Photophone
Encyclopedia
The photophone, also known as a radiophone, was invented jointly by Alexander Graham Bell
and his then-assistant Charles Sumner Tainter
on February 19, 1880, at Bell's 1325 'L' Street laboratory in Washington, D.C. Both were later to become full associates in the Volta Laboratory Association, created and financed by Bell.
Bell believed the Photophone was his most important invention
. The device allowed for the transmission
of both articulated sound
s and normal human conversations on a beam of light
. On April 1, 1880, and also described by plaque as occurring on June 3, Bell's assistant transmitted the world's first wireless telephone
message to him on their newly invented form of telecommunication
, the far advanced precursor to fiber-optic communication
s that came into widespread use during the 1980s. The wireless call was sent from the roof of the Franklin School to the window of Bell's laboratory, some 213 metres (698.8 ft) away.
Of the eighteen patent
s granted in Bell's name alone, and the twelve he shared with his collaborators, four were for the Photophone, which Bell referred to as his 'greatest achievement', writing that the Photophone was "the greatest invention [I have] ever made, greater than the telephone".
Bell transferred the Photophone's rights to the American Bell Telephone Company
in May 1880. The master patent for the Photophone ( Apparatus for Signalling and Communicating, called Photophone), was issued in December 1880, many decades before its principles could be applied to practical applications.
of certain materials by A. E. Becquerel
in 1839. The Photophone used crystalline selenium
cells at the focal point
of its parabolic receiver. This material's electrical resistance
varies inversely with the illumination falling upon it, i.e., its resistance is higher when it is in the dark, and lower when it is exposed to light
. The idea of the Photophone was thus to modulate a light beam: the resulting varying illumination of the receiver would induce a corresponding varying resistance in the selenium cells, which was then used to regenerate the sounds captured by the telephone receiver.
The modulation of the transmitted light beam was done by a mirror made to vibrate by a person's voice: the thin mirror would alternate between concave and convex forms, thus focusing or dispersing the light from the light source. The Photophone functioned similar to the telephone, except that the Photophone used modulated light as a means of transmitting information
, while the telephone relied on a modulated
electrical signal
carried over a conductive wire circuit
.
Bell described it in his writings:
Although the photophone was an important invention, it was many years before the significance of Bell's work was fully recognized. 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, his design failed to protect its transmissions from outdoor interferences
such as clouds, fog, rain, snow and such, that could easily disrupt the transmission of light.
Until the development of modern laser
and fiber-optic technologies for the secure transport of light, factors such as the weather or the lack of light inhibited the widespread use of Bell's invention. Its earliest non-experimental use came with military communication systems during World War II –its key advantage being that its light-based transmissions could not be intercepted by the enemy.
experiment, Bell and Tainter succeeded in communicating clearly over a distance of some 213 meters (about 700 ft.), using plain sunlight
as their light source –practical electrical lighting having only just been invented by Edison
. Tainter, who was on the roof of the Franklin School, spoke to Bell, who was in his laboratory listening and who signaled back to Tainter by waving his hat from the window as had been requested.
The receiver was a parabolic
mirror with selenium
cells at its focal point. Conducted from the roof of the Franklin School to Bell's laboratory at 1325 'L' Street, this was the world's first wireless telephone communication (away from their laboratory), thus making the Photophone the world's earliest known radiophone and wireless telephone systems. The selenium cells in the parabolic receiver had an electrical resistance varying between 100 and 300 Ω (ohms).
such as clouds, fog, rain, snow and even dust storm
s that could easily disrupt the transmission of light. Until the development of pulse-code modulation
in the 1930s, and the modern laser
and optical fiber
technologies of the 1960s and 1970s for the secure transport of light, factors such as the weather and the lack of light inhibited the use of Bell's invention. Nevertheless, not long after its invention laboratories within the Bell System
continued to improve the Photophone in the hope that it could supplement or replace expensive conventional telephone line
s.
