}</ref>

Tesla opposed the equivalence of matter and energy.{{sfn|O'Neill|1944|p=247}} He was critical of Einstein's [[theory of relativity]], saying "I hold that space cannot be curved, for the simple reason that it can have no properties. It might as well be said that God has properties."<ref>''[[New York Herald Tribune]]'', 11 September 1932</ref> In 1935 he described relativity as "a beggar wrapped in purple whom ignorant people take for a king" and said his own experiments had measured the speed of cosmic rays from [[Antares]] as fifty times the speed of light.<ref name="NYT7-11-35">{{cite news |title=Tesla, 79, promises to transmit force |newspaper=New York Times |location=New York, NY |pages=23 |date=11 July 1935 |url=https://www.nytimes.com/1935/07/11/archives/tesla-79-promises-to-transmit-force-scientist-on-birthday-reveals.html |access-date=23 May 2025 |archive-url=https://web.archive.org/web/20220701054231/https://teslaresearch.jimdofree.com/articles-interviews/tesla-79-promises-to-transmit-force-new-york-times-july-11-1935/ |archive-date=1 July 2022}}</ref>  Tesla claimed to have developed his own physical principle regarding matter and energy that he started working on in 1892,{{sfn|O'Neill|1944|p=247}} and in 1937, at age 81, claimed in a letter to have completed a "dynamic theory of gravity" that "[would] put an end to idle speculations and false conceptions, as that of curved space". He stated that the theory was "worked out in all details" and that he hoped to soon give it to the world.<ref>[http://www.tesla.hu/tesla/articles/19370710.doc Prepared Statement by Nikola Tesla] {{Webarchive|url=https://web.archive.org/web/20110724105436/http://www.tesla.hu/tesla/articles/19370710.doc |date=24 July 2011 }} downloadable from http://www.tesla.hu {{Webarchive|url=https://web.archive.org/web/20181225022943/http://tesla.hu/ |date=25 December 2018 }}</ref> Further elucidation of his theory was never found in his writings.{{sfn|Cheney|2001|p=309}}

=== On society ===
{{Eugenics sidebar}}

Tesla is widely considered by his biographers to have been a [[Humanism|humanist]] in philosophical outlook.{{sfn|Jonnes|2004|p=154}}<ref>{{cite book |title=Innovation: The Lessons of Nikola Tesla |year=2008 |publisher=Blue Eagle |isbn=978-987-651-009-7 |page=43 |first1=Peter |last1=Belohlavek |first2=John W |last2=Wagner |quote=This was Tesla: a scientist, philosopher, humanist, and ethical man of the world in the truest sense.}}</ref> He expressed the belief that human "pity" had come to interfere with the natural "ruthless workings of nature". Though his argumentation did not depend on a concept of a "master race" or the inherent superiority of one person over another, he advocated for eugenics.<ref>{{cite web |url=https://www.pbs.org/tesla/res/res_art11.html |title=A Machine to End War |date=February 1937 |publisher=Public Broadcasting Service |access-date=23 November 2010 |archive-date=20 January 2022 |archive-url=https://web.archive.org/web/20220120214740/https://www.pbs.org/tesla/res/res_art11.html |url-status=live }}</ref> In 1926, Tesla commented on the ills of the social subservience of women and the struggle of women for [[gender equality]]. He indicated that humanity's future would be run by "[[Queen bee (sociology)|Queen Bees]]". He believed that women would become the dominant sex in the future.<ref>Kennedy, John B., "[http://www.tfcbooks.com/tesla/1926-01-30.htm When woman is boss] {{Webarchive|url=https://web.archive.org/web/20110606023652/http://www.tfcbooks.com/tesla/1926-01-30.htm |date=6 June 2011 }}, An interview with Nikola Tesla." [[Collier's Weekly|Colliers]], 30 January 1926.</ref> He made predictions about the relevant issues of a post-World War I environment in an article entitled "Science and Discovery are the great Forces which will lead to the Consummation of the War" (20 December 1914).<ref>{{cite web |last=Tesla |first=Nikola |title=Science and Discovery are the great Forces which will lead to the Consummation of the War |url=http://www.rastko.rs/rastko/delo/10832 |publisher=Rastko |access-date=17 July 2012 |archive-date=2 April 2015 |archive-url=https://web.archive.org/web/20150402053438/http://www.rastko.rs/rastko/delo/10832 |url-status=live }}</ref>

