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Available in 20 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-20" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">20 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D9%87%D8%A7%D8%AA%D9%81_%D8%B6%D9%88%D8%A6%D9%8A" title="هاتف ضوئي – Arabic" lang="ar" hreflang="ar" data-title="هاتف ضوئي" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Fot%C3%B2fon" title="Fotòfon – Catalan" lang="ca" hreflang="ca" data-title="Fotòfon" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Fotofon" title="Fotofon – Czech" lang="cs" hreflang="cs" data-title="Fotofon" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Photophon" title="Photophon – German" lang="de" hreflang="de" data-title="Photophon" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Fot%C3%B3fono" title="Fotófono – Spanish" lang="es" hreflang="es" data-title="Fotófono" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D9%81%D9%88%D8%AA%D9%88%D9%81%D9%88%D9%86" title="فوتوفون – Persian" lang="fa" hreflang="fa" data-title="فوتوفون" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Photophone_(t%C3%A9l%C3%A9phonie_optique)" title="Photophone (téléphonie optique) – French" lang="fr" hreflang="fr" data-title="Photophone (téléphonie optique)" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EA%B4%91%EC%84%A0%EC%A0%84%ED%99%94" title="광선전화 – Korean" lang="ko" hreflang="ko" data-title="광선전화" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D5%96%D5%B8%D5%BF%D5%B8%D6%86%D5%B8%D5%B6" title="Ֆոտոֆոն – Armenian" lang="hy" hreflang="hy" data-title="Ֆոտոֆոն" data-language-autonym="Հայերեն" data-language-local-name="Armenian" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Fotofono" title="Fotofono – Italian" lang="it" hreflang="it" data-title="Fotofono" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%A4%D7%95%D7%98%D7%95%D7%A4%D7%95%D7%9F" title="פוטופון – Hebrew" lang="he" hreflang="he" data-title="פוטופון" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Fotofoon" title="Fotofoon – Dutch" lang="nl" hreflang="nl" data-title="Fotofoon" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E3%83%95%E3%82%A9%E3%83%88%E3%83%95%E3%82%A9%E3%83%B3" title="フォトフォン – Japanese" lang="ja" hreflang="ja" data-title="フォトフォン" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Fotofon" title="Fotofon – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="Fotofon" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Photophone" title="Photophone – Portuguese" lang="pt" hreflang="pt" data-title="Photophone" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%A4%D0%BE%D1%82%D0%BE%D1%84%D0%BE%D0%BD" title="Фотофон – Russian" lang="ru" hreflang="ru" data-title="Фотофон" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Photophone" title="Photophone – Simple English" lang="en-simple" hreflang="en-simple" data-title="Photophone" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Valopuhelin" title="Valopuhelin – Finnish" lang="fi" hreflang="fi" data-title="Valopuhelin" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%A4%D0%BE%D1%82%D0%BE%D1%84%D0%BE%D0%BD" title="Фотофон – Ukrainian" lang="uk" hreflang="uk" data-title="Фотофон" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li 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</nav> <nav class="vector-appearance-landmark" aria-label="Appearance"> <div id="vector-appearance-pinned-container" class="vector-pinned-container"> <div id="vector-appearance" class="vector-appearance vector-pinnable-element"> <div class="vector-pinnable-header vector-appearance-pinnable-header vector-pinnable-header-pinned" data-feature-name="appearance-pinned" data-pinnable-element-id="vector-appearance" data-pinned-container-id="vector-appearance-pinned-container" data-unpinned-container-id="vector-appearance-unpinned-container" > <div class="vector-pinnable-header-label">Appearance</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-appearance.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-appearance.unpin">hide</button> </div> </div> </div> </nav> </div> </div> <div id="bodyContent" class="vector-body" aria-labelledby="firstHeading" data-mw-ve-target-container> <div class="vector-body-before-content"> <div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Device that uses light to transmit speech</div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">Not to be confused with <a href="/wiki/Videotelephony" title="Videotelephony">Videotelephony</a>.</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">This article is about Alexander Graham Bell and Sumner Tainter's optical phone. For the sound-on-film technology, see <a href="/wiki/RCA_Photophone" title="RCA Photophone">RCA Photophone</a>.</div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Photophone_plaque_(no_copyright_applies).jpg" class="mw-file-description"><img alt="An image of darkened brass historical plaque with a streak of green corrosion running down it, mounted on the exterior side of a brick building." src="//upload.wikimedia.org/wikipedia/commons/thumb/9/98/Photophone_plaque_%28no_copyright_applies%29.jpg/220px-Photophone_plaque_%28no_copyright_applies%29.jpg" decoding="async" width="220" height="150" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/98/Photophone_plaque_%28no_copyright_applies%29.jpg/330px-Photophone_plaque_%28no_copyright_applies%29.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/98/Photophone_plaque_%28no_copyright_applies%29.jpg/440px-Photophone_plaque_%28no_copyright_applies%29.jpg 2x" data-file-width="641" data-file-height="438" /></a><figcaption>A historical plaque on the side of the Franklin School in Washington, D.C. which marks one of the points from which the photophone was demonstrated</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Bells_Photophon_Schema.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/78/Bells_Photophon_Schema.jpg/220px-Bells_Photophon_Schema.jpg" decoding="async" width="220" height="136" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/78/Bells_Photophon_Schema.jpg/330px-Bells_Photophon_Schema.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/78/Bells_Photophon_Schema.jpg/440px-Bells_Photophon_Schema.jpg 2x" data-file-width="640" data-file-height="396" /></a><figcaption>A diagram from one of Bell's 1880 papers</figcaption></figure> <p>The <b>photophone</b> is a <a href="/wiki/Telecommunications" title="Telecommunications">telecommunications</a> device that allows <a href="/wiki/Transmission_(telecommunications)" class="mw-redirect" title="Transmission (telecommunications)">transmission</a> of speech on a beam of <a href="/wiki/Light" title="Light">light</a>. It was invented jointly by <a href="/wiki/Alexander_Graham_Bell" title="Alexander Graham Bell">Alexander Graham Bell</a> and his assistant <a href="/wiki/Charles_Sumner_Tainter" title="Charles Sumner Tainter">Charles Sumner Tainter</a> on February 19, 1880, at Bell's laboratory at 1325 L Street in Washington, D.C.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-SDU_2-0" class="reference"><a href="#cite_note-SDU-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> Both were later to become full associates in the <a href="/wiki/Volta_Laboratory_and_Bureau#Laboratory_projects" title="Volta Laboratory and Bureau">Volta Laboratory Association</a>, created and financed by Bell. </p><p>On June 3, 1880, Bell's assistant transmitted a wireless voice telephone message from the roof of the <a href="/wiki/Franklin_School_(Washington,_D.C.)" title="Franklin School (Washington, D.C.)">Franklin School</a> to the window of Bell's laboratory, some 213 meters (about 700 ft.) away.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Carson_2007,_pg._76–78_4-0" class="reference"><a href="#cite_note-Carson_2007,_pg._76–78-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Groth_5-0" class="reference"><a href="#cite_note-Groth-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Mims_1982,_p._11_6-0" class="reference"><a href="#cite_note-Mims_1982,_p._11-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p><p>Bell believed the photophone was his most important <a href="/wiki/Invention" title="Invention">invention</a>. Of the 18 <a href="/wiki/Patent" title="Patent">patents</a> granted in Bell's name alone, and the 12 he shared with his collaborators, four were for the photophone, which Bell referred to as his "greatest achievement", telling a reporter shortly before his death that the photophone was "the greatest invention [I have] ever made, greater than the telephone".<sup id="cite_ref-Phillipson+Neilson_7-0" class="reference"><a href="#cite_note-Phillipson+Neilson-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Mims_1982,_p._14_8-0" class="reference"><a href="#cite_note-Mims_1982,_p._14-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p><p>The photophone was a precursor to the <a href="/wiki/Fiber-optic_communication" title="Fiber-optic communication">fiber-optic communication</a> systems that achieved worldwide popular usage starting in the 1980s.<sup id="cite_ref-Morgan_9-0" class="reference"><a href="#cite_note-Morgan-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-AmericanScientist-1984.V72.No1_10-0" class="reference"><a href="#cite_note-AmericanScientist-1984.V72.No1-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Gallardo+Mims_11-0" class="reference"><a href="#cite_note-Gallardo+Mims-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> The master patent for the photophone (<span><a rel="nofollow" class="external text" href="https://patents.google.com/patent/US235199">U.S. patent 235,199</a></span> <i>Apparatus for Signalling and Communicating, called Photophone</i>) was issued in December 1880,<sup id="cite_ref-Groth_5-1" class="reference"><a href="#cite_note-Groth-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> many decades before its principles came to have practical applications. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Design">Design</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photophone&action=edit&section=1" title="Edit section: Design"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Photophony1.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/9d/Photophony1.jpg/220px-Photophony1.jpg" decoding="async" width="220" height="146" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/9d/Photophony1.jpg/330px-Photophony1.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/9d/Photophony1.jpg/440px-Photophony1.jpg 2x" data-file-width="577" data-file-height="384" /></a><figcaption>A photophone receiver and headset, one half of Bell and Tainter's optical telecommunication system of 1880</figcaption></figure> <p>The photophone was similar to a contemporary telephone, except that it used <a href="/wiki/Free-space_optical_communication#Visible_light_communication" title="Free-space optical communication">modulated light</a> as a means of wireless transmission while the telephone relied on <a href="/wiki/Modulation" title="Modulation">modulated</a> <a href="/wiki/Electricity" title="Electricity">electricity</a> carried over a conductive <a href="/wiki/Two-wire_circuit" title="Two-wire circuit">wire circuit</a>. </p><p>Bell's own description of the light modulator:<sup id="cite_ref-Clark_12-0" class="reference"><a href="#cite_note-Clark-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> </p> <style data-mw-deduplicate="TemplateStyles:r1244412712">.mw-parser-output .templatequote{overflow:hidden;margin:1em 0;padding:0 32px}.mw-parser-output .templatequotecite{line-height:1.5em;text-align:left;margin-top:0}@media(min-width:500px){.mw-parser-output .templatequotecite{padding-left:1.6em}}</style><blockquote class="templatequote"><p> We have found that the simplest form of apparatus for producing the effect consists of a plane mirror of flexible material against the back of which the speaker's voice is directed. Under the action of the voice the mirror becomes alternately convex and concave and thus alternately scatters and condenses the light.</p></blockquote> <p>The brightness of a reflected beam of light, as observed from the location of the receiver, therefore varied in accordance with the audio-frequency variations in air pressure—the sound waves—which acted upon the mirror. </p><p>In its initial form, the photophone receiver was also non-electronic, using the <a href="/wiki/Photoacoustic_effect" title="Photoacoustic effect">photoacoustic effect</a>. Bell found that many substances could be used as direct light-to-sound transducers. <a href="/wiki/Lampblack" class="mw-redirect" title="Lampblack">Lampblack</a> proved to be outstanding. Using a fully modulated beam of sunlight as a test signal, one experimental receiver design, employing only a deposit of lampblack, produced a tone that Bell described as "painfully loud" to an ear pressed close to the device.