Alexander Graham Bell

Alexander Graham Bell (March 3, 1847 â€" August 2, 1922) was an eminent Scottish-born scientist, inventor, engineer and innovator who is credited with inventing the first practical telephone.

Bell's father, grandfather, and brother had all been associated with work on elocution and speech, and both his mother and wife were deaf, profoundly influencing Bell's life's work. His research on hearing and speech further led him to experiment with hearing devices which eventually culminated in Bell being awarded the first U.S. patent for the telephone in 1876. Bell considered his most famous invention an intrusion on his real work as a scientist and refused to have a telephone in his study.

Many other inventions marked Bell's later life, including groundbreaking work in optical telecommunications, hydrofoils and aeronautics. In 1888, Bell became one of the founding members of the National Geographic Society.

Early life

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Alexander Bell was born in Edinburgh, Scotland, on March 3, 1847. The family home was at 16 South Charlotte Street, and has a stone inscription marking it as Alexander Graham Bell's birthplace. He had two brothers: Melville James Bell (1845â€"70) and Edward Charles Bell (1848â€"67). Both of his brothers died of tuberculosis. His father was Professor Alexander Melville Bell, and his mother was Eliza Grace (née Symonds). Although he was born "Alexander", at age 10, he made a plea to his father to have a middle name like his two brothers. For his 11th birthday, his father acquiesced and allowed him to adopt the middle name "Graham", chosen out of admiration for Alexander Graham, a Canadian being treated by his father and boarder who had become a family friend. To close relatives and friends he remained "Aleck" which his father continued to call him into later life.

First invention

As a child, young Bell displayed a natural curiosity about his world, resulting in gathering botanical specimens as well as experimenting even at an early age. His best friend was Ben Herdman, a neighbor whose family operated a flour mill, the scene of many forays. Young Bell asked what needed to be done at the mill. He was told wheat had to be dehusked through a laborious process and at the age of 12, Bell built a homemade device that combined rotating paddles with sets of nail brushes, creating a simple dehusking machine that was put into operation and used steadily for a number of years. In return, John Herdman gave both boys the run of a small workshop in which to "invent".

From his early years, Bell showed a sensitive nature and a talent for art, poetry, and music that was encouraged by his mother. With no formal training, he mastered the piano and became the family's pianist. Despite being normally quiet and introspective, he reveled in mimicry and "voice tricks" akin to ventriloquism that continually entertained family guests during their occasional visits. Bell was also deeply affected by his mother's gradual deafness, (she began to lose her hearing when he was 12) and learned a manual finger language so he could sit at her side and tap out silently the conversations swirling around the family parlour. He also developed a technique of speaking in clear, modulated tones directly into his mother's forehead wherein she would hear him with reasonable clarity. Bell's preoccupation with his mother's deafness led him to study acoustics.

His family was long associated with the teaching of elocution: his grandfather, Alexander Bell, in London, his uncle in Dublin, and his father, in Edinburgh, were all elocutionists. His father published a variety of works on the subject, several of which are still well known, especially his The Standard Elocutionist (1860), which appeared in Edinburgh in 1868. The Standard Elocutionist appeared in 168 British editions and sold over a quarter of a million copies in the United States alone. In this treatise, his father explains his methods of how to instruct deaf-mutes (as they were then known) to articulate words and read other people's lip movements to decipher meaning. Bell's father taught him and his brothers not only to write Visible Speech but to identify any symbol and its accompanying sound. Bell became so proficient that he became a part of his father's public demonstrations and astounded audiences with his abilities. He could decipher Visible Speech representing virtually every language, including Latin, Scottish Gaelic, and even Sanskrit, accurately reciting written tracts without any prior knowledge of their pronunciation.