=== On religion ===
Tesla was raised in the faith of the Eastern Orthodox Church. Later in life he did not consider himself to be a "believer in the orthodox sense", said he opposed [[religious fanaticism]], and said "Buddhism and Christianity are the greatest religions both in number of disciples and in importance."<ref name="Viereck1937">{{cite web |title=A Machine to End War |url=https://www.pbs.org/tesla/res/res_art11.html |publisher=PBS.org |access-date=27 July 2012 |last=Tesla |first=Nikola |editor=George Sylvester Viereck |date=February 1937 |archive-date=20 January 2022 |archive-url=https://web.archive.org/web/20220120214740/https://www.pbs.org/tesla/res/res_art11.html |url-status=live }}</ref> He also said "To me, the universe is simply a great machine which never came into being and never will end" and "what we call 'soul' or 'spirit,' is nothing more than the sum of the functionings of the body. When this functioning ceases, the 'soul' or the 'spirit' ceases likewise."<ref name="Viereck1937" />

== Literary works ==
Tesla wrote a number of books and articles for magazines and journals.<ref>{{cite web |title=Nikola Tesla Bibliography |url=http://www.tfcbooks.com/tesla/bibliography.htm |publisher=21st Century Books |access-date=21 April 2011 |archive-date=27 September 2015 |archive-url=https://web.archive.org/web/20150927044514/http://www.tfcbooks.com/tesla/bibliography.htm |url-status=live }}</ref> Among his books are ''[[My Inventions: The Autobiography of Nikola Tesla]]'', compiled and edited by Ben Johnston in 1983 from a series of 1919 magazine articles by Tesla which were republished in 1977; ''[[The Fantastic Inventions of Nikola Tesla]]'' (1993), compiled and edited by [[David Hatcher Childress]]; and ''The Tesla Papers''. Many of his writings are freely available online,<ref>{{cite web|title=Selected Tesla writings|work=Nikola Tesla Information Resource|url=http://www.tfcbooks.com/tesla/contents.htm|access-date=15 March 2008|archive-url=https://web.archive.org/web/20090130031901/http://tfcbooks.com/tesla/contents.htm|archive-date=30 January 2009|url-status=dead}}</ref> including the article "The Problem of Increasing Human Energy", published in ''The Century Magazine'' in 1900,<ref>{{cite web |title=The problem of increasing human energy |url=http://www.tfcbooks.com/tesla/1900-06-00.htm |publisher=Twenty-First Century Books |access-date=21 April 2011 |archive-date=20 November 2019 |archive-url=https://web.archive.org/web/20191120001402/http://www.tfcbooks.com/tesla/1900-06-00.htm |url-status=live }}</ref> and the article "Experiments with Alternate Currents of High Potential and High Frequency", published in his book ''Inventions, Researches and Writings of Nikola Tesla''.<ref>{{cite book |last=Tesla |first=Nikola |title=The Project Gutenberg eBook, Experiments with Alternate Currents of High Potential and High Frequency, by Nikola Tesla |url=https://www.gutenberg.org/files/13476/13476-h/13476-h.htm |publisher=[[Project Gutenberg]] |access-date=21 April 2011 |archive-date=16 September 2011 |archive-url=https://web.archive.org/web/20110916122641/http://www.gutenberg.org/files/13476/13476-h/13476-h.htm |url-status=live }}</ref><ref>{{cite web |last=Tesla |first=Nikola |title=Experiments with alternate currents of high potential and high frequency |url=http://www.tfcbooks.com/tesla/1892-02-03.htm |publisher=Twenty-First Century Books |access-date=21 April 2011 |archive-date=19 September 2015 |archive-url=https://web.archive.org/web/20150919045738/http://www.tfcbooks.com/tesla/1892-02-03.htm |url-status=live }}</ref>

== Legacy ==
{{See|Nikola Tesla in popular culture|List of things named after Nikola Tesla|List of Nikola Tesla patents}}

[[File:Urn with Teslas ashes.jpg|thumb|Gilded urn with Tesla's ashes, in his favorite geometric object, a [[sphere]] ([[Nikola Tesla Museum]], Belgrade)]]