<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> </p><p>In its ultimate electronic form, the photophone receiver used a simple <a href="/wiki/Selenium#Other_uses" title="Selenium">selenium cell</a> <a href="/wiki/Photodetector" title="Photodetector">photodetector</a> at the <a href="/wiki/Focus_(optics)" title="Focus (optics)">focus</a> of a parabolic mirror.<sup id="cite_ref-Groth_5-2" class="reference"><a href="#cite_note-Groth-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> The cell's <a href="/wiki/Electrical_resistance" class="mw-redirect" title="Electrical resistance">electrical resistance</a> (between about 100 and 300 <a href="/wiki/Ohm" title="Ohm">ohms</a>) varied inversely with the light falling upon it, i.e., its resistance was higher when dimly lit, lower when brightly lit. The selenium cell took the place of a carbon microphone—also a variable-resistance device—in the circuit of what was otherwise essentially an ordinary telephone, consisting of a battery, an electromagnetic earphone, and the variable resistance, all connected in series. The selenium modulated the current flowing through the circuit, and the current was converted back into variations of air pressure—sound—by the earphone. </p><p>In his speech to the American Association for the Advancement of Science in August 1880, Bell gave credit for the first demonstration of speech transmission by light to Mr. A.C. Brown of London in the Fall of 1878.<sup id="cite_ref-Groth_5-3" class="reference"><a href="#cite_note-Groth-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Bell_14-0" class="reference"><a href="#cite_note-Bell-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </p><p><span class="anchor" id="Radiophone"></span>Because the device used <a href="/wiki/Radiant_energy" title="Radiant energy">radiant energy</a>, the French scientist <a href="https://fr.wikipedia.org/wiki/Ernest_Mercadier" class="extiw" title="fr:Ernest Mercadier">Ernest Mercadier</a> suggested that the invention should not be named 'photophone', but 'radiophone', as its mirrors reflected the Sun's radiant energy in multiple bands including the invisible <a href="/wiki/Infrared" title="Infrared">infrared band</a>.<sup id="cite_ref-Grosvenor_&_Wesson_15-0" class="reference"><a href="#cite_note-Grosvenor_&_Wesson-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> Bell used the name for a while but it should not be confused with the later invention "<a href="/wiki/Radiophone" class="mw-redirect" title="Radiophone">radiophone</a>" which used <a href="/wiki/Radio_wave" title="Radio wave">radio waves</a>.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="First_successful_wireless_voice_communications">First successful wireless voice communications</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photophone&action=edit&section=2" title="Edit section: First successful wireless voice communications"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Photophone_transmitter_4074931746_9f996df841_b.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/95/Photophone_transmitter_4074931746_9f996df841_b.jpg/220px-Photophone_transmitter_4074931746_9f996df841_b.jpg" decoding="async" width="220" height="162" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/95/Photophone_transmitter_4074931746_9f996df841_b.jpg/330px-Photophone_transmitter_4074931746_9f996df841_b.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/95/Photophone_transmitter_4074931746_9f996df841_b.jpg/440px-Photophone_transmitter_4074931746_9f996df841_b.jpg 2x" data-file-width="1024" data-file-height="756" /></a><figcaption>Illustration of a photophone transmitter, showing the path of reflected sunlight, before and after being modulated</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Photophone_receiver_4074172975_288f2808f0_o.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4f/Photophone_receiver_4074172975_288f2808f0_o.jpg/220px-Photophone_receiver_4074172975_288f2808f0_o.jpg" decoding="async" width="220" height="336" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4f/Photophone_receiver_4074172975_288f2808f0_o.jpg/330px-Photophone_receiver_4074172975_288f2808f0_o.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4f/Photophone_receiver_4074172975_288f2808f0_o.jpg/440px-Photophone_receiver_4074172975_288f2808f0_o.jpg 2x" data-file-width="814" data-file-height="1243" /></a><figcaption>Illustration of a photophone receiver, depicting the conversion of modulated light to sound, as well as its electrical power source (P)</figcaption></figure> <p>While honeymooning in Europe with his bride <a href="/wiki/Mabel_Gardiner_Hubbard" title="Mabel Gardiner Hubbard">Mabel Hubbard</a>, Bell likely read of the newly discovered property of selenium having a variable resistance when acted upon by light, in a paper by Robert Sabine as published in <i>Nature</i> on 25 April 1878. In his experiments, Sabine used a meter to see the effects of light acting on selenium connected in a circuit to a battery. However Bell reasoned that by adding a telephone receiver to the same circuit he would be able to hear what Sabine could only see.<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> </p><p>As Bell's former associate, <a href="/wiki/Thomas_A._Watson" title="Thomas A. Watson">Thomas Watson</a>, was fully occupied as the superintendent of manufacturing for the nascent <a href="/wiki/Bell_Telephone_Company" title="Bell Telephone Company">Bell Telephone Company</a> back in Boston, Massachusetts, Bell hired <a href="/wiki/Charles_Sumner_Tainter" title="Charles Sumner Tainter">Charles Sumner Tainter</a>, an instrument maker who had previously been assigned to the <a href="/wiki/Transit_of_Venus,_1874" class="mw-redirect" title="Transit of Venus, 1874">U.S. 1874 Transit of Venus Commission</a>, for his new <a href="/wiki/Volta_Laboratory_and_Bureau" title="Volta Laboratory and Bureau">'L' Street laboratory in Washington</a>, at the rate of $15 per week.<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> </p><p>On February 19, 1880, the pair had managed to make a functional photophone in their new laboratory by attaching a set of metallic gratings to a diaphragm, with a beam of light being interrupted by the gratings movement in response to spoken sounds. When the modulated light beam fell upon their selenium receiver Bell, on his headphones, was able to clearly hear Tainter singing <i>Auld Lang Syne</i>.<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> </p><p>In an April 1, 1880, <a href="/wiki/Washington,_D.C." title="Washington, D.C.">Washington, D.C.</a>, experiment, Bell and Tainter communicated some 79 metres (259 ft) along an alleyway to the laboratory's rear window. Then a few months later on June 21 they succeeded in communicating clearly over a distance of some 213 meters (about 700 ft.), using plain <a href="/wiki/Sunlight" title="Sunlight">sunlight</a> as their light source, <a href="/wiki/Incandescent_light_bulb#History_of_the_light_bulb" title="Incandescent light bulb">practical electrical lighting</a> having only just been introduced to the U.S. by <a href="/wiki/Thomas_Edison" title="Thomas Edison">Edison</a>. The transmitter in their latter experiments had sunlight reflected off the surface of a very thin mirror positioned at the end of a speaking tube; as words were spoken they cause the mirror to oscillate between convex and concave, altering the amount of light reflected from its surface to the receiver. Tainter, who was on the roof of the <a href="/wiki/Franklin_School_(Washington,_D.C.)" title="Franklin School (Washington, D.C.)">Franklin School</a>, spoke to Bell, who was in his laboratory listening and who signaled back to Tainter by waving his hat vigorously from the window, as had been requested.<sup id="cite_ref-Mims_1982,_p._11_6-1" class="reference"><a href="#cite_note-Mims_1982,_p._11-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p><p>The receiver was a <a href="/wiki/Parabolic_reflector" title="Parabolic reflector">parabolic mirror</a> with <a href="/wiki/Selenium#Other_uses" title="Selenium">selenium cells</a> at its focal point.<sup id="cite_ref-Groth_5-4" class="reference"><a href="#cite_note-Groth-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> Conducted from the roof of the Franklin School to Bell's laboratory at 1325 'L' Street, this was the world's first formal wireless telephone communication (away from their laboratory), thus making the photophone the world's earliest known voice <a href="/wiki/Wireless_telephone_(disambiguation)" class="mw-redirect mw-disambig" title="Wireless telephone (disambiguation)">wireless telephone</a> system, <sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (February 2017)">citation needed</span></a></i>]</sup> at least 19 years ahead of the first spoken radio wave transmissions. Before Bell and Tainter had concluded their research in order to move on to the development of the <a href="/wiki/Graphophone" title="Graphophone">Graphophone</a>, they had devised some 50 different methods of modulating and demodulating light beams for optical telephony.<sup id="cite_ref-Mims_1982,_p._12_20-0" class="reference"><a href="#cite_note-Mims_1982,_p._12-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Reception_and_adoption">Reception and adoption</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photophone&action=edit&section=3" title="Edit section: Reception and adoption"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The telephone itself was still something of a novelty, and <a href="/wiki/Radio" title="Radio">radio</a> was decades away from commercialization. The social resistance to the photophone's futuristic form of communications could be seen in an August 1880 <i><a href="/wiki/New_York_Times" class="mw-redirect" title="New York Times">New York Times</a></i> commentary:<sup id="cite_ref-NYT-18800830_21-0" class="reference"><a href="#cite_note-NYT-18800830-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> </p> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1244412712"><blockquote class="templatequote"><p>The ordinary man ... will find a little difficulty in comprehending how sunbeams are to be used. Does Prof. Bell intend to connect Boston and Cambridge ... with a line of sunbeams hung on <a href="/wiki/Utility_pole" title="Utility pole">telegraph posts</a>, and, if so, what diameter are the sunbeams to be ....[and] will it be necessary to insulate them against the weather ... until (the public) sees a man going through the streets with a coil of No. 12 sunbeams on his shoulder, and suspending them from pole to pole, there will be a general feeling that there is something about Professor Bell's photophone which places a tremendous strain on human credulity.</p></blockquote> <p>However at the time of their February 1880 breakthrough, Bell was immensely proud of the achievement, to the point that he wanted to name his new second daughter "Photophone", which was subtly discouraged by his wife <a href="/wiki/Mabel_Gardiner_Hubbard" title="Mabel Gardiner Hubbard">Mabel Bell</a> (they instead chose "Marian", with "Daisy" as her <a href="/wiki/Nickname" title="Nickname">nickname</a>).<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> He wrote somewhat enthusiastically:<sup id="cite_ref-Carson_2007,_pg._76–78_4-1" class="reference"><a href="#cite_note-Carson_2007,_pg._76–78-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Bruce_1990,_pg.337_24-0" class="reference"><a href="#cite_note-Bruce_1990,_pg.337-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> </p> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1244412712"><blockquote class="templatequote"><p>I have heard articulate speech by sunlight! I have heard a ray of the sun laugh and cough and sing! ...I have been able to hear a shadow and I have even perceived by ear the passage of a cloud across the sun's disk. You are the grandfather of the Photophone and I want to share my delight at my success.