However in an era where people heated their homes with fireplaces and local transportation was almost completely horse-drawn—electric utilities had only just started being developed, and the first practical steam autos and battery-powered vehicles were still a decade away—voices emanating from regular 'wired' telephone lines were sometimes viewed with incredulity, the work of possible supernatural forces
. Additionally, the earliest forms of voice-over-radio communications
were decades away from discovery. Thus the social reticence to the Photophone's futuristic form of communications was palpable, as could be discerned in an 1880 New York Times commentary:
(they instead chose Marian, with Daisy as her moniker). He wrote somewhat ecstatically:
Bell later also speculated on the Photophone's possible future applications, writing prior to any perception of the laser
, and which also vaguely foretold fiber-optic telecommunications
: "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." He also pondered its possible scientific use in the spectral analysis
of artificial light sources, star
s and sunspot
s.
. The plaque, which did not acknowledge Tainter's contribution, read:
Alexander Graham Bell
Alexander Graham Bell was an eminent scientist, inventor, engineer and innovator who is credited with inventing the first practical telephone....
and his then-assistant Charles Sumner Tainter
Charles Sumner Tainter
Charles Sumner Tainter was an American scientific instrument maker, engineer and inventor, best known for his collaborations with Alexander Graham Bell, Chichester Bell, Alexander's father-in-law Gardiner Hubbard, and for his significant improvements to Thomas Edison's phonograph, resulting in the...
on February 19, 1880, at Bell's 1325 'L' Street laboratory in Washington, D.C. Both were later to become full associates in the Volta Laboratory Association, created and financed by Bell.
Bell believed the Photophone was his most important invention
Invention
An invention is a novel composition, device, or process. An invention may be derived from a pre-existing model or idea, or it could be independently conceived, in which case it may be a radical breakthrough. In addition, there is cultural invention, which is an innovative set of useful social...
. The device allowed for the transmission
Transmission (telecommunications)
Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...
of both articulated sound
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
s and normal human conversations on a beam of light
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
. On April 1, 1880, and also described by plaque as occurring on June 3, Bell's assistant transmitted the world's first wireless telephone
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
message to him on their newly invented form of telecommunication
Telecommunication
Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...
, the far advanced precursor to fiber-optic communication
Fiber-optic communication
Fiber-optic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber. The light forms an electromagnetic carrier wave that is modulated to carry information...
s that came into widespread use during the 1980s. The wireless call was sent from the roof of the Franklin School to the window of Bell's laboratory, some 213 metres (698.8 ft) away.
Of the eighteen patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....
s granted in Bell's name alone, and the twelve he shared with his collaborators, four were for the Photophone, which Bell referred to as his 'greatest achievement', writing that the Photophone was "the greatest invention [I have] ever made, greater than the telephone".
Bell transferred the Photophone's rights to the American Bell Telephone Company
Bell Telephone Company
The Bell Telephone Company, a common law joint stock company, was organized in Boston, Massachusetts on July 9, 1877 by Alexander Graham Bell's father-in-law Gardiner Greene Hubbard, who also helped organize a sister company — the New England Telephone and Telegraph Company...
in May 1880. The master patent for the Photophone ( Apparatus for Signalling and Communicating, called Photophone), was issued in December 1880, many decades before its principles could be applied to practical applications.
Design and history
Bell and Tainter's invention was based on the discovery of photovoltaic propertiesPhotovoltaics
Photovoltaics is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect. Photovoltaic power generation employs solar panels composed of a number of solar cells containing a photovoltaic material...
of certain materials by A. E. Becquerel
A. E. Becquerel
Alexandre-Edmond Becquerel , known as Edmond Becquerel, was a French physicist who studied the solar spectrum, magnetism, electricity, and optics. He is known for his work in luminescence and phosphorescence. He is credited with the discovery of the photovoltaic effect, the operating principle of...
in 1839. The Photophone used crystalline selenium
Selenium
Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...
cells at the focal point
Focus (optics)
In geometrical optics, a focus, also called an image point, is the point where light rays originating from a point on the object converge. Although the focus is conceptually a point, physically the focus has a spatial extent, called the blur circle. This non-ideal focusing may be caused by...
of its parabolic receiver. This material's electrical resistance
Electrical resistance
The electrical resistance of an electrical element is the opposition to the passage of an electric current through that element; the inverse quantity is electrical conductance, the ease at which an electric current passes. Electrical resistance shares some conceptual parallels with the mechanical...
varies inversely with the illumination falling upon it, i.e., its resistance is higher when it is in the dark, and lower when it is exposed to light
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
. The idea of the Photophone was thus to modulate a light beam: the resulting varying illumination of the receiver would induce a corresponding varying resistance in the selenium cells, which was then used to regenerate the sounds captured by the telephone receiver.