In 1952, following pressure from Tesla's nephew, Yugoslav politician {{ill|Sava Kosanović|sr|Sava Kosanović (političar)}}, Tesla's entire estate was shipped to Belgrade in 80 trunks marked "N.T.". In 1957, Kosanović's secretary Charlotte Muzar transported Tesla's ashes from the United States to Belgrade. They are displayed in a gold-plated sphere on a marble pedestal in the Nikola Tesla Museum.<ref>{{cite web |title=Urn with Tesla's ashes |url=http://www.tesla-museum.org/meni_en/muzej/3.htm |publisher=Tesla Museum |access-date=16 September 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120825230422/http://www.tesla-museum.org/meni_en/muzej/3.htm |archive-date=25 August 2012 }}</ref> His archive consists of over 160,000 documents and is included in the UNESCO [[Memory of the World Programme]].<ref>{{Cite news |title=Nikola Tesla's Archive |url=https://www.unesco.org/en/memory-world/nikola-teslas-archive |archive-url=http://web.archive.org/web/20241203015718/https://www.unesco.org/en/memory-world/nikola-teslas-archive |archive-date=3 December 2024 |access-date=24 December 2024}}</ref><ref>{{cite web |title=Archive – Nikola Tesla Museum |url=https://tesla-museum.org/en/legacy/archive/ |access-date=24 December 2024}}</ref>

Tesla obtained around 300 patents worldwide for his inventions.<ref name="sarboh">{{cite web |url=http://www.tesla-symp06.org/papers/Tesla-Symp06_Sarboh.pdf |title=Nikola Tesla's Patents |first=Snežana |last=Šarboh |date=18–20 October 2006 |work=Sixth International Symposium Nikola Tesla |location=Belgrade, Serbia |page=6 |archive-url=https://web.archive.org/web/20071030134331/http://www.tesla-symp06.org/papers/Tesla-Symp06_Sarboh.pdf |archive-date=30 October 2007 |access-date=8 October 2010 |ref=sarbo}}</ref> Some of Tesla's patents are not accounted for, and some that have lain hidden in patent archives have been rediscovered. There are at least 278 known patents<ref name="sarboh"/> issued to Tesla in 26 countries. Many were in the United States, [[United Kingdom of Great Britain and Ireland|Britain]], and Canada, but many others were approved in countries around the globe.{{sfn|Cheney|2001|p=62}}

== See also ==
* {{Annotated link|Atmospheric electricity}}
* {{Annotated link|Michael Faraday}}
* {{Annotated link|Charles Proteus Steinmetz}}
* {{Annotated link|Telluric current}}