</p><div class="templatequotecite">— <cite><a href="/wiki/Alexander_Graham_Bell" title="Alexander Graham Bell">Alexander Graham Bell</a>, in a letter to his father <a href="/wiki/Alexander_Melville_Bell" title="Alexander Melville Bell">Alexander Melville Bell</a>, dated February 26, 1880</cite></div></blockquote> <p>Bell transferred the photophone's <a href="/wiki/Intellectual_property" title="Intellectual property">intellectual property</a> rights to the <a href="/wiki/Bell_Telephone_Company" title="Bell Telephone Company">American Bell Telephone Company</a> in May 1880.<sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> While Bell had hoped his new photophone could be used by ships at sea and to also displace the plethora of telephone lines that were blooming along busy city boulevards,<sup id="cite_ref-NS-1984.01.12_26-0" class="reference"><a href="#cite_note-NS-1984.01.12-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> his design failed to protect its transmissions from <a href="/wiki/Precipitation_(meteorology)" class="mw-redirect" title="Precipitation (meteorology)">outdoor interferences</a> such as clouds, fog, rain, snow and such, that could easily disrupt the transmission of light.<sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> Factors such as the weather and the lack of light inhibited the use of Bell's invention.<sup id="cite_ref-28" class="reference"><a href="#cite_note-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> Not long after its invention laboratories within the <a href="/wiki/Bell_System" title="Bell System">Bell System</a> continued to improve the photophone in the hope that it could supplement or replace expensive conventional <a href="/wiki/Telephone_line" title="Telephone line">telephone lines</a>. Its earliest non-experimental use came with military communication systems during World War I and II, its key advantage being that its light-based transmissions could not be intercepted by the enemy. </p><p>Bell pondered the photophone's possible scientific use in the <a href="/wiki/Spectroscopy" title="Spectroscopy">spectral analysis</a> of artificial light sources, <a href="/wiki/Star" title="Star">stars</a> and <a href="/wiki/Sunspot" title="Sunspot">sunspots</a>. He later also speculated on its possible future applications, though he did not anticipate either the <a href="/wiki/Laser" title="Laser">laser</a> or <a href="/wiki/Fiber-optic_communication" title="Fiber-optic communication">fiber-optic telecommunications</a>:<sup id="cite_ref-Bruce_1990,_pg.337_24-1" class="reference"><a href="#cite_note-Bruce_1990,_pg.337-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> </p> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1244412712"><blockquote class="templatequote"><p>Can Imagination picture what the future of this invention is to be!.... We may talk by light to any visible distance without any conduction wire.... In general science, discoveries will be make by the Photophone that are undreamed of just now.</p></blockquote> <div class="mw-heading mw-heading2"><h2 id="Further_development">Further development</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photophone&action=edit&section=4" title="Edit section: Further development"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Ernst_Ruhmer,_Technical_World_cover_(1905).jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/05/Ernst_Ruhmer%2C_Technical_World_cover_%281905%29.jpg/200px-Ernst_Ruhmer%2C_Technical_World_cover_%281905%29.jpg" decoding="async" width="200" height="303" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/05/Ernst_Ruhmer%2C_Technical_World_cover_%281905%29.jpg/300px-Ernst_Ruhmer%2C_Technical_World_cover_%281905%29.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/0/05/Ernst_Ruhmer%2C_Technical_World_cover_%281905%29.jpg 2x" data-file-width="332" data-file-height="503" /></a><figcaption>Ernst Ruhmer at his "photo-electric" optical telephone system station. (1905)<sup id="cite_ref-29" class="reference"><a href="#cite_note-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup></figcaption></figure> <p>Although Bell Telephone researchers made several modest incremental improvements on Bell and Tainter's design, <a href="/wiki/Guglielmo_Marconi#Radio_work" title="Guglielmo Marconi">Marconi's radio transmissions</a> started to far surpass the maximum range of the photophone as early as 1897<sup id="cite_ref-Mims_1982,_p._14_8-1" class="reference"><a href="#cite_note-Mims_1982,_p._14-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> and further development of the photophone was largely arrested until German-Austrian experiments began at the turn of the 20th century. </p><p>The German physicist <a href="/wiki/Ernst_Ruhmer" title="Ernst Ruhmer">Ernst Ruhmer</a> believed that the increased sensitivity of his improved selenium cells, combined with the superior receiving capabilities of professor H. T. Simon's "speaking arc", would make the photophone practical over longer signalling distances. Ruhmer carried out a series of experimental transmissions along the <a href="/wiki/Havel" title="Havel">Havel river</a> and on Lake Wannsee from 1901 to 1902. He reported achieving sending distances under good conditions of 15 kilometers (9 miles),<sup id="cite_ref-30" class="reference"><a href="#cite_note-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> with equal success during the day and at night. He continued his experiments around Berlin through 1904, in conjunction with the German Navy, which supplied high-powered searchlights for use in the transmissions.<sup id="cite_ref-31" class="reference"><a href="#cite_note-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> </p><p>The German <a href="/wiki/Siemens_%26_Halske" title="Siemens & Halske">Siemens & Halske Company</a> boosted the photophone's range by utilizing current-modulated carbon arc lamps which provided a useful range of approximately 8 kilometres (5.0 mi). They produced units commercially for the <a href="/wiki/German_Navy" title="German Navy">German Navy</a>, which were further adapted to increase their range to 11 kilometres (6.8 mi) using voice-modulated ship <a href="/wiki/Searchlight" title="Searchlight">searchlights</a>.<sup id="cite_ref-Groth_5-5" class="reference"><a href="#cite_note-Groth-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p><p><a href="/wiki/British_Admiralty" class="mw-redirect" title="British Admiralty">British Admiralty</a> research during WWI resulted in the development of a vibrating mirror modulator in 1916. More sensitive <a href="/wiki/Molybdenite" title="Molybdenite">molybdenite</a> receiver cells, which also had greater sensitivity to infra-red radiation, replaced the older selenium cells in 1917.<sup id="cite_ref-Groth_5-6" class="reference"><a href="#cite_note-Groth-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> The United States and German governments also worked on technical improvements to Bell's system.<sup id="cite_ref-32" class="reference"><a href="#cite_note-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> </p><p>By 1935 the German <a href="/wiki/Carl_Zeiss_AG" title="Carl Zeiss AG">Carl Zeiss Company</a> had started producing infra-red photophones for the <a href="/wiki/German_Army_(Wehrmacht)" class="mw-redirect" title="German Army (Wehrmacht)">German Army</a>'s tank battalions, employing tungsten lamps with infra-red filters which were modulated by vibrating mirrors or prisms. These also used receivers which employed <a href="/wiki/Lead_sulfide" title="Lead sulfide">lead sulfide</a> detector cells and amplifiers, boosting their range to 14 kilometres (8.7 mi) under optimal conditions. The Japanese and Italian armies also attempted similar development of lightwave telecommunications before 1945.<sup id="cite_ref-Groth_5-7" class="reference"><a href="#cite_note-Groth-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p><p>Several military laboratories, including those in the United States, continued R&D efforts on the photophone into the 1950s, experimenting with high-pressure vapour and mercury arc lamps of between 500 and 2,000 watts power.<sup id="cite_ref-Groth_5-8" class="reference"><a href="#cite_note-Groth-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Commemorations">Commemorations</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photophone&action=edit&section=5" title="Edit section: Commemorations"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1224211176">.mw-parser-output .quotebox{background-color:#F9F9F9;border:1px solid #aaa;box-sizing:border-box;padding:10px;font-size:88%;max-width:100%}.mw-parser-output .quotebox.floatleft{margin:.5em 1.4em .8em 0}.mw-parser-output .quotebox.floatright{margin:.5em 0 .8em 1.4em}.mw-parser-output .quotebox.centered{overflow:hidden;position:relative;margin:.5em auto .8em auto}.mw-parser-output .quotebox.floatleft span,.mw-parser-output .quotebox.floatright span{font-style:inherit}.mw-parser-output .quotebox>blockquote{margin:0;padding:0;border-left:0;font-family:inherit;font-size:inherit}.mw-parser-output .quotebox-title{text-align:center;font-size:110%;font-weight:bold}.mw-parser-output .quotebox-quote>:first-child{margin-top:0}.mw-parser-output .quotebox-quote:last-child>:last-child{margin-bottom:0}.mw-parser-output .quotebox-quote.quoted:before{font-family:"Times New Roman",serif;font-weight:bold;font-size:large;color:gray;content:" “ ";vertical-align:-45%;line-height:0}.mw-parser-output .quotebox-quote.quoted:after{font-family:"Times New Roman",serif;font-weight:bold;font-size:large;color:gray;content:" ” ";line-height:0}.mw-parser-output .quotebox .left-aligned{text-align:left}.mw-parser-output .quotebox .right-aligned{text-align:right}.mw-parser-output .quotebox .center-aligned{text-align:center}.mw-parser-output .quotebox .quote-title,.mw-parser-output .quotebox .quotebox-quote{display:block}.mw-parser-output .quotebox cite{display:block;font-style:normal}@media screen and (max-width:640px){.mw-parser-output .quotebox{width:100%!important;margin:0 0 .8em!important;float:none!important}}</style><div class="quotebox pullquote floatright" style=";"> <blockquote class="quotebox-quote center-aligned" style=""> <div class="poem"> <p>FROM THE TOP FLOOR OF THIS BUILDING<br /> WAS SENT ON JUNE 3, 1880<br /> OVER A BEAM OF LIGHT TO 1325 'L' STREET<br /> THE FIRST WIRELESS TELEPHONE MESSAGE<br /> IN THE HISTORY OF THE WORLD.<br /> THE APPARATUS USED IN SENDING THE MESSAGE<br /> WAS THE PHOTOPHONE INVENTED BY<br /> ALEXANDER GRAHAM BELL<br /> INVENTOR OF THE TELEPHONE<br /> THIS PLAQUE WAS PLACED HERE BY<br /> ALEXANDER GRAHAM BELL CHAPTER<br /> TELEPHONE PIONEERS OF AMERICA<br /> MARCH 3, 1947<br /> THE CENTENNIAL OF DR. BELL'S BIRTH </p> </div> </blockquote> <div style="padding-bottom: 0;"><cite class="center-aligned" style="">Marker on the Franklin School commemorating the first formal trial</cite></div> </div> <p>On March 3, 1947, the centenary of <a href="/wiki/Alexander_Graham_Bell" title="Alexander Graham Bell">Alexander Graham Bell</a>'s birth, the <a href="/wiki/Pioneers,_a_Volunteer_Network" title="Pioneers, a Volunteer Network">Telephone Pioneers of America</a> dedicated a historical marker on the side of one of the buildings, the <a href="/wiki/Franklin_School_(Washington,_D.C.)" title="Franklin School (Washington, D.C.)">Franklin School</a>, which Bell and <a href="/wiki/Charles_Sumner_Tainter" title="Charles Sumner Tainter">Sumner Tainter</a> used for their first formal trial involving a considerable distance. Tainter had originally stood on the roof of the school building and transmitted to Bell at the window of his laboratory. The marker did not acknowledge Tainter's scientific and engineering contributions.<sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:No_original_research" title="Wikipedia:No original research"><span title="The material near this tag possibly contains original research. (September 2017)">original research?</span></a></i>]</sup> </p><p>On February 19, 1980, exactly 100 years to the day after Bell and Tainter's first photophone transmission in their laboratory, staff from the <a href="/wiki/Smithsonian_Institution" title="Smithsonian Institution">Smithsonian Institution</a>, the <a href="/wiki/National_Geographic_Society" title="National Geographic Society">National Geographic Society</a> and AT&T's <a href="/wiki/Bell_Labs" title="Bell Labs">Bell Labs</a> gathered at the location of Bell's former 1325 'L' Street <a href="/wiki/Volta_Laboratory_and_Bureau" title="Volta Laboratory and Bureau">Volta Laboratory</a> in Washington, D.C. for a commemoration of the event.