Education

As a young child, Bell, like his brothers, received his early schooling at home from his father. At an early age, however, he was enrolled at the Royal High School, Edinburgh, Scotland, which he left at age 15, completing only the first four forms. His school record was undistinguished, marked by absenteeism and lacklustre grades. His main interest remained in the sciences, especially biology, while he treated other school subjects with indifference, to the dismay of his demanding father. Upon leaving school, Bell travelled to London to live with his grandfather, Alexander Bell. During the year he spent with his grandfather, a love of learning was born, with long hours spent in serious discussion and study. The elder Bell took great efforts to have his young pupil learn to speak clearly and with conviction, the attributes that his pupil would need to become a teacher himself. At age 16, Bell secured a position as a "pupil-teacher" of elocution and music, in Weston House Academy, at Elgin, Moray, Scotland. Although he was enrolled as a student in Latin and Greek, he instructed classes himself in return for board and £10 per session. The following year, he attended the University of Edinburgh; joining his older brother Melville who had enrolled there the previous year. In 1868, not long before he departed for Canada with his family, Bell completed his matriculation exams and was accepted for admission to the University of London.

First experiments with sound

His father encouraged Bell’s interest in speech and, in 1863, took his sons to see a unique automaton, developed by Sir Charles Wheatstone based on the earlier work of Baron Wolfgang von Kempelen. The rudimentary "mechanical man" simulated a human voice. Bell was fascinated by the machine and after he obtained a copy of von Kempelen's book, published in German, and had laboriously translated it, he and his older brother Melville built their own automaton head. Their father, highly interested in their project, offered to pay for any supplies and spurred the boys on with the enticement of a "big prize" if they were successful. While his brother constructed the throat and larynx, Bell tackled the more difficult task of recreating a realistic skull. His efforts resulted in a remarkably lifelike head that could "speak", albeit only a few words. The boys would carefully adjust the "lips" and when a bellows forced air through the windpipe, a very recognizable "Mama" ensued, to the delight of neighbors who came to see the Bell invention.

Intrigued by the results of the automaton, Bell continued to experiment with a live subject, the family's Skye Terrier, "Trouve". After he taught it to growl continuously, Bell would reach into its mouth and manipulate the dog's lips and vocal cords to produce a crude-sounding "Ow ah oo ga ma ma". With little convincing, visitors believed his dog could articulate "How are you grandma?" More indicative of his playful nature, his experiments convinced onlookers that they saw a "talking dog". However, these initial forays into experimentation with sound led Bell to undertake his first serious work on the transmission of sound, using tuning forks to explore resonance.

At the age of 19, he wrote a report on his work and sent it to philologist Alexander Ellis, a colleague of his father (who would later be portrayed as Professor Henry Higgins in Pygmalion). Ellis immediately wrote back indicating that the experiments were similar to existing work in Germany, and also lent Bell a copy of Hermann von Helmholtz's work, The Sensations of Tone as a Physiological Basis for the Theory of Music.

Dismayed to find that groundbreaking work had already been undertaken by Helmholtz who had conveyed vowel sounds by means of a similar tuning fork "contraption", he pored over the German scientist's book. Working from his own erroneous mistranslation of a French edition, Bell fortuitously then made a deduction that would be the underpinning of all his future work on transmitting sound, reporting: "Without knowing much about the subject, it seemed to me that if vowel sounds could be produced by electrical means, so could consonants, so could articulate speech." He also later remarked: "I thought that Helmholtz had done it ... and that my failure was due only to my ignorance of electricity. It was a valuable blunder ... If I had been able to read German in those days, I might never have commenced my experiments!"

Family tragedy

In 1865, when the Bell family moved to London, Bell returned to Weston House as an assistant master and, in his spare hours, continued experiments on sound using a minimum of laboratory equipment. Bell concentrated on experimenting with electricity to convey sound and later installed a telegraph wire from his room in Somerset College to that of a friend. Throughout late 1867, his health faltered mainly through exhaustion. His younger brother, Edward "Ted," was similarly bed-ridden, suffering from tuberculosis. While Bell recovered (by then referring to himself in correspondence as "A.G. Bell") and served the next year as an instructor at Somerset College, Bath, England, his brother's condition deteriorated. Edward would never recover. Upon his brother's death, Bell returned home in 1867. His older brother Melville had married and moved out. With aspirations to obtain a degree at the University College London, Bell considered his next years as preparation for the degree examinations, devoting his spare time at his family's residence to studying.