== Notes ==

=== Footnotes ===
{{Notelist}}
{{Clear}}

=== Citations ===
{{Reflist}}

== References ==
{{Refbegin|30em}}
* {{cite book|last=Carlson|first=W. Bernard|title=Tesla: Inventor of the Electrical Age|url=https://books.google.com/books?id=5I5c9j8BEn4C|year=2013|publisher=[[Princeton University Press]]|isbn=978-1-4008-4655-9|access-date=2 June 2015|archive-date=5 August 2023|archive-url=https://web.archive.org/web/20230805044626/https://books.google.com/books?id=5I5c9j8BEn4C|url-status=live}}
* {{cite book|last=Cheney|first=Margaret|author-link=Margaret Cheney (author)|title=Tesla: Man out of Time|url=https://books.google.com/books?id=HIuK7iLO9zgC|year=2011|publisher=Simon & Schuster|isbn=978-1-4516-7486-6|access-date=13 December 2015|archive-date=23 March 2024|archive-url=https://web.archive.org/web/20240323124618/https://books.google.com/books?id=HIuK7iLO9zgC|url-status=live}}
* {{cite book |last=Cheney |first=Margaret |author-link=Margaret Cheney (author)|title=Tesla: Man out of Time |orig-year=1981 |url=https://books.google.com/books?id=ti2Jt7XarzMC |year=2001 |publisher=[[Simon & Schuster]] |isbn=978-0-7432-1536-7 |access-date=14 May 2020 |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323124620/https://books.google.com/books?id=ti2Jt7XarzMC |url-status=live }}
* {{cite book |last1=Cheney |first1=Margaret|author1-link=Margaret Cheney (author) |last2=Uth |first2=Robert |last3=Glenn |first3=Jim |title=Tesla, Master of Lightning |year=1999 |publisher=[[Barnes & Noble Books]] |isbn=978-0-7607-1005-0 |url=https://books.google.com/books?id=3W6_h6XG6VAC |access-date=21 June 2015 |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323124632/https://books.google.com/books?id=3W6_h6XG6VAC |url-status=live }}
* {{cite book |last1=Cooper |first1=Christopher |title=The truth about Tesla : The myth of the lone genius in the history of innovation |date=2015 |location=New York |isbn=978-1-63106-030-4 |publisher=Race Point Publishing}}
* {{cite book|last=Dommermuth-Costa|first=Carol|title=Nikola Tesla: A Spark of Genius|url=https://books.google.com/books?id=kFFWipanqsoC|year=1994|publisher=[[Twenty-First Century Books]]|isbn=978-0-8225-4920-8|access-date=13 December 2015|archive-date=23 March 2024|archive-url=https://web.archive.org/web/20240323125136/https://books.google.com/books?id=kFFWipanqsoC|url-status=live}}
* {{cite book |last=Jonnes |first=Jill |title=Empires of Light: Edison, Tesla, Westinghouse, and the Race to Electrify the World |year=2004 |publisher=[[Random House]] Trade Paperbacks |isbn=978-0-375-75884-3 |url=https://books.google.com/books?id=BKX5UYWzVyQC |access-date=13 December 2015 |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323125210/https://books.google.com/books?id=BKX5UYWzVyQC |url-status=live }}
* {{cite book|last=Klooster|first=John W.|title=Icons of Invention: The Makers of the Modern World from Gutenberg to Gates|url=https://books.google.com/books?id=WKuG-VIwID8C|year=2009|publisher=[[ABC-CLIO]]|isbn=978-0-313-34743-6|access-date=13 December 2015|archive-date=23 March 2024|archive-url=https://web.archive.org/web/20240323125138/https://books.google.com/books?id=WKuG-VIwID8C|url-status=live}}
* {{cite book |last=O'Neill |first=John J. |author-link=John Joseph O'Neill (journalist) |date=2007 |url=https://www.rastko.rs/istorija/tesla/oniell-tesla.html |title=Prodigal Genius: The Life of Nikola Tesla |orig-date=1944 |location=New York |publisher=Ives Washburn |isbn=978-0-914732-33-4 |access-date=10 July 2024 |archive-date=3 December 2023 |archive-url=https://web.archive.org/web/20231203084239/https://www.rastko.rs/istorija/tesla/oniell-tesla.html |url-status=live |ref=CITEREFO'Neill1944}} (see also ''[[Prodigal Genius: The Life of Nikola Tesla]]''; also {{ISBN|1-59605-713-0}}; reprinted 2007 by Book Tree, {{ISBN|978-1-60206-743-1}})
* {{cite book |last=Pickover |first=Clifford A. |url=https://books.google.com/books?id=P0CSxB2aHMcC |title=Strange Brains and Genius: The Secret Lives of Eccentric Scientists and Madmen |publisher=[[HarperCollins]] |year=1999 |isbn=978-0-688-16894-0 |access-date=13 December 2015 |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323125210/https://books.google.com/books?id=P0CSxB2aHMcC |url-status=live }}
* {{cite book|last1=Petešić|first1=Ćiril|title=Genij s našeg kamenjara: život i djelo Nikole Tesle|trans-title=The genius from our rocks: life and work of Nikola Tesla|year=1976|publisher=Školske novine|location=Zagreb|language=hr|oclc=36439558}}
* {{cite book |last=Seifer |first=Marc J. |title=Wizard: The Life and Times of Nikola Tesla: Biography of a genius |year=2001 |publisher=Citadel |isbn=978-0-8065-1960-9 |url=https://books.google.com/books?id=h2DTNDFcC14C |access-date=13 December 2015 |archive-date=23 March 2024 |archive-url=https://web.archive.org/web/20240323125147/https://books.google.com/books?id=h2DTNDFcC14C |url-status=live }}
* {{cite book|last=Seifer|first=Marc J.|title=Wizard: The Life and Times of Nikola Tesla: Biography of a genius|url=https://books.google.com/books?id=DzMR8x_rbPgC|year=1998|publisher=Citadel|isbn=978-0-8065-3556-2|access-date=16 March 2016|archive-date=23 March 2024|archive-url=https://web.archive.org/web/20240323125351/https://books.google.ro/books?id=DzMR8x_rbPgC&redir_esc=y|url-status=live}}
* {{cite book|last1=Skrabec|first1=Quentin R.|title=George Westinghouse: Gentle Genius|date=2007|publisher=Algora Publishing|location=New York|isbn=978-0-87586-506-5}}
* {{cite book |last=Van Riper |first=A. Bowdoin |url=https://books.google.com/books?id=ABtJPIcVtBoC |title=A Biographical Encyclopedia of Scientists and Inventors in American Film and TV since 1930 |year=2011 |publisher=Scarecrow Press |isbn=978-0-8108-8128-0 }}
* {{cite book | title = Nikola Tesla and the Graz Tech | editor-first1 = Uwe | editor-last1 = Schichler | editor-first2 = Josef W. | editor-last2 = Wohinz | first = Josef W. | last = Wohinz | chapter = Nikola Tesla: Milestones in his life | publisher = Graz University of Technology/Library and Archive | year = 2019 | doi = 10.3217/978-3-85125-687-1 | volume = 7 EN | isbn = 978-3-85125-688-8 }}
{{Refend}}