<sup id="cite_ref-Gallardo+Mims_11-1" class="reference"><a href="#cite_note-Gallardo+Mims-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-NS-1986.02.27_33-0" class="reference"><a href="#cite_note-NS-1986.02.27-33"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> </p><p>The Photophone Centenary commemoration had first been proposed by electronics researcher and writer <a href="/wiki/Forrest_Mims" title="Forrest Mims">Forrest M. Mims</a>, who suggested it to Dr. <a href="/wiki/Melville_Bell_Grosvenor" title="Melville Bell Grosvenor">Melville Bell Grosvenor</a>, the inventor's grandson, during a visit to his office at the National Geographic Society. The historic grouping later observed the centennial of the photophone's first successful laboratory transmission by using Mims hand-made demonstration photophone, which functioned similar to Bell and Tainter's model.<sup id="cite_ref-Mims_1982,_p._12_20-1" class="reference"><a href="#cite_note-Mims_1982,_p._12-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-34" class="reference"><a href="#cite_note-34"><span class="cite-bracket">[</span>Note 1<span class="cite-bracket">]</span></a></sup> </p><p>Mims also built and provided a pair of modern hand-held battery-powered <a href="/wiki/Fiber-optic_communication#Transmitters" title="Fiber-optic communication">LED transceivers</a> connected by 100 yards (91 m) of <a href="/wiki/Optical_fiber" title="Optical fiber">optical fiber</a>. The Bell Labs' Richard Gundlach and the Smithsonian's Elliot Sivowitch used the device at the commemoration to demonstrate one of the photophone's modern-day descendants. The National Geographic Society also mounted a special educational exhibit in its Explorer's Hall, highlighting the photophone's invention with original items borrowed from the Smithsonian Institution.<sup id="cite_ref-35" class="reference"><a href="#cite_note-35"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photophone&action=edit&section=6" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1184024115">.mw-parser-output .div-col{margin-top:0.3em;column-width:30em}.mw-parser-output .div-col-small{font-size:90%}.mw-parser-output .div-col-rules{column-rule:1px solid #aaa}.mw-parser-output .div-col dl,.mw-parser-output .div-col ol,.mw-parser-output .div-col ul{margin-top:0}.mw-parser-output .div-col li,.mw-parser-output .div-col dd{page-break-inside:avoid;break-inside:avoid-column}</style><div class="div-col" style="column-width: 30em;"> <ul><li><a href="/wiki/Atomic_line_filter" title="Atomic line filter">Atomic line filter</a></li> <li><a href="/wiki/Free-space_optical_communication" title="Free-space optical communication">Free-space optical communication</a></li> <li><a href="/wiki/History_of_telecommunication" title="History of telecommunication">History of telecommunication</a></li> <li><a href="/wiki/Laser_microphone" title="Laser microphone">Laser microphone</a></li> <li><a href="/wiki/Mie_scattering" title="Mie scattering">Mie scattering</a></li> <li><a href="/wiki/Modulating_retro-reflector" title="Modulating retro-reflector">Modulating retro-reflector</a></li> <li><a href="/wiki/Optical_sound" title="Optical sound">Optical sound</a></li> <li><a href="/wiki/Optical_window" title="Optical window">Optical window</a></li> <li><a href="/wiki/Photoacoustic_effect" title="Photoacoustic effect">Photoacoustic effect</a></li> <li><a href="/wiki/Radio_window" title="Radio window">Radio window</a></li> <li><a href="/wiki/Rayleigh_scattering" title="Rayleigh scattering">Rayleigh scattering</a></li> <li><a href="/wiki/Semaphore_line" class="mw-redirect" title="Semaphore line">Semaphore line</a></li> <li><a href="/wiki/Visible_light_communication" title="Visible light communication">Visible light communication</a></li> <li><a href="/wiki/Volta_Laboratory_and_Bureau" title="Volta Laboratory and Bureau">Volta Laboratory and Bureau</a></li></ul> </div> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photophone&action=edit&section=7" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><b> Footnotes </b> </p> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-34"><span class="mw-cite-backlink"><b><a href="#cite_ref-34">^</a></b></span> <span class="reference-text"> The demonstration model was a replica in principle but not identical to Bell and Tainter's model. The commemorative model transmitter was a thin mirror cemented to a short aluminum speaking tube, and its receiver was a silicon solar cell and audio amplifier, both installed in a lantern light housing.</span> </li> </ol></div></div> <p><b> Citations </b> </p> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239543626"><div class="reflist reflist-columns references-column-width" style="column-width: 30em;"> <ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text">Bruce 1990, pg. 336</span> </li> <li id="cite_note-SDU-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-SDU_2-0">^</a></b></span> <span class="reference-text">Jones, Newell. <a rel="nofollow" class="external text" href="http://history.sandiego.edu/gen/recording/ar304.html">First 'Radio' Built by San Diego Resident Partner of Inventor of Telephone: Keeps Notebook of Experiences With Bell</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20020219111153/http://history.sandiego.edu/gen/recording/ar304.html">Archived</a> 2002-02-19 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a>, San Diego Evening Tribune, July 31, 1937. Retrieved from the University of San Diego History Department website, November 26, 2009.</span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text">Bruce 1990, pg. 338</span> </li> <li id="cite_note-Carson_2007,_pg._76–78-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-Carson_2007,_pg._76–78_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Carson_2007,_pg._76–78_4-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Carson 2007, pg. 76–78</span> </li> <li id="cite_note-Groth-5"><span class="mw-cite-backlink">^ <a href="#cite_ref-Groth_5-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Groth_5-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Groth_5-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Groth_5-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-Groth_5-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-Groth_5-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-Groth_5-6"><sup><i><b>g</b></i></sup></a> <a href="#cite_ref-Groth_5-7"><sup><i><b>h</b></i></sup></a> <a href="#cite_ref-Groth_5-8"><sup><i><b>i</b></i></sup></a></span> <span class="reference-text">Groth, Mike. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20211022155909/http:/www.bluehaze.com.au/modlight/GrothArticle1.htm">Photophones Revisted</a>, 'Amateur Radio' magazine, <a href="/wiki/Wireless_Institute_of_Australia" title="Wireless Institute of Australia">Wireless Institute of Australia</a>, Melbourne, April 1987 pp. 12–17 and May 1987 pp. 13–17.</span> </li> <li id="cite_note-Mims_1982,_p._11-6"><span class="mw-cite-backlink">^ <a href="#cite_ref-Mims_1982,_p._11_6-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Mims_1982,_p._11_6-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Mims 1982, p. 11.</span> </li> <li id="cite_note-Phillipson+Neilson-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-Phillipson+Neilson_7-0">^</a></b></span> <span class="reference-text">Phillipson, Donald J.C., and Neilson, Laura <a rel="nofollow" class="external text" href="https://www.thecanadianencyclopedia.ca/en/article/alexander-graham-bell-aviation-pioneer">Bell, Alexander Graham</a>, The Canadian Encyclopedia online. Retrieved 2009-08-06</span> </li> <li id="cite_note-Mims_1982,_p._14-8"><span class="mw-cite-backlink">^ <a href="#cite_ref-Mims_1982,_p._14_8-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Mims_1982,_p._14_8-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Mims 1982, p. 14.</span> </li> <li id="cite_note-Morgan-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-Morgan_9-0">^</a></b></span> <span class="reference-text">Morgan, Tim J. "The Fiber Optic Backbone", <a href="/wiki/University_of_North_Texas" title="University of North Texas">University of North Texas</a>, 2011.</span> </li> <li id="cite_note-AmericanScientist-1984.V72.No1-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-AmericanScientist-1984.V72.No1_10-0">^</a></b></span> <span class="reference-text">Miller, Stewart E. "Lightwaves and Telecommunication", <i><a href="/wiki/American_Scientist" title="American Scientist">American Scientist</a></i>, Sigma Xi, The Scientific Research Society, January–February 1984, Vol. 72, No. 1, pp. 66–71, <a rel="nofollow" class="external text" href="https://www.jstor.org/stable/i27852430">Issue Stable URL</a>.</span> </li> <li id="cite_note-Gallardo+Mims-11"><span class="mw-cite-backlink">^ <a href="#cite_ref-Gallardo+Mims_11-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Gallardo+Mims_11-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Gallardo, Arturo; <a href="/wiki/Forrest_Mims" title="Forrest Mims">Mims III, Forrest M.</a> <a rel="nofollow" class="external text" href="http://www.mysanantonio.com/default/article/Fiber-optic-communication-began-130-years-ago-783469.php">Fiber-optic Communication Began 130 Years Ago</a>, <i><a href="/wiki/San_Antonio_Express-News" title="San Antonio Express-News">San Antonio Express-News</a></i>, June 21, 2010. Accessed January 1, 2013.</span> </li> <li id="cite_note-Clark-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-Clark_12-0">^</a></b></span> <span class="reference-text">Clark, J. <a rel="nofollow" class="external text" href="https://ieeexplore.ieee.org/Xplore/home.jsp;jsessionid=6C6A7AE68101019670FA3A03F201C9FE">An Introduction to Communications with Optical Carriers</a>, IEEE Students' Quarterly Journal, June 1966, Vol.36, Iss.144, pp. 218–222, <style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://www.worldcat.org/search?fq=x0:jrnl&q=n2:0039-2871">0039-2871</a>, <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1049%2Fsqj.1966.0040">10.1049/sqj.1966.0040</a>. Retrieved from IEEExplore website August 19, 2011.</span> </li> <li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBell1881" class="citation journal cs1">Bell, Alexander Graham (28 May 1881). <a rel="nofollow" class="external text" href="http://www.jstor.org/stable/2900190">"The Production of Sound by Radiant Energy"</a>. <i>Science</i>. <b>2</b> (48): 242–253. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1126%2Fscience.os-2.49.242">10.1126/science.os-2.49.242</a>. <a href="/wiki/JSTOR_(identifier)" class="mw-redirect" title="JSTOR (identifier)">JSTOR</a> <a rel="nofollow" class="external text" href="https://www.jstor.org/stable/2900190">2900190</a>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/17741736">17741736</a><span class="reference-accessdate">. Retrieved <span class="nowrap">11 Oct</span> 2022</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Science&rft.atitle=The+Production+of+Sound+by+Radiant+Energy&rft.volume=2&rft.issue=48&rft.pages=242-253&rft.date=1881-05-28&rft_id=info%3Apmid%2F17741736&rft_id=https%3A%2F%2Fwww.jstor.org%2Fstable%2F2900190%23id-name%3DJSTOR&rft_id=info%3Adoi%2F10.1126%2Fscience.os-2.49.242&rft.aulast=Bell&rft.aufirst=Alexander+Graham&rft_id=http%3A%2F%2Fwww.jstor.org%2Fstable%2F2900190&rfr_id=info%3Asid%2Fen.wikipedia.org%3APhotophone" class="Z3988"></span></span> </li> <li id="cite_note-Bell-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-Bell_14-0">^</a></b></span> <span class="reference-text"><a href="/wiki/Alexander_Graham_Bell" title="Alexander Graham Bell">Bell, Alexander Graham</a>. "On the Production and Reproduction of Speech by Light", <i><a href="/wiki/American_Journal_of_Science" title="American Journal of Science">American Journal of Science</a></i>, October 1880, Vol. 20, No. 118, pp. 305–324.</span> </li> <li id="cite_note-Grosvenor_&_Wesson-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-Grosvenor_&_Wesson_15-0">^</a></b></span> <span class="reference-text">Grosvenor and Wesson 1997, p. 104.</span> </li> <li id="cite_note-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-16">^</a></b></span> <span class="reference-text">Ernest Victor Heyn, Fire of genius: inventors of the past century: based on the files of Popular Science Monthly since its founding in 1872, Anchor Press/Doubleday – 1976, page 74</span> </li> <li id="cite_note-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-17">^</a></b></span> <span class="reference-text">Mims 1982, pp. 6–7.</span> </li> <li id="cite_note-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-18">^</a></b></span> <span class="reference-text">Mims 1982, p. 7.