Helping his father in Visible Speech demonstrations and lectures brought Bell to Susanna E. Hull's private school for the deaf in South Kensington, London. His first two pupils were "deaf mute" girls who made remarkable progress under his tutelage. While his older brother seemed to achieve success on many fronts including opening his own elocution school, applying for a patent on an invention, and starting a family, Bell continued as a teacher. However, in May 1870, Melville died from complications due to tuberculosis, causing a family crisis. His father had also suffered a debilitating illness earlier in life and had been restored to health by a convalescence in Newfoundland. Bell's parents embarked upon a long-planned move when they realized that their remaining son was also sickly. Acting decisively, Alexander Melville Bell asked Bell to arrange for the sale of all the family property, conclude all of his brother's affairs (Bell took over his last student, curing a pronounced lisp), and join his father and mother in setting out for the "New World". Reluctantly, Bell also had to conclude a relationship with Marie Eccleston, who, as he had surmised, was not prepared to leave England with him.

Canada

In 1870, at age 23, Bell, his brother's widow, Caroline (Margaret Ottaway), and his parents travelled on the SS Nestorian to Canada. After landing at Quebec City the Bells transferred to another steamer to Montreal and then boarded a train to Paris, Ontario, to stay with the Reverend Thomas Henderson, a family friend. After a brief stay with the Hendersons, the Bell family purchased a farm of 10.5 acres (42,000 m²) at Tutelo Heights (now called Tutela Heights), near Brantford, Ontario. The property consisted of an orchard, large farm house, stable, pigsty, hen-house, and a carriage house, which bordered the Grand River.

At the homestead, Bell set up his own workshop in the converted carriage house near to what he called his "dreaming place", a large hollow nestled in trees at the back of the property above the river. Despite his frail condition upon arriving in Canada, Bell found the climate and environs to his liking, and rapidly improved. He continued his interest in the study of the human voice and when he discovered the Six Nations Reserve across the river at Onondaga, he learned the Mohawk language and translated its unwritten vocabulary into Visible Speech symbols. For his work, Bell was awarded the title of Honorary Chief and participated in a ceremony where he donned a Mohawk headdress and danced traditional dances.

After setting up his workshop, Bell continued experiments based on Helmholtz's work with electricity and sound. He also modified a melodeon (a type of pump organ) so that it could transmit its music electrically over a distance. Once the family was settled in, both Bell and his father made plans to establish a teaching practice and in 1871, he accompanied his father to Montreal, where Melville was offered a position to teach his System of Visible Speech.

Work with the deaf

Bell's father was invited by Sarah Fuller, principal of the Boston School for Deaf Mutes (which continues today as the public Horace Mann School for the Deaf), in Boston, Massachusetts, to introduce the Visible Speech System by providing training for Fuller's instructors, but he declined the post in favor of his son. Traveling to Boston in April 1871, Bell proved successful in training the school's instructors. He was subsequently asked to repeat the program at the American Asylum for Deaf-mutes in Hartford, Connecticut, and the Clarke School for the Deaf in Northampton, Massachusetts.

Returning home to Brantford after six months abroad, Bell continued his experiments with his "harmonic telegraph". The basic concept behind his device was that messages could be sent through a single wire if each message was transmitted at a different pitch, but work on both the transmitter and receiver was needed.

Unsure of his future, he first contemplated returning to London to complete his studies, but decided to return to Boston as a teacher. His father helped him set up his private practice by contacting Gardiner Greene Hubbard, the president of the Clarke School for the Deaf for a recommendation. Teaching his father's system, in October 1872, Alexander Bell opened his "School of Vocal Physiology and Mechanics of Speech" in Boston, which attracted a large number of deaf pupils, with his first class numbering 30 students. While he was working as a private tutor, one of his most famous pupils was Helen Keller, who came to him as a young child unable to see, hear, or speak. She was later to say that Bell dedicated his life to the penetration of that "inhuman silence which separates and estranges." In 1893, Keller performed the sod-breaking ceremony for the construction of the new Bell's new Volta Bureau, dedicated to "the increase and diffusion of knowledge relating to the deaf".