The modulation of the transmitted light beam was done by a mirror made to vibrate by a person's voice: the thin mirror would alternate between concave and convex forms, thus focusing or dispersing the light from the light source. The Photophone functioned similar to the telephone, except that the Photophone used modulated light as a means of transmitting information
Transmitter
In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...
, while the telephone relied on a modulated
Modulation
In electronics and telecommunications, modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal which typically contains information to be transmitted...
electrical signal
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
carried over a conductive wire circuit
Two-wire circuit
In telecommunication, a two-wire circuit is characterized by supporting transmission in two directions simultaneously, as opposed to four-wire circuits, which have separate pairs for transmit and receive. In either case they are twisted pairs. Telephone lines are almost all two wire, while trunks...
.
Bell described it in his writings:
Although the photophone was an important invention, it was many years before the significance of Bell's work was fully recognized. 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, his design failed to protect its transmissions from outdoor interferences
Precipitation (meteorology)
In meteorology, precipitation In meteorology, precipitation In meteorology, precipitation (also known as one of the classes of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation...
such as clouds, fog, rain, snow and such, that could easily disrupt the transmission of light.
Until the development of modern laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
and fiber-optic technologies for the secure transport of light, factors such as the weather or the lack of light inhibited the widespread use of Bell's invention. Its earliest non-experimental use came with military communication systems during World War II –its key advantage being that its light-based transmissions could not be intercepted by the enemy.
World's first wireless telephone communication – April 1880
In their Washington, D.C.Washington, D.C.
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....
experiment, Bell and Tainter succeeded in communicating clearly over a distance of some 213 meters (about 700 ft.), using plain sunlight
Sunlight
Sunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...
as their light source –practical electrical lighting having only just been invented by Edison
Thomas Edison
Thomas Alva Edison was an American inventor and businessman. He developed many devices that greatly influenced life around the world, including the phonograph, the motion picture camera, and a long-lasting, practical electric light bulb. In addition, he created the world’s first industrial...
. Tainter, who was on the roof of the Franklin School, spoke to Bell, who was in his laboratory listening and who signaled back to Tainter by waving his hat from the window as had been requested.
The receiver was a parabolic
Parabolic reflector
A parabolic reflector is a reflective device used to collect or project energy such as light, sound, or radio waves. Its shape is that of a circular paraboloid, that is, the surface generated by a parabola revolving around its axis...
mirror with selenium
Selenium
Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...
cells at its focal point. Conducted from the roof of the Franklin School to Bell's laboratory at 1325 'L' Street, this was the world's first wireless telephone communication (away from their laboratory), thus making the Photophone the world's earliest known radiophone and wireless telephone systems. The selenium cells in the parabolic receiver had an electrical resistance varying between 100 and 300 Ω (ohms).
Public acceptance
Although the Photophone was an important invention, it was many years before the significance of Bell's work was fully recognized. 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 to bloom along busy city boulevards, his design failed to protect its transmissions from outdoor interferencesPrecipitation (meteorology)
In meteorology, precipitation In meteorology, precipitation In meteorology, precipitation (also known as one of the classes of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation...
such as clouds, fog, rain, snow and even dust storm
Dust storm
A dust / sand storm is a meteorological phenomenon common in arid and semi-arid regions. Dust storms arise when a gust front or other strong wind blows loose sand and dirt from a dry surface. Particles are transported by saltation and suspension, causing soil to move from one place and deposition...
s that could easily disrupt the transmission of light. Until the development of pulse-code modulation
Pulse-code modulation
Pulse-code modulation is a method used to digitally represent sampled analog signals. It is the standard form for digital audio in computers and various Blu-ray, Compact Disc and DVD formats, as well as other uses such as digital telephone systems...
in the 1930s, and the modern laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
and optical fiber
Optical fiber
An optical fiber is a flexible, transparent fiber made of a pure glass not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of...