</span> </li> <li id="cite_note-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-19">^</a></b></span> <span class="reference-text">Mims 1982, p. 10.</span> </li> <li id="cite_note-Mims_1982,_p._12-20"><span class="mw-cite-backlink">^ <a href="#cite_ref-Mims_1982,_p._12_20-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Mims_1982,_p._12_20-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Mims 1982, p. 12.</span> </li> <li id="cite_note-NYT-18800830-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-NYT-18800830_21-0">^</a></b></span> <span class="reference-text">Editorial, <i><a href="/wiki/The_New_York_Times" title="The New York Times">The New York Times</a></i>, August 30, 1880</span> </li> <li id="cite_note-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-22">^</a></b></span> <span class="reference-text">International Fiber Optics & Communication, June 1986, p. 29</span> </li> <li id="cite_note-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-23">^</a></b></span> <span class="reference-text">Carson 2007, pg.77</span> </li> <li id="cite_note-Bruce_1990,_pg.337-24"><span class="mw-cite-backlink">^ <a href="#cite_ref-Bruce_1990,_pg.337_24-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Bruce_1990,_pg.337_24-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Bruce 1990, pg. 337</span> </li> <li id="cite_note-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-25">^</a></b></span> <span class="reference-text">Bruce 1990, pg. 339</span> </li> <li id="cite_note-NS-1984.01.12-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-NS-1984.01.12_26-0">^</a></b></span> <span class="reference-text">Hecht, Jeff. <a rel="nofollow" class="external text" href="https://books.google.com/books?id=CHvVTAcy-tkC&pg=PA12">Fiber Optics Calls Up The Past</a>, <i><a href="/wiki/New_Scientist" title="New Scientist">New Scientist</a></i>, January 12, 1984, pp. 12–13.</span> </li> <li id="cite_note-27"><span class="mw-cite-backlink"><b><a href="#cite_ref-27">^</a></b></span> <span class="reference-text">Carson 2007, pp. 77–78</span> </li> <li id="cite_note-28"><span class="mw-cite-backlink"><b><a href="#cite_ref-28">^</a></b></span> <span class="reference-text">Carson 2007, pg.78</span> </li> <li id="cite_note-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-29">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://babel.hathitrust.org/cgi/pt?id=mdp.39015057148481;view=1up;seq=13">Cover page</a> <i>Technical World</i>, March 1905.</span> </li> <li id="cite_note-30"><span class="mw-cite-backlink"><b><a href="#cite_ref-30">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://babel.hathitrust.org/cgi/pt?id=nyp.33433090837562;view=1up;seq=133">"Correspondence: Wireless Telephony"</a> (October 30, 1902 letter from Ernst Ruhmer), <i>The Electrician</i>, November 7, 1902, page 111.</span> </li> <li id="cite_note-31"><span class="mw-cite-backlink"><b><a href="#cite_ref-31">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://babel.hathitrust.org/cgi/pt?id=uc1.$b33006;view=1up;seq=73"><i>Wireless Telephony In Theory and Practice</i></a> by Ernst Ruhmer, 1908, pages 55–59.</span> </li> <li id="cite_note-32"><span class="mw-cite-backlink"><b><a href="#cite_ref-32">^</a></b></span> <span class="reference-text">Mims 1982, pp. 14–17.</span> </li> <li id="cite_note-NS-1986.02.27-33"><span class="mw-cite-backlink"><b><a href="#cite_ref-NS-1986.02.27_33-0">^</a></b></span> <span class="reference-text">Hecht, Jeff. <a rel="nofollow" class="external text" href="https://books.google.com/books?id=Q9YLS_wzgfwC&pg=PA51">"Yarns From The Technological Jungle: Siliconnections: Coming Of Age In The Electronic Era"</a>, <i><a href="/wiki/New_Scientist" title="New Scientist">New Scientist</a></i>, February 27, 1986, pp. 50–51.</span> </li> <li id="cite_note-35"><span class="mw-cite-backlink"><b><a href="#cite_ref-35">^</a></b></span> <span class="reference-text">Mims 1982, pp. 6 & 12.</span> </li> </ol></div> <p><b> Bibliography </b> </p> <style data-mw-deduplicate="TemplateStyles:r1239549316">.mw-parser-output .refbegin{margin-bottom:0.5em}.mw-parser-output .refbegin-hanging-indents>ul{margin-left:0}.mw-parser-output .refbegin-hanging-indents>ul>li{margin-left:0;padding-left:3.2em;text-indent:-3.2em}.mw-parser-output .refbegin-hanging-indents ul,.mw-parser-output .refbegin-hanging-indents ul li{list-style:none}@media(max-width:720px){.mw-parser-output .refbegin-hanging-indents>ul>li{padding-left:1.6em;text-indent:-1.6em}}.mw-parser-output .refbegin-columns{margin-top:0.3em}.mw-parser-output .refbegin-columns ul{margin-top:0}.mw-parser-output .refbegin-columns li{page-break-inside:avoid;break-inside:avoid-column}@media screen{.mw-parser-output .refbegin{font-size:90%}}</style><div class="refbegin refbegin-columns references-column-width" style="column-width: 30em"> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCarson2007" class="citation book cs1">Carson, Mary Kay (2007). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=a46ivzJ1yboC">"chapter 8"</a>. <a rel="nofollow" class="external text" href="https://archive.org/details/alexandergrahamb0000cars/page/76"><i>Alexander Graham Bell: Giving Voice To The World</i></a>. Sterling Biographies. New York: Sterling Publishing Co., Inc. pp. <a rel="nofollow" class="external text" href="https://archive.org/details/alexandergrahamb0000cars/page/76">76–78</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-4027-3230-0" title="Special:BookSources/978-1-4027-3230-0"><bdi>978-1-4027-3230-0</bdi></a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/182527281">182527281</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=chapter+8&rft.btitle=Alexander+Graham+Bell%3A+Giving+Voice+To+The+World&rft.place=New+York&rft.series=Sterling+Biographies&rft.pages=76-78&rft.pub=Sterling+Publishing+Co.%2C+Inc.&rft.date=2007&rft_id=info%3Aoclcnum%2F182527281&rft.isbn=978-1-4027-3230-0&rft.aulast=Carson&rft.aufirst=Mary+Kay&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3Da46ivzJ1yboC&rfr_id=info%3Asid%2Fen.wikipedia.org%3APhotophone" class="Z3988"></span></li> <li><a href="/wiki/Alexander_Graham_Bell" title="Alexander Graham Bell">Bell, A. G</a>: "On the Production and Reproduction of Sound by Light", <i><a href="/wiki/American_Journal_of_Science" title="American Journal of Science">American Journal of Science</a></i>, Third Series, Vol. XX, #118, October 1880, pp. 305–324; also published as "Selenium and the Photophone" in <i><a href="/wiki/Nature_(journal)" title="Nature (journal)">Nature</a></i>, September 1880.</li> <li><a href="/wiki/List_of_Boston_University_people#Guggenheim_Fellows" title="List of Boston University people">Bruce, Robert V</a> <i>Bell: Alexander Bell and the Conquest of Solitude</i>, Ithaca, New York: <a href="/wiki/Cornell_University" title="Cornell University">Cornell University Press</a>, 1990. <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-8014-9691-8" title="Special:BookSources/0-8014-9691-8">0-8014-9691-8</a>.</li> <li><a href="/wiki/Forrest_Mims" title="Forrest Mims">Mims III, Forest M</a>. <a rel="nofollow" class="external text" href="https://books.google.com/books?id=zoaSp1BJu50C&pg=PA1">The First Century of Lightwave Communications</a>, <i>Fiber Optics Weekly Update</i>, Information Gatekeepers, February 10–26, 1982, pp. 6–23.</li> <li>Grosvenor, Edwin S. and Morgan Wesson. <i>Alexander Graham Bell: The Life and Times of the Man Who Invented the Telephone</i>. New York: Harry N. Abrahms, Inc., 1997. <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-8109-4005-1" title="Special:BookSources/0-8109-4005-1">0-8109-4005-1</a>.</li></ul> </div> <div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photophone&action=edit&section=8" title="Edit section: Further reading"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a rel="nofollow" class="external text" href="http://www.bluehaze.com.au/modlight/ModLightBiblio.htm">Chris Long and Mike Groth's optical audio telecommunications webpage</a></li> <li>Ackroyd, William. "The Photophone" in "Science for All", Vol. 2 (R. Brown, ed.), Cassell & Co., London, circa 1884, pp. 307–312. A popular account, profusely illustrated with steel engravings.</li> <li>Armengaud, J. " Le photophone de M.Graham Bell". Soc. Ing. civ. Mem., year 1880, Vol 2. pp. 513–522.</li> <li>AT&T Company. "The Radiophone", pamphlet distributed at Louisiana Purchase Exhibition, St Louis, Missouri, 1904. Describes the photophone work of Hammond V Hayes at the Bell Labs (patented 1897) and the German engineer H T Simon in the same year.</li> <li><a href="/wiki/Alexander_Graham_Bell" title="Alexander Graham Bell">Bell, Alexander Graham</a>. "On the Production and Reproduction of Sound by Light: the Photophone". Am. Ass. for the Advancement of Sci., Proc., Vol 29., October 1880, pp. 115–136. Also in <i>American Journal of Science</i>, Series 3. No. 20, 1880, pp. 305–324; Eng. L., 30. 1880, pp. 240–242; Electrician, Vol 5. 1880, pp. 214–215, 220–221, 237; <i>Journal of the Society of Telegraph Engineers</i>, No. 9, 1880, pp. 404–426; Nat. L., Vol 22. 1880, pp. 500–503; Ann. Chim. Phys., Serie 5. Vol 21. 1880, pp. 399–430; E.T.Z., Vol. 1. 1880, pp. 391–396. Discussed at length in Eng. L., Vol 30. 1880, pp. 253–254, 407–409. In these papers, Bell accords the credit for the first demonstrations of the transmission of speech by light to a Mr A C Brown of London "in September or October 1878".</li> <li><a href="/wiki/Alexander_Graham_Bell" title="Alexander Graham Bell">Bell, Alexander Graham</a>. "Sur l'application du photophone a l'etude des bruits qui ont lieu a la surface solaire". C. R., Vol. 91. 1880, pp. 726–727.</li> <li><a href="/wiki/Alexander_Graham_Bell" title="Alexander Graham Bell">Bell, Alexander Graham</a>. "Professor A G Bell on Selenium and the Photophone". Pharm. J. and Trans., Series 3. Vol. 11., 1880–1881, pp. 272–276; The Electrician No 5, 18 September 1880, pp 220–221 and 2 October 1880 pp 237; Nature (London) Vol 22, 23 September 1880, pp. 500–503; Engineering Vol 30, pp 240–242, 253, 254, 407–409; and Journal of the Society of Telegraph Engineers Vol 9, pp 375–387.</li> <li><a href="/wiki/Alexander_Graham_Bell" title="Alexander Graham Bell">Bell, Alexander Graham</a>. "Other papers on the photophone" E.T.Z. No. 1, 1880, pp 391–396; <i>Journal of the Society for the Arts</i> 1880, No. 28, pp 847–848 & No. 29 pp 60–62; C.R. No. 91, 1880–1881, pp 595–598, 726, 727, 929–931, 982, 1882 pp 409–412, 450, 451, 1224–1227.</li> <li><a href="/wiki/Alexander_Graham_Bell" title="Alexander Graham Bell">Bell, Alexander Graham</a>. "Le Photophone De La Production Et De La Lumiere". Gauthier-Villars, Imprimeur-Libraire, Paris. 1880. <small>(Note: this is item #26, Folder #4, as noted in "Finding Aid for the Alexander Graham Bell Collection, 1880–1925", Collection number: 308, <a href="/wiki/UCLA" class="mw-redirect" title="UCLA">UCLA</a> Library, Department of Special Collections Manuscripts Division, as viewable at the <a rel="nofollow" class="external text" href="http://oac.cdlib.org/findaid/ark:/13030/kt8c6008r5">Online Archive of California</a>)</small></li> <li>"Bell's Photophone". Nature Vol 24, 4 November 1880; The Electrician, Vol. 6, 1881, pp. 136–138.</li> <li>Appleton's Journal. "The Photophone". Appleton's Journal, Vol. 10 No. 56, New York, February 1881, pp. 181–182.</li> <li>Bidwell, Shelford. "The Photophone". Nature., 23. 1881, pp. 58–59.</li> <li>Bidwell, Shelford. "Selenium and Its Applications to the Photophone and Telephotography". Proceedings of the Royal Institution (G.B.), Vol 9. 1881, pp. 524–535; The English Mechanic and World Of Science, Vol. 33, 22 April 1881, pp. 158–159 and 29 April 1881 pp. 180–181. Also in Chem. News, Vol. 44, 1881, pp. 1–3, 18–21. (From a lecture at the Royal Institution on 11 March 1881).</li> <li>Breguet, A. "Les recepteurs photophoniques de selenium". Ann. Chim. Phys., Series 5. Vol 21. 1880, pp. 560–563.</li> <li>Breguet, A. "Sur les experiences photophonique du Professeur Alexander Graham Bell et de M. Sumner Tainter": C.R.; Vol 91., 1880, pp 595–598.</li> <li>Electrician. "Bell's Photophone", Electrician, Vol. 6, February 5, 1881, pp. 136–138,183.</li> <li>Jamieson, Andrew. Nat. L., Vol. 10, 1881, p. 11. This Glasgow scientist seems to have been the first to suggest the usage of a manometric gas flame for optical transmission, demonstrated at a meeting of the Glasgow Philosophical Society; "The History of selenium and its action in the Bell Photophone, with description of recently designed form", Proceedings of the Philosophical Society of Glasgow No. 13, 1881, ***Moser, J. "The Microphonic Action of Selenium Cells". Phys. Soc., Proc., Vol. 4, 1881, pp. 348–360. Also in Phil. Mag., Series 5, Vol.12, 1881, pp. 212–223.