== Further reading ==
{{Library resources box|by=yes}}

===Books===
{{Refbegin}}
<!--Keep in alphabetical order by author's surname -->
*{{anchor|Autobiography}} Tesla, Nikola, ''[[My Inventions]],'' Parts I through V published in the ''Electrical Experimenter'' monthly magazine from February through June 1919. Part VI published October 1919. Reprint edition with introductory notes by Ben Johnson, New York: Barnes and Noble, 1982; also online at ''[http://www.lucidcafe.com/library/96jul/teslaauto01.html Lucid Cafe] {{Webarchive|url=https://web.archive.org/web/20160202014045/http://www.lucidcafe.com/library/96jul/teslaauto01.html |date=2 February 2016 }}, [http://www.tfcbooks.com/special/mi_link.htm et cetera] {{Webarchive|url=https://web.archive.org/web/20160126224720/http://www.tfcbooks.com/special/mi_link.htm |date=26 January 2016 }} as [[My Inventions: The Autobiography of Nikola Tesla]]'', 1919. {{ISBN|978-0-910077-00-2}}
* Glenn, Jim (1994). ''The Complete Patents of Nikola Tesla''. {{ISBN|978-1-56619-266-8}}
* [[Robert Lomas|Lomas, Robert]] (1999). ''[[The Man Who Invented the Twentieth Century]]: Nikola Tesla, forgotten genius of electricity''. London: Headline. {{ISBN|978-0-7472-7588-6}}
* [[Thomas Commerford Martin|Martin, Thomas C. (editor)]] (1894, 1996 reprint, copyright expired), ''[[The Inventions, Researches, and Writings of Nikola Tesla]]'', includes some lectures, Montana: Kessinger. {{ISBN|978-1-56459-711-3}}
* {{cite book |last1=Peat |first1=F. David|author-link1=F. David Peat |title=[[In Search of Nikola Tesla]] |date=2002 |publisher=Ashgrove |location=Bath |isbn=978-1-85398-117-3 |edition=Revised}}
* Trinkaus, George (2002). ''Tesla: The Lost Inventions'', High Voltage Press. {{ISBN|978-0-9709618-2-2}}
* Valone, Thomas (2002). ''Harnessing the Wheelwork of Nature: Tesla's Science of Energy''. {{ISBN|978-1-931882-04-0}}
{{Refend}}