technologies of the 1960s and 1970s for the secure transport of light, factors such as the weather and the lack of light inhibited the use of Bell's invention. Nevertheless, not long after its invention laboratories within the Bell System
Bell System
The Bell System was the American Bell Telephone Company and then, subsequently, AT&T led system which provided telephone services to much of the United States and Canada from 1877 to 1984, at various times as a monopoly. In 1984, the company was broken up into separate companies, by a U.S...
continued to improve the Photophone in the hope that it could supplement or replace expensive conventional telephone line
Telephone line
A telephone line or telephone circuit is a single-user circuit on a telephone communication system...
s.
However in an era where people heated their homes with fireplaces and local transportation was almost completely horse-drawn—electric utilities had only just started being developed, and the first practical steam autos and battery-powered vehicles were still a decade away—voices emanating from regular 'wired' telephone lines were sometimes viewed with incredulity, the work of possible supernatural forces
Supernatural
The supernatural or is that which is not subject to the laws of nature, or more figuratively, that which is said to exist above and beyond nature...
. Additionally, the earliest forms of voice-over-radio communications
History of radio
The early history of radio is the history of technology that produced radio instruments that use radio waves. Within the timeline of radio, many people contributed theory and inventions in what became radio. Radio development began as "wireless telegraphy"...
were decades away from discovery. Thus the social reticence to the Photophone's futuristic form of communications was palpable, as could be discerned in an 1880 New York Times commentary:
"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 telegraph postsUtility poleA utility pole is a pole used to support overhead power lines and various other public utilities, such as cable, fibre optic cable, and related equipment such as transformers and street lights. It can be referred to as a telephone pole, power pole, hydro pole, telegraph pole, or telegraph post,...
, 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 credulityCredulityCredulity is a state of willingness to believe in one or many people or things in the absence of reasonable proof or knowledge.Credulity is not simply belief in something that may be false. The subject of the belief may even be correct, but a credulous person will believe it without good...
."
Sunlight's laughter
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 Mabel BellMabel Gardiner Hubbard
Mabel Gardiner Hubbard , was the daughter of Boston lawyer Gardiner Hubbard—the first president of the Bell Telephone Company...
(they instead chose Marian, with Daisy as her moniker). He wrote somewhat ecstatically:
Bell later also speculated on the Photophone's possible future applications, writing prior to any perception of the laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
, and which also vaguely foretold fiber-optic telecommunications
Fiber-optic communication
Fiber-optic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber. The light forms an electromagnetic carrier wave that is modulated to carry information...
: "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." He also pondered its possible scientific use in the spectral analysis
Spectrum analysis
Spectrum, also known as emission spectrochemical analysis, is the original scientific method of charting and analyzing the chemical properties of matter and gases by looking at the bands in their optical spectrum...
of artificial light sources, star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
s and sunspot
Sunspot
Sunspots are temporary phenomena on the photosphere of the Sun that appear visibly as dark spots compared to surrounding regions. They are caused by intense magnetic activity, which inhibits convection by an effect comparable to the eddy current brake, forming areas of reduced surface temperature....
s.
Commemoration
In 1947 on the centenary of Bell's birth, the Telephone Pioneers of America dedicated a historical marker on the side of one of the buildings, the Franklin School, that Bell and Tainter used for their successful trial, which was also the world's first wireless telecommunicationWireless
Wireless telecommunications is the transfer of information between two or more points that are not physically connected. Distances can be short, such as a few meters for television remote control, or as far as thousands or even millions of kilometers for deep-space radio communications...
. The plaque, which did not acknowledge Tainter's contribution, read:
See also
- Applications of atomic line filters in laser tracking and communication
- Extremely high frequencyExtremely high frequencyExtremely high frequency is the highest radio frequency band. EHF runs the range of frequencies from 30 to 300 gigahertz, above which electromagnetic radiation is considered to be low infrared light, also referred to as terahertz radiation...
- Fiber-optic communicationFiber-optic communicationFiber-optic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber. The light forms an electromagnetic carrier wave that is modulated to carry information...