</li> <li>Kalischer, S. "Photophon Ohne Batterie". Rep. f. Phys., Vol. 17., 1881, pp. 563–570.</li> <li><a href="/wiki/Catherine_MacKenzie" title="Catherine MacKenzie">MacKenzie, Catherine</a> "Alexander Graham Bell", Houghton Mifflin Company, Boston, p. 226, 1928.</li> <li>Mercadier, E. "La radiophonie indirecte". Lumiere Electrique, Vol. 4, 1881, pp. 295–299.</li> <li>Mercadier, E. "Sur la radiophonie produite a l'aide du selenium". C. R., Vol. 92,1881, pp. 705–707.</li> <li>Mercadier, E. "Sur la construction de recepteurs photophoniques a selenium". C. R., Vol. 92, 1881, pp. 789–790.</li> <li>Mercadier, E. "Sur l'influence de la temperature sur les recepteurs radiophoniques a selenium". C. R., Vol. 92, 1881, pp. 1407–1408.</li> <li>Molera & Cebrian. "The Photophone". Eng. L., Vol. 31, 1881, p. 358.</li> <li>Preece, Sir William H. "Radiophony", Engineering Vol. 32, 8 July 1881, pp. 29–33; <i>Journal of the Society of Telegraph Engineers</i>, Vol 10, 1881, pp. 212–228. On the photophone.</li> <li>Rankine, A.O. "Talking over a Sunbeam". El. Exp. (N. Y.), Vol. 7, 1920, pp. 1265–1316.</li> <li>Sternberg, J.M. <a rel="nofollow" class="external text" href="http://memory.loc.gov/cgi-bin/query/P?magbell:1:./temp/~ammem_3ShO::@@@mdb=mcc,gottscho,detr,nfor,wpa,aap,cwar,bbpix,cowellbib,calbkbib,consrvbib,bdsbib,dag,fsaall,gmd,pan,vv,presp,varstg,suffrg,nawbib,horyd,wtc,toddbib,mgw,ncr,ngp,musdibib,hlaw,papr,lhbumbib,rbpebib,lbcoll,alad,hh,aaodyssey,magbell,bbc,dcm,raelbib,runyon,dukesm,lomaxbib,mtj,gottlieb,aep,qlt,coolbib,fpnas,aasm,denn,relpet,amss,aaeo,mff,afc911bib,mjm,mnwp,rbcmillerbib,molden,ww2map,mfdipbib,afcnyebib,klpmap,hawp,omhbib,rbaapcbib,mal,ncpsbib,ncpm,lhbprbib,ftvbib,afcreed,aipn,cwband,flwpabib,wpapos,cmns,psbib,pin,coplandbib,cola,tccc,curt,mharendt,lhbcbbib,eaa,haybib,mesnbib,fine,cwnyhs,svybib,mmorse,afcwwgbib,mymhiwebib,uncall,afcwip,mtaft,manz,llstbib,fawbib,berl,fmuever,cdn,upboverbib,mussm,cic,afcpearl,awh,awhbib,sgp,wright,lhbtnbib,afcesnbib,hurstonbib,mreynoldsbib,spaldingbib,sgproto,scsmbib,afccalbib,mamcol">The Volta Prize of the French Academy Awarded to Prof. Alexander Graham Bell: A Talk With Dr. J.M. Sternberg</a>, The Evening Traveler, September 1, 1880, The Alexander Graham Bell Papers at the <a href="/wiki/Library_of_Congress" title="Library of Congress">Library of Congress</a></li> <li>Thompson, Silvanus P. "Notes on the Construction of the Photophone". Phys. Soc.Proc., Vol. 4, 1881, pp. 184–190. Also in Phil. Mag., Vol. 11, 1881, pp. 286–291. Abstracted in Chem. News, Vol. 43, 1881, p. 43; Eng. L., Vol. 31, 1881, p. 96.</li> <li>Tomlinson, H. "The Photophone". Nat. L., Vol. 23, 1881, pp. 457–458.</li> <li>U.S. Radio and Television Corp. "Ultra-violet rays used in Television", New York Times, 29 May 1929, p. 5: Demonstration of transmission of a low definition (mechanically scanned) video signal over a modulated light beam. Terminal stations 50 feet apart. Public demonstration at Bamberger and Company's Store, Newark, New Jersey. Earliest known usage of modulated light comms for conveying video signals. See also report "Invisible Ray Transmits Pictures" in Science and Invention, November 1929, Vol. 17, p. 629.</li> <li>White, R.H. "Photophone". Harmsworth's Wireless Encyclopaedia, Vol. 3, pp. 1541–1544.</li> <li>Weinhold, A. "Herstellung von Selenwiderstanden fur Photophonzwecke". E.T.Z., Vol. 1, 1880, p. 423.</li></ul> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photophone&action=edit&section=9" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1235681985">.mw-parser-output .side-box{margin:4px 0;box-sizing:border-box;border:1px solid #aaa;font-size:88%;line-height:1.25em;background-color:var(--background-color-interactive-subtle,#f8f9fa);display:flow-root}.mw-parser-output .side-box-abovebelow,.mw-parser-output .side-box-text{padding:0.25em 0.9em}.mw-parser-output .side-box-image{padding:2px 0 2px 0.9em;text-align:center}.mw-parser-output .side-box-imageright{padding:2px 0.9em 2px 0;text-align:center}@media(min-width:500px){.mw-parser-output .side-box-flex{display:flex;align-items:center}.mw-parser-output .side-box-text{flex:1;min-width:0}}@media(min-width:720px){.mw-parser-output .side-box{width:238px}.mw-parser-output .side-box-right{clear:right;float:right;margin-left:1em}.mw-parser-output .side-box-left{margin-right:1em}}</style><style data-mw-deduplicate="TemplateStyles:r1237033735">@media print{body.ns-0 .mw-parser-output .sistersitebox{display:none!important}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}</style><div class="side-box side-box-right plainlinks sistersitebox"><style data-mw-deduplicate="TemplateStyles:r1126788409">.mw-parser-output .plainlist ol,.mw-parser-output .plainlist ul{line-height:inherit;list-style:none;margin:0;padding:0}.mw-parser-output .plainlist ol li,.mw-parser-output .plainlist ul li{margin-bottom:0}</style> <div class="side-box-flex"> <div class="side-box-image"><span class="noviewer" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/40px-Wiktionary-logo-en-v2.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/60px-Wiktionary-logo-en-v2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/80px-Wiktionary-logo-en-v2.svg.png 2x" data-file-width="512" data-file-height="512" /></span></span></div> <div class="side-box-text plainlist">Look up <i><b><a href="https://en.wiktionary.org/wiki/Special:Search/photophone" class="extiw" title="wiktionary:Special:Search/photophone">photophone</a></b></i> in Wiktionary, the free dictionary.</div></div> </div> <ul><li><a rel="nofollow" class="external text" href="https://www.histv.net/bell-production-of-sound-by-light">Bell's speech</a> before the <a href="/wiki/American_Association_for_the_Advancement_of_Science" title="American Association for the Advancement of Science">American Association for the Advancement of Science</a> in <a href="/wiki/Boston" title="Boston">Boston</a> on August 27, 1880, in which he presented his paper<i> "On the Production and Reproduction of Sound by Light: the Photophone"</i>.</li> <li><a rel="nofollow" class="external text" href="http://www.modulatedlight.org/Modulated_Light_DX/ModLightBiblio.html">Long-distance Atmospheric Optical Communications, by Chris Long and Mike Groth (VK7MJ)</a></li> <li><a rel="nofollow" class="external text" href="https://www.histv.net/graham-bell-contribution-indirecte">Téléphone et photophone: les contributions indirectes de Graham Bell à l'idée de la vision à distance par l'électricité (1880–1895</a> <span class="languageicon">(in French)</span></li></ul> <div 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abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Alexander_Graham_Bell" title="Template:Alexander Graham Bell"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Alexander_Graham_Bell" title="Template talk:Alexander Graham Bell"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Alexander_Graham_Bell" title="Special:EditPage/Template:Alexander Graham Bell"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Alexander_Graham_Bell" style="font-size:114%;margin:0 4em"><a href="/wiki/Alexander_Graham_Bell" title="Alexander Graham Bell">Alexander Graham Bell</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Life and<br />family</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Alexander_Melville_Bell" title="Alexander Melville Bell">Alexander Melville Bell</a></li> <li><a href="/wiki/Beinn_Bhreagh" title="Beinn Bhreagh">Beinn Bhreagh, Nova Scotia</a></li> <li><a href="/wiki/Bell_House_(Colonial_Beach,_Virginia)" title="Bell House (Colonial Beach, Virginia)">Bell House (Virginia)</a></li> <li><a href="/wiki/Bras_d%27Or_Lake" title="Bras d'Or Lake">Bras d'Or Lake</a></li> <li><a href="/wiki/Chichester_Bell" title="Chichester Bell">Chichester Bell</a></li> <li><a href="/wiki/David_Fairchild" title="David Fairchild">David Fairchild</a></li> <li><a href="/wiki/Graham_Fairchild" title="Graham Fairchild">Graham Fairchild</a></li> <li><a href="/wiki/Edwin_S._Grosvenor" title="Edwin S. Grosvenor">Edwin S. Grosvenor</a></li> <li><a href="/wiki/Gardiner_Greene_Hubbard" title="Gardiner Greene Hubbard">Gardiner Greene Hubbard</a></li> <li><a href="/wiki/Gilbert_Hovey_Grosvenor" title="Gilbert Hovey Grosvenor">Gilbert Hovey Grosvenor</a></li> <li><a href="/wiki/Gilbert_M._Grosvenor" title="Gilbert M. Grosvenor">Gilbert M. Grosvenor</a></li> <li><a href="/wiki/Hubbard_Bell_Grossman_Pillot_Memorial" title="Hubbard Bell Grossman Pillot Memorial">Hubbard Bell Grossman Pillot Memorial</a></li> <li><a href="/wiki/Kendall_Myers" title="Kendall Myers">Kendall Myers</a></li> <li><a href="/wiki/Mabel_Gardiner_Hubbard" title="Mabel Gardiner Hubbard">Mabel Gardiner Hubbard</a></li> <li><a href="/wiki/Mabel_H._Grosvenor" title="Mabel H. Grosvenor">Mabel H. Grosvenor</a></li> <li><a href="/wiki/Melville_Bell_Grosvenor" title="Melville Bell Grosvenor">Melville Bell Grosvenor</a></li> <li><a href="/wiki/Second_International_Congress_on_Education_of_the_Deaf" title="Second International Congress on Education of the Deaf">Second International Congress on Education of the Deaf</a></li> <li><a href="/wiki/The_Telephone_Cases" title="The Telephone Cases">Telephone Cases</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">People</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Anthony_Pollok" title="Anthony Pollok">Anthony Pollok</a></li> <li><a href="/wiki/Charles_Williams_Jr._House" title="Charles Williams Jr. House">Charles Williams Jr.</a></li> <li><a href="/wiki/Glenn_Curtiss" title="Glenn Curtiss">Glenn Curtiss</a></li> <li><a href="/wiki/Marcellus_Bailey" title="Marcellus Bailey">Marcellus Bailey</a></li> <li><a href="/wiki/Thomas_Cowherd" title="Thomas Cowherd">Thomas Cowherd</a></li> <li><a href="/wiki/Thomas_Selfridge" title="Thomas Selfridge">Thomas Selfridge</a></li> <li><a href="/wiki/Thomas_A._Watson" title="Thomas A. Watson">Thomas A. Watson</a></li> <li><a href="/wiki/Walter_Seymour_Allward" title="Walter Seymour Allward">Walter Seymour Allward</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Works</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/AEA_Cygnet" title="AEA Cygnet">AEA Cygnet</a></li> <li><a href="/wiki/AEA_June_Bug" title="AEA June Bug">AEA June Bug</a></li> <li><a href="/wiki/AEA_Red_Wing" title="AEA Red Wing">AEA Red Wing</a></li> <li><a href="/wiki/AEA_Silver_Dart" title="AEA Silver Dart">AEA Silver Dart</a></li> <li><a href="/wiki/AEA_White_Wing" title="AEA White Wing">AEA White Wing</a></li> <li><a href="/wiki/Aerial_Experiment_Association" title="Aerial Experiment Association">Aerial Experiment Association</a></li> <li><a href="/wiki/Alexander_Graham_Bell_Association_for_the_Deaf_and_Hard_of_Hearing" title="Alexander Graham Bell Association for the Deaf and Hard of Hearing">Alexander Graham Bell Association for the Deaf and Hard of Hearing</a></li> <li><a href="/wiki/Bell_Boatyard" title="Bell Boatyard">Bell Boatyard</a></li> <li><a href="/wiki/Bell_Oionus_I" title="Bell Oionus I">Bell Oionus I</a></li> <li><a href="/wiki/Bell_System" title="Bell System">Bell System</a></li> <li><a href="/wiki/Bell_Telephone_Company" title="Bell Telephone Company">Bell Telephone Company</a></li> <li><a href="/wiki/Canadian_Aerodrome_Baddeck_No._1_and_No._2" title="Canadian Aerodrome Baddeck No. 1 and No. 2">Canadian Aerodrome Baddeck No. 1 and No. 2</a></li> <li><a href="/wiki/Canadian_Aerodrome_Company" title="Canadian Aerodrome Company">Canadian Aerodrome Company</a></li> <li><a href="/wiki/Clarke_Schools_for_Hearing_and_Speech" title="Clarke Schools for Hearing and Speech">Clarke Schools for Hearing and Speech</a></li> <li><a href="/wiki/Dictation_machine" title="Dictation machine">Dictation machine</a></li> <li><a href="/wiki/Edison_Gower-Bell_Telephone_Company_of_Europe" title="Edison Gower-Bell Telephone Company of Europe">Edison Gower-Bell Telephone Company of Europe</a></li> <li><a href="/wiki/Elisha_Gray_and_Alexander_Bell_telephone_controversy" title="Elisha Gray and Alexander Bell telephone controversy">Elisha Gray and Alexander Bell telephone controversy</a></li> <li><a href="/wiki/Graphophone" title="Graphophone">Graphophone</a></li> <li><a href="/wiki/HD-4" title="HD-4">HD-4</a></li> <li><a href="/wiki/Hubbard_Monoplane" title="Hubbard Monoplane">Hubbard Monoplane</a></li> <li><a href="/wiki/Life_Extension_Institute" title="Life Extension Institute">Life Extension Institute</a></li> <li><a href="/wiki/National_Geographic_Society" title="National