Several influential people of the time, including Bell, viewed deafness as something that should be eradicated, and also believed that with resources and effort they could teach the deaf to speak and avoid the use of sign language, thus enabling their integration within the wider society from which many were often being excluded. In several schools, children were mistreated, for example by having their hands tied behind their backs so they could not communicate by signingâ€"the only language they knewâ€"in an attempt to force them to attempt oral communication. Owing to his efforts to suppress the teaching of sign language, Bell is often viewed negatively by those embracing deaf culture.

Continuing experimentation

In the following year, Bell became professor of Vocal Physiology and Elocution at the Boston University School of Oratory. During this period, he alternated between Boston and Brantford, spending summers in his Canadian home. At Boston University, Bell was "swept up" by the excitement engendered by the many scientists and inventors residing in the city. He continued his research in sound and endeavored to find a way to transmit musical notes and articulate speech, but although absorbed by his experiments, he found it difficult to devote enough time to experimentation. While days and evenings were occupied by his teaching and private classes, Bell began to stay awake late into the night, running experiment after experiment in rented facilities at his boarding house. Keeping "night owl" hours, he worried that his work would be discovered and took great pains to lock up his notebooks and laboratory equipment. Bell had a specially made table where he could place his notes and equipment inside a locking cover. Worse still, his health deteriorated as he suffered severe headaches. Returning to Boston in fall 1873, Bell made a fateful decision to concentrate on his experiments in sound.

Deciding to give up his lucrative private Boston practice, Bell retained only two students, six-year-old "Georgie" Sanders, deaf from birth, and 15-year-old Mabel Hubbard. Each pupil would play an important role in the next developments. George's father, Thomas Sanders, a wealthy businessman, offered Bell a place to stay in nearby Salem with Georgie's grandmother, complete with a room to "experiment". Although the offer was made by George's mother and followed the year-long arrangement in 1872 where her son and his nurse had moved to quarters next to Bell's boarding house, it was clear that Mr. Sanders was backing the proposal. The arrangement was for teacher and student to continue their work together, with free room and board thrown in. Mabel was a bright, attractive girl who was ten years Bell's junior, but became the object of his affection. Having lost her hearing after a near-fatal bout of scarlet fever close to her fifth birthday, she had learned to read lips but her father, Gardiner Greene Hubbard, Bell's benefactor and personal friend, wanted her to work directly with her teacher.

Telephone

By 1874, Bell's initial work on the harmonic telegraph had entered a formative stage, with progress made both at his new Boston "laboratory" (a rented facility) and at his family home in Canada a big success. While working that summer in Brantford, Bell experimented with a "phonautograph", a pen-like machine that could draw shapes of sound waves on smoked glass by tracing their vibrations. Bell thought it might be possible to generate undulating electrical currents that corresponded to sound waves. Bell also thought that multiple metal reeds tuned to different frequencies like a harp would be able to convert the undulating currents back into sound. But he had no working model to demonstrate the feasibility of these ideas.

In 1874, telegraph message traffic was rapidly expanding and in the words of Western Union President William Orton, had become "the nervous system of commerce". Orton had contracted with inventors Thomas Edison and Elisha Gray to find a way to send multiple telegraph messages on each telegraph line to avoid the great cost of constructing new lines. When Bell mentioned to Gardiner Hubbard and Thomas Sanders that he was working on a method of sending multiple tones on a telegraph wire using a multi-reed device, the two wealthy patrons began to financially support Bell's experiments. Patent matters would be handled by Hubbard's patent attorney, Anthony Pollok.

In March 1875, Bell and Pollok visited the famous scientist Joseph Henry, who was then director of the Smithsonian Institution, and asked Henry's advice on the electrical multi-reed apparatus that Bell hoped would transmit the human voice by telegraph. Henry replied that Bell had "the germ of a great invention". When Bell said that he did not have the necessary knowledge, Henry replied, "Get it!" That declaration greatly encouraged Bell to keep trying, even though he did not have the equipment needed to continue his experiments, nor the ability to create a working model of his ideas. However, a chance meeting in 1874 between Bell and Thomas A. Watson, an experienced electrical designer and mechanic at the electrical machine shop of Charles Williams, changed all that.