- Free-space optical communicationFree-space optical communicationFree-space optical communication is an optical communication technology that uses light propagating in free space to transmit data for telecommunications or computer networking."Free space" means air, outer space, vacuum, or something similar...
- History of telecommunicationHistory of telecommunicationThe history of telecommunication began with the use of smoke signals and drums in Africa, the Americas and parts of Asia. In the 1790s, the first fixed semaphore systems emerged in Europe; however it was not until the 1830s that electrical telecommunication systems started to appear...
- IrDAIRDAIRDA may refer to:* Infrared Data Association, in information and communications technology , a standard for communication between devices over short distances using infrared signals...
- Laser microphoneLaser microphoneThe main type of laser microphone is a surveillance device that uses a laser beam to detect sound vibrations in a distant object. The object is typically inside a room where a conversation is taking place, and can be anything that can vibrate in response to the pressure waves created by noises...
- Laser safetyLaser safetyLaser safety is safe design, use and implementation of lasers to minimize the risk of laser accidents, especially those involving eye injuries. Since even relatively small amounts of laser light can lead to permanent eye injuries, the sale and usage of lasers is typically subject to government...
- Laser turntableLaser turntableA laser turntable is a phonograph that uses laser beams as the pickup to play LP gramophone records instead of a stylus .-History:...
- Mie scattering
- Modulating retro-reflectorModulating retro-reflectorA modulating retro-reflector system combines an optical retro-reflector and an optical modulator to allow optical communications and sometimes other functions such as programmable signage....
- Optical windowOptical windowThe meaning of this term depends on the context:* In astronomy, the optical window is the optical portion of the electromagnetic spectrum that passes through the atmosphere all the way to the ground...
- Radio windowRadio windowThe radio window is the range of frequencies of electromagnetic radiation that the earth's atmosphere lets through. The wavelengths in the radio window run from about one centimetre to about eleven-metre waves.-See also:*Astronomical window...
- Rayleigh scatteringRayleigh scatteringRayleigh scattering, named after the British physicist Lord Rayleigh, is the elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the light. The particles may be individual atoms or molecules. It can occur when light travels through...
- Semaphore line
- Smoke signalSmoke signalThe smoke signal is one of the oldest forms of communication in recorded history. It is a form of visual communication used over long distance.-History and usage:...
s - Visible light communication
- Volta Laboratory and Bureau
Further reading
- Most of the bibliographic listings presented are courtesy of Chris Long and Mike Groth's optical audio telecommunications webpage:
- Ackroyd, William. "The Photophone" in "Science for All", Vol. 2 (R. Brown, ed.), Cassell & Co., London, circa 1884, pps. 307 - 312. A popular account, profusely illustrated with steel engravings.
- Armengaud, J. " Le photophone de M.Graham Bell." Soc. Ing. civ. Mem., year 1880, Vol 2. pp. 513–522.
- 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.
- Bell, Alexander Graham. "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 American Journal of Science, 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 ; Journal of the Society of Telegraph Engineers, No. 9, 1880, pps. 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".
- Bell, Alexander Graham. "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.
- Bell, Alexander Graham. "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, pps 220-221 and 2 October 1880 pps 237; Nature (London) Vol 22, 23 September 1880, pps. 500 - 503; Engineering Vol 30, pps 240-242, 253, 254, 407-409; and Journal of the Society of Telegraph Engineers Vol 9, pps 375-387.
- Bell, Alexander Graham. "Other papers on the photophone" E.T.Z. No. 1, 1880, pps 391-396; Journal of the Society for the Arts 1880, No. 28, pps 847-848 & No. 29 pps 60-62; C.R. No. 91, 1880–1881, pps 595-598, 726, 727, 929-931, 982, 1882 pps 409-412, 450, 451, 1224-1227.
- Bell, Alexander Graham. "Le Photophone De La Production Et De La Lumiere." Gauthier-Villars, Imprimeur-Libraire, Paris. 1880. (Note: this is item #26, Folder #4, as noted in "Finding Aid for the Alexander Graham Bell Collection, 1880-1925", Collection number: 308, UCLA Library, Department of Special Collections Manuscripts Division, as viewable at the Online Archive of California)
- "Bell's Photophone." Nature Vol 24, 4 November 1880; The Electrician, Vol. 6, 1881, pps. 136-138.