Geographic Society">National Geographic Society</a></li> <li><a href="/wiki/National_Telephone_Company" title="National Telephone Company">National Telephone Company</a></li> <li><a href="/wiki/New_England_Telephone_and_Telegraph_Company" title="New England Telephone and Telegraph Company">New England Telephone and Telegraph Company</a></li> <li><a href="/wiki/Oriental_Telephone_Company" title="Oriental Telephone Company">Oriental Telephone Company</a></li> <li><a href="/wiki/Phonograph_cylinder" title="Phonograph cylinder">Phonograph cylinder</a></li> <li><a class="mw-selflink selflink">Photophone</a></li> <li><a href="/wiki/Volta_Laboratory_and_Bureau" title="Volta Laboratory and Bureau">Volta Laboratory and Bureau</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Tributes</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Alexander_Graham_Bell_National_Historic_Site" title="Alexander Graham Bell National Historic Site">Alexander Graham Bell National Historic Site</a></li> <li><a href="/wiki/Alexander_Graham_Bell_School_(Chicago)" title="Alexander Graham Bell School (Chicago)">Alexander Graham Bell School (Illinois)</a></li> <li><a href="/wiki/Alexander_Graham_Bell_honors_and_tributes" title="Alexander Graham Bell honors and tributes">Alexander Graham Bell honors and tributes</a></li> <li><a href="/wiki/Bell_Homestead_National_Historic_Site" title="Bell Homestead National Historic Site">Bell Homestead National Historic Site</a></li> <li><a href="/wiki/Bell_Memorial" title="Bell Memorial">Bell Telephone Memorial</a></li> <li><a href="/wiki/Graham_Bell_Island" title="Graham Bell Island">Graham Bell Island</a></li> <li><a href="/wiki/HMCS_Bras_d%27Or_(FHE_400)" title="HMCS Bras d'Or (FHE 400)">HMCS <i>Bras d'Or</i></a></li> <li><a href="/wiki/IEEE_Alexander_Graham_Bell_Medal" title="IEEE Alexander Graham Bell Medal">IEEE Alexander Graham Bell Medal</a></li> <li><a href="/wiki/Pioneers,_a_Volunteer_Network" title="Pioneers, a Volunteer Network">Pioneers, a Volunteer Network</a></li> <li><i><a href="/wiki/The_Story_of_Alexander_Graham_Bell" title="The Story of Alexander Graham Bell">The Story of Alexander Graham Bell</a></i> (1939 film)</li> <li><i><a href="/wiki/The_Sound_and_the_Silence" title="The Sound and the Silence">The Sound and the Silence</a></i> (1992 film)</li></ul> </div></td></tr><tr><td class="navbox-abovebelow hlist" colspan="2"><div> <ul><li><span class="noviewer" typeof="mw:File"><span title="Category"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/16px-Symbol_category_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/23px-Symbol_category_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/31px-Symbol_category_class.svg.png 2x" data-file-width="180" data-file-height="185" /></span></span> <a href="/wiki/Category:Alexander_Graham_Bell" title="Category:Alexander Graham Bell">Category</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Optical_telecommunication" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Optical_telecommunication" title="Template:Optical telecommunication"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Optical_telecommunication" title="Template talk:Optical telecommunication"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Optical_telecommunication" title="Special:EditPage/Template:Optical telecommunication"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Optical_telecommunication" style="font-size:114%;margin:0 4em"><a href="/wiki/Optical_communication" title="Optical communication">Optical telecommunication</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Basic</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Smoke_signal" title="Smoke signal">Smoke signal</a></li> <li><a href="/wiki/Beacon" title="Beacon">Beacon</a></li> <li><a href="/wiki/Hydraulic_telegraph" title="Hydraulic telegraph">Hydraulic telegraph</a></li> <li><a href="/wiki/International_maritime_signal_flags" title="International maritime signal flags">Ships' flags</a></li> <li><a href="/wiki/Optical_telegraph" title="Optical telegraph">Optical telegraph</a></li> <li><a href="/wiki/Heliograph" title="Heliograph">Heliograph</a></li> <li><a href="/wiki/Signal_lamp" title="Signal lamp">Signal lamp</a></li> <li><a class="mw-selflink selflink">Photophone</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Advanced</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Fiber-optic_communication" title="Fiber-optic communication">Fiber-optics</a> <ul><li><a href="/wiki/Optical_fiber" title="Optical fiber">Optical fiber</a> <ul><li><a href="/wiki/Fiber-optic_cable" title="Fiber-optic cable">Cable</a></li> <li><a href="/wiki/Optical_fiber_connector" title="Optical fiber connector">Connectors</a></li></ul></li></ul></li> <li><a href="/wiki/Optical_wireless_communications" title="Optical wireless communications">Optical wireless</a> <ul><li><a href="/wiki/Free-space_optical_communication" title="Free-space optical communication">Free-space</a></li> <li><a href="/wiki/Visible_light_communication" title="Visible light communication">Visible light</a></li> <li><a href="/wiki/Li-Fi" title="Li-Fi">Li-Fi</a></li> <li><a href="/wiki/Laser_communication_in_space" title="Laser communication in space">In space</a></li> <li><a href="/wiki/Consumer_IR" title="Consumer IR">Consumer IR</a></li></ul></li> <li><a href="/wiki/Optical_Transport_Network" class="mw-redirect" title="Optical Transport Network">Optical Transport Network</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Technologies</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Optical_Carrier_transmission_rates" title="Optical Carrier transmission rates">OC Rates</a></li> <li><a href="/wiki/Intensity_modulation" title="Intensity modulation">Intensity modulation</a></li> <li><a href="/wiki/Modulating_retro-reflector" title="Modulating retro-reflector">Modulating retro-reflector</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2" style="font-weight:bold;"><div> <ul><li><span class="noviewer" typeof="mw:File"><span title="Category"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/16px-Symbol_category_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/23px-Symbol_category_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/31px-Symbol_category_class.svg.png 2x" data-file-width="180" data-file-height="185" /></span></span> <a href="/wiki/Category:Optical_communications" title="Category:Optical communications">Category</a></li> <li><span class="noviewer" typeof="mw:File"><a href="/wiki/File:Symbol_portal_class.svg" class="mw-file-description" title="Portal"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/e/e2/Symbol_portal_class.svg/16px-Symbol_portal_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/e/e2/Symbol_portal_class.svg/23px-Symbol_portal_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/e/e2/Symbol_portal_class.svg/31px-Symbol_portal_class.svg.png 2x" data-file-width="180" data-file-height="185" /></a></span> <a href="/wiki/Portal:Telecommunication" title="Portal:Telecommunication">Portal</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Telephony" style="padding:3px"><table class="nowraplinks mw-collapsible uncollapsed navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Telephony" title="Template:Telephony"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Telephony" title="Template talk:Telephony"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Telephony" title="Special:EditPage/Template:Telephony"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Telephony" style="font-size:114%;margin:0 4em"><a href="/wiki/Telephony" title="Telephony">Telephony</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Types</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Landline" title="Landline">Landline</a></li> <li><a href="/wiki/Cable_telephony" title="Cable telephony">Cable telephony</a></li> <li><a href="/wiki/Mobile_phone" title="Mobile phone">Mobile phone</a></li> <li><a href="/wiki/Satellite_phone" title="Satellite phone">Satellite phone</a></li> <li><a class="mw-selflink selflink">Photophone</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Accessories</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Answering_machine" title="Answering machine">Answering machine</a></li> <li><a href="/wiki/Caller_ID" title="Caller ID">Caller ID</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Connectivity</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Cable_protection_system" title="Cable protection system">Cable protection system</a></li> <li><a href="/wiki/Communications_satellite" title="Communications satellite">Communications satellites</a></li> <li><a href="/wiki/Fiber-optic_communication" title="Fiber-optic communication">Fibre-optical</a></li> <li><a href="/wiki/Free-space_optical_communication" title="Free-space optical communication">Free-space optical</a></li> <li><a href="/wiki/Integrated_Services_Digital_Network" class="mw-redirect" title="Integrated Services Digital Network">ISDN</a></li> <li><a href="/wiki/Mobile_phone_signal" title="Mobile phone signal">Mobile phone signal</a></li> <li><a href="/wiki/Plain_old_telephone_service" title="Plain old telephone service">POTS</a></li> <li><a href="/wiki/Public_switched_telephone_network" title="Public switched telephone network">PSTN</a></li> <li><a href="/wiki/Submarine_communications_cable" title="Submarine communications cable">Submarine cables</a></li> <li><a href="/wiki/Voice_over_IP" title="Voice over IP">VoIP</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Calls</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Missed_call" title="Missed call">Missed call</a></li> <li><a href="/wiki/Misdialed_call" title="Misdialed call">Misdialed call</a></li> <li><a href="/wiki/Nuisance_call" title="Nuisance call">Nuisance call</a></li> <li><a href="/wiki/Phone_tag" title="Phone tag">Phone tag</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Applications</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Fax" title="Fax">Fax transmission</a></li> <li><a href="/wiki/Telephone_call" title="Telephone call">Telephone calls</a></li> <li><a href="/wiki/Telephone_newspaper" title="Telephone newspaper">Telephone newspapers</a></li> <li><a href="/wiki/Th%C3%A9%C3%A2trophone" title="Théâtrophone">Théâtrophone</a></li> <li><a href="/wiki/Videotelephony" title="Videotelephony">Video calls</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div><span class="nowrap"><span class="noviewer" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4e/Telecom-icon.svg/28px-Telecom-icon.svg.png" decoding="async" width="28" height="28" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4e/Telecom-icon.svg/42px-Telecom-icon.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4e/Telecom-icon.svg/56px-Telecom-icon.svg.png 2x" data-file-width="500" data-file-height="500" /></span></span> </span><a href="/wiki/Portal:Telecommunication" title="Portal:Telecommunication">Telecommunication portal</a> <span class="nowrap"><span class="noviewer" typeof="mw:File"><span><img alt="telephone icon" src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b8/Telephone_icon_blue_gradient.svg/28px-Telephone_icon_blue_gradient.svg.png" decoding="async" width="28" height="28" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b8/Telephone_icon_blue_gradient.svg/42px-Telephone_icon_blue_gradient.