With financial support from Sanders and Hubbard, Bell hired Thomas Watson as his assistant, and the two of them experimented with acoustic telegraphy. On June 2, 1875, Watson accidentally plucked one of the reeds and Bell, at the receiving end of the wire, heard the overtones of the reed; overtones that would be necessary for transmitting speech. That demonstrated to Bell that only one reed or armature was necessary, not multiple reeds. This led to the "gallows" sound-powered telephone, which could transmit indistinct, voice-like sounds, but not clear speech.

The race to the patent office

In 1875, Bell developed an acoustic telegraph and drew up a patent application for it. Since he had agreed to share U.S. profits with his investors Gardiner Hubbard and Thomas Sanders, Bell requested that an associate in Ontario, George Brown, attempt to patent it in Britain, instructing his lawyers to apply for a patent in the U.S. only after they received word from Britain (Britain would issue patents only for discoveries not previously patented elsewhere).

Meanwhile, Elisha Gray was also experimenting with acoustic telegraphy and thought of a way to transmit speech using a water transmitter. On February 14, 1876, Gray filed a caveat with the U.S. Patent Office for a telephone design that used a water transmitter. That same morning, Bell's lawyer filed Bell's application with the patent office. There is considerable debate about who arrived first and Gray later challenged the primacy of Bell's patent. Bell was in Boston on February 14 and did not arrive in Washington until February 26.

Bell's patent 174,465, was issued to Bell on March 7, 1876, by the U.S. Patent Office. Bell's patent covered "the method of, and apparatus for, transmitting vocal or other sounds telegraphically ... by causing electrical undulations, similar in form to the vibrations of the air accompanying the said vocal or other sound" Bell returned to Boston the same day and the next day resumed work, drawing in his notebook a diagram similar to that in Gray's patent caveat.

On March 10, 1876, three days after his patent was issued, Bell succeeded in getting his telephone to work, using a liquid transmitter similar to Gray's design. Vibration of the diaphragm caused a needle to vibrate in the water, varying the electrical resistance in the circuit. When Bell spoke the famous sentence "Mr. Watsonâ€"Come hereâ€"I want to see you" into the liquid transmitter, Watson, listening at the receiving end in an adjoining room, heard the words clearly.

Although Bell was, and still is, accused of stealing the telephone from Gray, Bell used Gray's water transmitter design only after Bell's patent had been granted, and only as a proof of concept scientific experiment, to prove to his own satisfaction that intelligible "articulate speech" (Bell's words) could be electrically transmitted. After March 1876, Bell focused on improving the electromagnetic telephone and never used Gray's liquid transmitter in public demonstrations or commercial use.

The question of priority for the variable resistance feature of the telephone was raised by the examiner before he approved Bell's patent application. He told Bell that his claim for the variable resistance feature was also described in Gray's caveat. Bell pointed to a variable resistance device in Bell's previous application in which Bell described a cup of mercury, not water. Bell had filed the mercury application at the patent office a year earlier on February 25, 1875, long before Elisha Gray described the water device. In addition, Gray abandoned his caveat, and because he did not contest Bell's priority, the examiner approved Bell's patent on March 3, 1876. Gray had reinvented the variable resistance telephone, but Bell was the first to write down the idea and the first to test it in a telephone.

The patent examiner, Zenas Fisk Wilber, later stated in an affidavit that he was an alcoholic who was much in debt to Bell's lawyer, Marcellus Bailey, with whom he had served in the Civil War. He claimed he showed Gray's patent caveat to Bailey. Wilber also claimed (after Bell arrived in Washington D.C. from Boston) that he showed Gray's caveat to Bell and that Bell paid him $100. Bell claimed they discussed the patent only in general terms, although in a letter to Gray, Bell admitted that he learned some of the technical details. Bell denied in an affidavit that he ever gave Wilber any money.

Later developments

Continuing his experiments in Brantford, Bell brought home a working model of his telephone. On August 3, 1876, from the telegraph office in Mount Pleasant five miles (eight km) away from Brantford, Bell sent a tentative telegram indicating that he was ready. With curious onlookers packed into the office as witnesses, faint voices were heard replying. The following night, he amazed guests as well as his family when a message was received at the Bell home from Brantford, four miles (six km) distant, along an improvised wire strung up along telegraph lines and fences, and laid through a tunnel. This time, guests at the household distinctly heard people in Brantford reading and singing. These experiments clearly proved that the telephone could work over long distances.