- Appleton's Journal. "The Photophone." Appleton's Journal, Vol. 10 No. 56, New York, February 1881, pps.181-182.
- Bidwell, Shelford. "The Photophone." Nature., 23. 1881, pp. 58–59.
- 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, pps 158-159 and 29 April 1881 pps. 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).
- Breguet, A. "Les recepteurs photophoniques de selenium." Ann. Chim. Phys., Series 5. Vol 21. 1880, pp..560-563.
- Breguet, A. "Sur les experiences photophonique du Professeur Alexander Graham Bell et de M. Sumner Tainter": C.R.; Vol 91., 1880, pp 595–598.
- Electrician. "Bell's Photophone", Electrician, Vol. 6, 5 February 1881, pps. 136-138,183.
- 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, pps. 212-223.
- Kalischer, S. "Photophon Ohne Batterie." Rep. f. Phys., Vol. 17., 1881, pp. 563–570.
- Mackenzie, Catherine C. "Alexander Graham Bell", Houghton Mifflin Company, Boston, p. 226, 1928.
- Mercadier, E. "La radiophonie indirecte." Lumiere Electrique, Vol. 4, 1881, pps 295-299.
- Mercadier, E. "Sur la radiophonie produite a l'aide du selenium." C. R., Vol 92,1881, pp. 705–707.
- Mercadier, E. "Sur la construction de recepteurs photophoniques a selenium." C. R., Vol 92, 1881, pp. 789–790.
- Mercadier, E. "Sur l'influence de la temperature sur les recepteurs radiophoniques a selenium." C. R., Vol. 92, 1881, pp. 1407–1408.
- Molera & Cebrian. "The Photophone." Eng. L., Vol. 31, 1881, p. 358.
- Preece, Sir William H. "Radiophony", Engineering Vol. 32, 8 July 1881, pps. 29-33; Journal of the Society of Telegraph Engineers, Vol 10, 1881, pps. 212-228. On the photophone.
- Rankine, A.O. "Talking over a Sunbeam." El. Exp. (N. Y.), Vol. 7, 1920, pps. 1265-1316.
- Sternberg, J.M. http://memory.loc.gov/cgi-bin/query/f?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:0:./temp/~ammem_6QVD:The Volta Prize of the French Academy Awarded to Prof. Alexander Graham Bell: A Talk With Dr. J.M. Sternberg], The Evening Traveler, September 1, 1880, The Alexander Graham Bell Papers at the Library of CongressLibrary of CongressThe Library of Congress is the research library of the United States Congress, de facto national library of the United States, and the oldest federal cultural institution in the United States. Located in three buildings in Washington, D.C., it is the largest library in the world by shelf space and...
. Note: a significant portion of the article discusses the Photophone and its possible applications. - Thompson, Silvanus P. "Notes on the Construction of the Photophone." Phys. Soc.Proc., Vol. 4, 1881, pps.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.
- Tomlinson, H. "The Photophone." Nat. L., Vol. 23, 1881, pps. 457-458.
- 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.
- White, R.H. "Photophone." Harmsworth's Wireless Encyclopaedia, Vol. 3, pps. 1541-1544.
- Weinhold, A. "Herstellung von Selenwiderstanden fur Photophonzwecke." E.T.Z., Vol 1, 1880, p. 423.
External links
- Bell's speech before the American Association for the Advancement of ScienceAmerican Association for the Advancement of ScienceThe American Association for the Advancement of Science is an international non-profit organization with the stated goals of promoting cooperation among scientists, defending scientific freedom, encouraging scientific responsibility, and supporting scientific education and science outreach for the...
in BostonBostonBoston is the capital of and largest city in Massachusetts, and is one of the oldest cities in the United States. The largest city in New England, Boston is regarded as the unofficial "Capital of New England" for its economic and cultural impact on the entire New England region. The city proper had...
on August 27, 1880, in which he presented his paper "On the Production and Reproduction of Sound by Light: the Photophone". - Long-distance Atmospheric Optical Communications, by Chris Long and Mike Groth (VK7MJ)