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b8/Telephone_icon_blue_gradient.svg/56px-Telephone_icon_blue_gradient.svg.png 2x" data-file-width="722" data-file-height="722" /></span></span> </span><a href="/wiki/Portal:Telephones" title="Portal:Telephones">Telephones portal</a></div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Telecommunications" style="padding:3px"><table class="nowraplinks hlist mw-collapsible mw-collapsed navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Telecommunications" title="Template:Telecommunications"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Telecommunications" title="Template talk:Telecommunications"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Telecommunications" title="Special:EditPage/Template:Telecommunications"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Telecommunications" style="font-size:114%;margin:0 4em"><a href="/wiki/Telecommunications" title="Telecommunications">Telecommunications</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/History_of_telecommunication" title="History of telecommunication">History</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Beacon#For_defensive_communications" title="Beacon">Beacon</a></li> <li><a href="/wiki/History_of_broadcasting" title="History of broadcasting">Broadcasting</a></li> <li><a href="/wiki/Cable_protection_system" title="Cable protection system">Cable protection system</a></li> <li><a href="/wiki/Cable_television" title="Cable television">Cable TV</a></li> <li><a href="/wiki/Communications_satellite#History" title="Communications satellite">Communications satellite</a></li> <li><a href="/wiki/Computer_network#History" title="Computer network">Computer network</a></li> <li><a href="/wiki/Data_compression" title="Data compression">Data compression</a> <ul><li><a href="/wiki/Audio_coding_format" title="Audio coding format">audio</a></li> <li><a href="/wiki/Discrete_cosine_transform" title="Discrete cosine transform">DCT</a></li> <li><a href="/wiki/Image_compression" title="Image compression">image</a></li> <li><a href="/wiki/Video_coding_format" title="Video coding format">video</a></li></ul></li> <li><a href="/wiki/Digital_media" title="Digital media">Digital media</a> <ul><li><a href="/wiki/Internet_video" title="Internet video">Internet video</a></li> <li><a href="/wiki/Online_video_platform" title="Online video platform">online video platform</a></li> <li><a href="/wiki/Social_media" title="Social media">social media</a></li> <li><a href="/wiki/Streaming_media" title="Streaming media">streaming</a></li></ul></li> <li><a href="/wiki/Drums_in_communication" title="Drums in communication">Drums</a></li> <li><a href="/wiki/Edholm%27s_law" title="Edholm's law">Edholm's law</a></li> <li><a href="/wiki/Electrical_telegraph#History" title="Electrical telegraph">Electrical telegraph</a></li> <li><a href="/wiki/Fax#History" title="Fax">Fax</a></li> <li><a href="/wiki/Heliograph#History" title="Heliograph">Heliographs</a></li> <li><a href="/wiki/Hydraulic_telegraph#Greek_hydraulic_semaphore_system" title="Hydraulic telegraph">Hydraulic telegraph</a></li> <li><a href="/wiki/Information_Age" title="Information Age">Information Age</a></li> <li><a href="/wiki/Information_revolution" class="mw-redirect" title="Information revolution">Information revolution</a></li> <li><a href="/wiki/History_of_the_Internet" title="History of the Internet">Internet</a></li> <li><a href="/wiki/Mass_media#History" title="Mass media">Mass media</a></li> <li><a href="/wiki/History_of_mobile_phones" title="History of mobile phones">Mobile phone</a> <ul><li><a href="/wiki/Smartphone" title="Smartphone">Smartphone</a></li></ul></li> <li><a href="/wiki/Optical_communication" title="Optical communication">Optical telecommunication</a></li> <li><a href="/wiki/Optical_telegraph" title="Optical telegraph">Optical telegraphy</a></li> <li><a href="/wiki/Pager" title="Pager">Pager</a></li> <li><a class="mw-selflink selflink">Photophone</a></li> <li><a href="/wiki/History_of_prepaid_mobile_phones" title="History of prepaid mobile phones">Prepaid mobile phone</a></li> <li><a href="/wiki/History_of_radio" title="History of radio">Radio</a></li> <li><a href="/wiki/Radiotelephone" title="Radiotelephone">Radiotelephone</a></li> <li><a href="/wiki/Communications_satellite" title="Communications satellite">Satellite communications</a></li> <li><a href="/wiki/Semaphore" title="Semaphore">Semaphore</a> <ul><li><a href="/wiki/Phryctoria" title="Phryctoria">Phryctoria</a></li></ul></li> <li><a href="/wiki/Semiconductor" title="Semiconductor">Semiconductor</a> <ul><li><a href="/wiki/Semiconductor_device" title="Semiconductor device">device</a></li> <li><a href="/wiki/MOSFET" title="MOSFET">MOSFET</a></li> <li><a href="/wiki/History_of_the_transistor" title="History of the transistor">transistor</a></li></ul></li> <li><a href="/wiki/Smoke_signal" title="Smoke signal">Smoke signals</a></li> <li><a href="/wiki/History_of_telecommunication" title="History of telecommunication">Telecommunications history</a></li> <li><a href="/wiki/Telautograph" title="Telautograph">Telautograph</a></li> <li><a href="/wiki/Telegraphy" title="Telegraphy">Telegraphy</a></li> <li><a href="/wiki/Teleprinter" title="Teleprinter">Teleprinter</a> (teletype)</li> <li><a href="/wiki/History_of_the_telephone" title="History of the telephone">Telephone</a></li> <li><i><a href="/wiki/The_Telephone_Cases" title="The Telephone Cases">The Telephone Cases</a></i></li> <li><a href="/wiki/History_of_television" title="History of television">Television</a> <ul><li><a href="/wiki/Digital_television" title="Digital television">digital</a></li> <li><a href="/wiki/Streaming_television" title="Streaming television">streaming</a></li></ul></li> <li><a href="/wiki/Submarine_communications_cable#Early_history:_telegraph_and_coaxial_cables" title="Submarine communications cable">Undersea telegraph line</a></li> <li><a href="/wiki/History_of_videotelephony" title="History of videotelephony">Videotelephony</a></li> <li><a href="/wiki/Whistled_language" title="Whistled language">Whistled language</a></li> <li><a href="/wiki/Wireless_revolution" class="mw-redirect" title="Wireless revolution">Wireless revolution</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Pioneers</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Nasir_Ahmed_(engineer)" title="Nasir Ahmed (engineer)">Nasir Ahmed</a></li> <li><a href="/wiki/Edwin_Howard_Armstrong" title="Edwin Howard Armstrong">Edwin Howard Armstrong</a></li> <li><a href="/wiki/Mohamed_M._Atalla" title="Mohamed M. Atalla">Mohamed M. 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Watson">Thomas A. Watson</a></li> <li><a href="/wiki/Charles_Wheatstone" title="Charles Wheatstone">Charles Wheatstone</a></li> <li><a href="/wiki/Vladimir_K._Zworykin" title="Vladimir K. Zworykin">Vladimir K. Zworykin</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Transmission_medium" title="Transmission medium">Transmission<br />media</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Coaxial_cable" title="Coaxial cable">Coaxial cable</a></li> <li><a href="/wiki/Fiber-optic_communication" title="Fiber-optic communication">Fiber-optic communication</a> <ul><li><a href="/wiki/Optical_fiber" title="Optical fiber">optical fiber</a></li></ul></li> <li><a href="/wiki/Free-space_optical_communication" title="Free-space optical communication">Free-space optical communication</a></li> <li><a href="/wiki/Molecular_communication" title="Molecular communication">Molecular communication</a></li> <li><a href="/wiki/Radio_wave" title="Radio wave">Radio waves</a> <ul><li><a href="/wiki/Wireless" title="Wireless">wireless</a></li></ul></li> <li><a href="/wiki/Transmission_line" title="Transmission line">Transmission line</a> <ul><li><a href="/wiki/Telecommunication_circuit" title="Telecommunication circuit">telecommunication circuit</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Network_topology" title="Network topology">Network topology</a><br />and switching</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Bandwidth_(computing)" title="Bandwidth (computing)">Bandwidth</a></li> <li><a href="/wiki/Telecommunications_link" title="Telecommunications link">Links</a></li> <li><a href="/wiki/Node_(networking)" title="Node (networking)">Nodes</a> <ul><li><a href="/wiki/Terminal_(telecommunication)" title="Terminal (telecommunication)">terminal</a></li></ul></li> <li><a href="/wiki/Network_switch" title="Network switch">Network switching</a> <ul><li><a href="/wiki/Circuit_switching" title="Circuit switching">circuit</a></li> <li><a href="/wiki/Packet_switching" title="Packet switching">packet</a></li></ul></li> <li><a href="/wiki/Telephone_exchange" title="Telephone exchange">Telephone exchange</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Multiplexing" title="Multiplexing">Multiplexing</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Space-division_multiple_access" title="Space-division multiple access">Space-division</a></li> <li><a href="/wiki/Frequency-division_multiplexing" title="Frequency-division multiplexing">Frequency-division</a></li> <li><a href="/wiki/Time-division_multiplexing" title="Time-division multiplexing">Time-division</a></li> <li><a href="/wiki/Polarization-division_multiplexing" title="Polarization-division multiplexing">Polarization-division</a></li> <li><a href="/wiki/Orbital_angular_momentum_multiplexing" title="Orbital angular momentum multiplexing">Orbital angular-momentum</a></li> <li><a href="/wiki/Code-division_multiple_access" title="Code-division multiple access">Code-division</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Concepts</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Communication_protocol" title="Communication protocol">Communication protocol</a></li> <li><a href="/wiki/Computer_network" title="Computer network">Computer network</a></li> <li><a href="/wiki/Data_communication" title="Data communication">Data transmission</a></li> <li><a href="/wiki/Store_and_forward" title="Store and forward">Store and forward</a></li> <li><a href="/wiki/Telecommunications_equipment" title="Telecommunications equipment">Telecommunications equipment</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Telecommunications_network" title="Telecommunications network">Types of network</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Cellular_network" title="Cellular network">Cellular network</a></li> <li><a href="/wiki/Ethernet" title="Ethernet">Ethernet</a></li> <li><a href="/wiki/Integrated_Services_Digital_Network" class="mw-redirect" title="Integrated Services Digital Network">ISDN</a></li> <li><a href="/wiki/Local_area_network" title="Local area network">LAN</a></li> <li><a href="/wiki/Mobile_telephony" title="Mobile telephony">Mobile</a></li> <li><a href="/wiki/Next-generation_network" title="Next-generation network">NGN</a></li> <li><a href="/wiki/Public_switched_telephone_network" title="Public switched telephone network">Public Switched Telephone</a></li> <li><a href="/wiki/Radio_network" title="Radio network">Radio</a></li> <li><a href="/wiki/Television_broadcasting" class="mw-redirect" title="Television broadcasting">Television</a></li> <li><a href="/wiki/Telex" title="Telex">Telex</a></li> <li><a href="/wiki/UUCP" title="UUCP">UUCP</a></li> <li><a href="/wiki/Wide_area_network" title="Wide area network">WAN</a></li> <li><a href="/wiki/Wireless_network" title="Wireless network">Wireless network</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Telecommunications_network" title="Telecommunications network">Notable networks</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/ARPANET" title="ARPANET">ARPANET</a></li> <li><a href="/wiki/BITNET" title="BITNET">BITNET</a></li> <li><a href="/wiki/CYCLADES" title="CYCLADES">CYCLADES</a></li> <li><a href="/wiki/FidoNet" title="FidoNet">FidoNet</a></li> <li><a href="/wiki/Internet" title="Internet">Internet</a></li> <li><a href="/wiki/Internet2" title="Internet2">Internet2</a></li> <li><a href="/wiki/JANET" title="JANET">JANET</a></li> <li><a href="/wiki/NPL_network" title="NPL network">NPL network</a></li> <li><a href="/wiki/Toasternet" title="Toasternet">Toasternet</a></li> <li><a href="/wiki/Usenet" title="Usenet">Usenet</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Locations</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Category:Telecommunications_in_Africa" title="Category:Telecommunications in Africa">Africa</a></li> <li>Americas <ul><li><a href="/wiki/Category:Telecommunications_in_North_America" title="Category:Telecommunications in North America">North</a></li> <li><a href="/wiki/Category:Telecommunications_in_South_America" title="Category:Telecommunications in South America">South</a></li></ul></li> <li><a href="/wiki/Category:Communications_in_Antarctica" title="Category:Communications in Antarctica">Antarctica</a></li> <li><a href="/wiki/Category:Telecommunications_in_Asia" title="Category:Telecommunications in Asia">Asia</a></li> <li><a href="/wiki/Category:Telecommunications_in_Europe" title="Category:Telecommunications in Europe">Europe</a></li> <li><a href="/wiki/Category:Telecommunications_in_Oceania" title="Category:Telecommunications in Oceania">Oceania</a></li> <li>(<a href="/wiki/List_of_telecommunications_regulatory_bodies" title="List of telecommunications regulatory bodies">Global telecommunications regulation bodies</a>)</li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div> <ul><li><span class="nowrap"><span class="noviewer" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4e/Telecom-icon.svg/16px-Telecom-icon.svg.png" decoding="async" width="16" height="16" class="mw-file-element" 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