Bell and his partners, Hubbard and Sanders, offered to sell the patent outright to Western Union for $100,000. The president of Western Union balked, countering that the telephone was nothing but a toy. Two years later, he told colleagues that if he could get the patent for $25 million he would consider it a bargain. By then, the Bell company no longer wanted to sell the patent. Bell's investors would become millionaires, while he fared well from residuals and at one point had assets of nearly one million dollars.

Bell began a series of public demonstrations and lectures to introduce the new invention to the scientific community as well as the general public. A short time later, his demonstration of an early telephone prototype at the 1876 Centennial Exposition in Philadelphia brought the telephone to international attention. Influential visitors to the exhibition included Emperor Pedro II of Brazil. Later Bell had the opportunity to demonstrate the invention personally to Sir William Thomson (later, Lord Kelvin), a renowned Scottish scientist, as well as to Queen Victoria, who had requested a private audience at Osborne House, her Isle of Wight home. She called the demonstration "most extraordinary". The enthusiasm surrounding Bell's public displays laid the groundwork for universal acceptance of the revolutionary device.

The Bell Telephone Company was created in 1877, and by 1886, more than 150,000 people in the U.S. owned telephones. Bell Company engineers made numerous other improvements to the telephone, which emerged as one of the most successful products ever. In 1879, the Bell company acquired Edison's patents for the carbon microphone from Western Union. This made the telephone practical for longer distances, and it was no longer necessary to shout to be heard at the receiving telephone.

In January 1915, Bell made the first ceremonial transcontinental telephone call. Calling from the AT&T head office at 15 Dey Street in New York City, Bell was heard by Thomas Watson at 333 Grant Avenue in San Francisco. The New York Times reported:

On October 9, 1876, Alexander Graham Bell and Thomas A. Watson talked by telephone to each other over a two-mile wire stretched between Cambridge and Boston. It was the first wire conversation ever held. Yesterday afternoon [on January 25, 1915] the same two men talked by telephone to each other over a 3,400-mile wire between New York and San Francisco. Dr. Bell, the veteran inventor of the telephone, was in New York, and Mr. Watson, his former associate, was on the other side of the continent. They heard each other much more distinctly than they did in their first talk thirty-eight years ago.

Competitors

As is sometimes common in scientific discoveries, simultaneous developments can occur, as evidenced by a number of inventors who were at work on the telephone. Over a period of 18 years, the Bell Telephone Company faced 587 court challenges to its patents, including five that went to the U.S. Supreme Court, but none was successful in establishing priority over the original Bell patent and the Bell Telephone Company never lost a case that had proceeded to a final trial stage. Bell's laboratory notes and family letters were the key to establishing a long lineage to his experiments. The Bell company lawyers successfully fought off myriad lawsuits generated initially around the challenges by Elisha Gray and Amos Dolbear. In personal correspondence to Bell, both Gray and Dolbear had acknowledged his prior work, which considerably weakened their later claims.

On January 13, 1887, the U,S. Government moved to annul the patent issued to Bell on the grounds of fraud and misrepresentation. After a series of decisions and reversals, the Bell company won a decision in the Supreme Court, though a couple of the original claims from the lower court cases were left undecided. By the time that the trial wound its way through nine years of legal battles, the U.S. prosecuting attorney had died and the two Bell patents (No. 174,465 dated March 7, 1876 and No. 186,787 dated January 30, 1877) were no longer in effect, although the presiding judges agreed to continue the proceedings due to the case's importance as a "precedent". With a change in administration and charges of conflict of interest (on both sides) arising from the original trial, the US Attorney General dropped the lawsuit on November 30, 1897 leaving several issues undecided on the merits.