===Publications===
{{Refbegin|40em}}
* ''[[s:A New System of Alternating Current Motors and Transformers|A New System of Alternating Current Motors and Transformers]]'', American Institute of Electrical Engineers, May 1888.
* ''[https://web.archive.org/web/20090130031901/http://tfcbooks.com/tesla/contents.htm Selected Tesla Writings]'', Scientific papers and articles written by Tesla and others, spanning the years 1888–1940.
* ''[https://cdl.library.cornell.edu/cgi-bin/moa/pageviewer?frames=1&coll=moa&view=50&root=%2Fmoa%2Fmanu%2Fmanu0024%2F&tif=00119.TIF&cite=http%3A%2F%2Fcdl.library.cornell.edu%2Fcgi-bin%2Fmoa%2Fmoa-cgi%3Fnotisid%3DABS1821-0024-287 Light Without Heat] {{Webarchive|url=https://web.archive.org/web/20220316114143/http://collections.library.cornell.edu/moa_new/browse.html?frames=1&coll=moa&view=50&root=%2Fmoa%2Fmanu%2Fmanu0024%2F&tif=00119.TIF&cite=http%3A%2F%2Fcdl.library.cornell.edu%2Fcgi-bin%2Fmoa%2Fmoa-cgi%3Fnotisid%3DABS1821-0024-287 |date=16 March 2022 }}'', The Manufacturer and Builder, January 1892, Vol. 24
* Biography: ''[https://cdl.library.cornell.edu/cgi-bin/moa/pageviewer?frames=1&coll=moa&view=50&root=%2Fmoa%2Fcent%2Fcent0047%2F&tif=00592.TIF&cite=http%3A%2F%2Fcdl.library.cornell.edu%2Fcgi-bin%2Fmoa%2Fmoa-cgi%3Fnotisid%3DABP2287-0047-151 Nikola Tesla] {{Webarchive|url=https://web.archive.org/web/20060509050052/http://cdl.library.cornell.edu/cgi-bin/moa/pageviewer?frames=1&coll=moa&view=50&root=%2Fmoa%2Fcent%2Fcent0047%2F&tif=00592.TIF&cite=http%3A%2F%2Fcdl.library.cornell.edu%2Fcgi-bin%2Fmoa%2Fmoa-cgi%3Fnotisid%3DABP2287-0047-151 |date=9 May 2006 }}'', The Century Magazine, November 1893, Vol. 47
* ''[https://cdl.library.cornell.edu/cgi-bin/moa/pageviewer?frames=1&coll=moa&view=50&root=%2Fmoa%2Fcent%2Fcent0049%2F&tif=00924.TIF&cite=http%3A%2F%2Fcdl.library.cornell.edu%2Fcgi-bin%2Fmoa%2Fmoa-cgi%3Fnotisid%3DABP2287-0049-178 Tesla's Oscillator and Other Inventions] {{Webarchive|url=https://web.archive.org/web/20060509050030/http://cdl.library.cornell.edu/cgi-bin/moa/pageviewer?frames=1&coll=moa&view=50&root=%2Fmoa%2Fcent%2Fcent0049%2F&tif=00924.TIF&cite=http%3A%2F%2Fcdl.library.cornell.edu%2Fcgi-bin%2Fmoa%2Fmoa-cgi%3Fnotisid%3DABP2287-0049-178 |date=9 May 2006 }}'', The Century Magazine, November 1894, Vol. 49
* ''[https://cdl.library.cornell.edu/cgi-bin/moa/pageviewer?frames=1&coll=moa&view=50&root=%2Fmoa%2Fcent%2Fcent0055%2F&tif=00879.TIF&cite=http%3A%2F%2Fcdl.library.cornell.edu%2Fcgi-bin%2Fmoa%2Fmoa-cgi%3Fnotisid%3DABP2287-0055-194 The New Telegraphy. Recent Experiments in Telegraphy with Sparks] {{Webarchive|url=https://web.archive.org/web/20220316114143/http://collections.library.cornell.edu/moa_new/browse.html?frames=1&coll=moa&view=50&root=%2Fmoa%2Fcent%2Fcent0055%2F&tif=00879.TIF&cite=http%3A%2F%2Fcdl.library.cornell.edu%2Fcgi-bin%2Fmoa%2Fmoa-cgi%3Fnotisid%3DABP2287-0055-194 |date=16 March 2022 }}'', The Century Magazine, November 1897, Vol. 55
{{Refend}}

===Journals===
{{Refbegin|40em}}
* {{cite journal|last=Pavićević |first=Aleksandra|title=From lighting to dust death, funeral and post mortem destiny of Nikola Tesla|journal=Glasnik Etnografskog instituta SANU|year=2014|volume=62|issue=2|pages=125–139|url=http://www.doiserbia.nb.rs/ft.aspx?id=0350-08611402125P|doi=10.2298/GEI1402125P|doi-access=free|hdl=21.15107/rcub_dais_8218|hdl-access=free| issn = 0350-0861 }}
* Carlson, W. Bernard, "Inventor of dreams". ''[[Scientific American]]'', March 2005 Vol. 292 Issue 3 p.&nbsp;78(7).
* Lawren, B., "Rediscovering Tesla". ''[[Omni (magazine)|Omni]]'', March 1988, Vol. 10 Issue 6.
* Thibault, Ghislain, "The Automatization of Nikola Tesla: Thinking Invention in the Late Nineteenth Century". ''[https://muse.jhu.edu/article/519919 Configurations] {{Webarchive|url=https://web.archive.org/web/20180328103312/https://muse.jhu.edu/article/519919 |date=28 March 2018 }}'', Volume 21, Number 1, Winter 2013, pp.&nbsp;27–52.
* [[Thomas Commerford Martin|Martin, Thomas Commerford]], "The Inventions, Researches, and Writings of Nikola Tesla", New York: The Electrical Engineer, 1894 (3rd Ed.); reprinted by Barnes & Noble, 1995
* [[Anil K. Rajvanshi]], [https://web.archive.org/web/20150109004451/http://www.ias.ac.in/resonance/Volumes/12/03/0004-0012.pdf "Nikola Tesla&nbsp;– The Creator of Electric Age"], ''Resonance'', March 2007.
* Roguin, Ariel, "Historical Note: Nikola Tesla: The man behind the magnetic field unit". J. Magn. Reson. Imaging 2004;19:369–374. 2004 Wiley-Liss, Inc.
* Sellon, J. L., "The impact of Nikola Tesla on the cement industry". Behrent Eng. Co., Wheat Ridge, Colorado. Cement Industry Technical Conference. 1997. XXXIX Conference Record., 1997 IEEE/PC. Page(s) 125–133.
* Valentinuzzi, M.E., "Nikola Tesla: why was he so much resisted and forgotten?" Inst. de Bioingenieria, Univ. Nacional de Tucuman; Engineering in Medicine and Biology Magazine, IEEE. July/August 1998, 17:4, pp.&nbsp;74–75.
* Secor, H. Winfield, "Tesla's views on Electricity and the War", Electrical Experimenter, Volume 5, Number 4 August 1917.
* Florey, Glen, "Tesla and the Military". ''Engineering'' 24, 5 December 2000.
* Corum, K. L., J. F. Corum, ''Nikola Tesla, Lightning Observations, and Stationary Waves''. 1994.
* Corum, K. L., J. F. Corum, and A. H. Aidinejad, ''Atmospheric Fields, Tesla's Receivers and Regenerative Detectors''. 1994.
* Meyl, Konstantin, H. Weidner, E. Zentgraf, T. Senkel, T. Junker, and P. Winkels, ''Experiments to proof the evidence of scalar waves Tests with a Tesla reproduction''. Institut für Gravitationsforschung (IGF), Am Heerbach 5, D-63857 Waldaschaff.
* Anderson, L. I., "John Stone Stone on Nikola Tesla's Priority in Radio and Continuous Wave Radiofrequency Apparatus". [[The AWA Review]], Vol. 1, 1986, pp.&nbsp;18–41.
* Anderson, L. I., "Priority in Invention of Radio, Tesla v. Marconi". Antique Wireless Association monograph, March 1980.
* Marincic, A., and D. Budimir, "Tesla's contribution to radiowave propagation". Dept. of Electron. Eng., Belgrade Univ. (5th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Service, 2001. TELSIKS 2001. pp.&nbsp;327–331 vol.1)
{{Refend}}

== External links ==
{{External media | float = right | video1 = [https://www.c-span.org/video/?178806-1/empires-light-edison-tesla-westinghouse ''Booknotes'' interview with Jill Jonnes on ''Empires of Light'', 26 October 2003], [[C-SPAN]]}}
{{Sister project links|commons=Category:Nikola Tesla|wikt=no|n=no|v=no|s=Author:Nikola Tesla}}
{{Spoken Wikipedia|date=19 June 2021|En-Nikola Tesla 1of2-article.ogg|En-Nikola Tesla 2of2-article.ogg}}
* [http://www.teslamemorialsociety.org/ Tesla memorial society by his grand-nephew William H. Terbo]
* {{cite journal|author=FBI|title=Nikola Tesla|journal=Main Investigative File|publisher=FBI|url=http://www.lostartsmedia.com/images/teslafbifile.pdf}}
* [https://teslasciencecenter.org/ Tesla Science Center at Wardenclyffe]
* {{Gutenberg author |id=5067| name=Nikola Tesla}}
* {{Internet Archive author |sname=Nikola Tesla}}
* {{Librivox author |id=11695}}
* [https://nautil.us/teslas-pigeon-460446 "Tesla's pigeon"] – Amanda Gefter

{{Nikola Tesla}}
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