During a deposition filed for the 1887 trial, Italian inventor Antonio Meucci also claimed to have created the first working model of a telephone in Italy in 1834. In 1886, in the first of three cases in which he was involved, Meucci took the stand as a witness in the hopes of establishing his invention's priority. Meucci's evidence in this case was disputed due to a lack of material evidence for his inventions as his working models were purportedly lost at the laboratory of American District Telegraph (ADT) of New York, which was later incorporated as a subsidiary of Western Union in 1901. Meucci's work, like many other inventors of the period, was based on earlier acoustic principles and despite evidence of earlier experiments, the final case involving Meucci was eventually dropped upon Meucci's death. However, due to the efforts of Congressman Vito Fossella, the U.S. House of Representatives on June 11, 2002 stated that Meucci's "work in the invention of the telephone should be acknowledged", even though this did not put an end to a still contentious issue. Some modern scholars do not agree with the claims that Bell's work on the telephone was influenced by Meucci's inventions.

The value of the Bell patent was acknowledged throughout the world, and patent applications were made in most major countries, but when Bell had delayed the German patent application, the electrical firm of Siemens & Halske (S&H) managed to set up a rival manufacturer of Bell telephones under their own patent. The Siemens company produced near-identical copies of the Bell telephone without having to pay royalties. The establishment of the International Bell Telephone Company in Brussels, Belgium in 1880, as well as a series of agreements in other countries eventually consolidated a global telephone operation. The strain put on Bell by his constant appearances in court, necessitated by the legal battles, eventually resulted in his resignation from the company.

Family life

On July 11, 1877, a few days after the Bell Telephone Company was established, Bell married Mabel Hubbard (1857â€"1923) at the Hubbard estate in Cambridge, Massachusetts. His wedding present to his bride was to turn over 1,487 of his 1,497 shares in the newly formed Bell Telephone Company. Shortly thereafter, the newlyweds embarked on a year-long honeymoon in Europe. During that excursion, Bell took a handmade model of his telephone with him, making it a "working holiday". The courtship had begun years earlier; however, Bell waited until he was more financially secure before marrying. Although the telephone appeared to be an "instant" success, it was not initially a profitable venture and Bell's main sources of income were from lectures until after 1897. One unusual request exacted by his fiancée was that he use "Alec" rather than the family's earlier familiar name of "Aleck". From 1876, he would sign his name "Alec Bell". They had four children: Elsie May Bell (1878â€"1964) who married Gilbert Grosvenor of National Geographic fame, Marian Hubbard Bell (1880â€"1962) who was referred to as "Daisy", and two sons who died in infancy (Edward in 1881 and Robert in 1883). The Bell family home was in Cambridge, Massachusetts, until 1880 when Bell's father-in-law bought a house in Washington, D.C., and later in 1882 bought a home in the same city for Bell's family, so that they could be with him while he attended to the numerous court cases involving patent disputes.

Bell was a British subject throughout his early life in Scotland and later in Canada until 1882, when he became a naturalized citizen of the United States. In 1915, he characterized his status as: "I am not one of those hyphenated Americans who claim allegiance to two countries." Despite this declaration, Bell has been proudly claimed as a "native son" by all three countries he resided in: the United States, Canada, and the United Kingdom.

By 1885, a new summer retreat was contemplated. That summer, the Bells had a vacation on Cape Breton Island in Nova Scotia, spending time at the small village of Baddeck. Returning in 1886, Bell started building an estate on a point across from Baddeck, overlooking Bras d'Or Lake. By 1889, a large house, christened The Lodge was completed and two years later, a larger complex of buildings, including a new laboratory, were begun that the Bells would name Beinn Bhreagh (Gaelic: beautiful mountain) after Bell's ancestral Scottish highlands. Bell also built the Bell Boatyard on the estate, employing up to 40 people building experimental craft as well as wartime lifeboats and workboats for the Royal Canadian Navy and pleasure craft for the Bell family. An enthusiastic boater, Bell and his family sailed a rowed a long series of vessels on Bras d'Or Lake, ordering additional vessels from the H.W. Embree and Sons boatyard in Port Hawkesbury, Nova Scotia. In his final, and some of his most productive years, Bell split his residency between Washington, D.C., where he and his family initially resided for most of the year, and at Beinn Bhreagh where they spent increasing amounts of time.

Until the end of his life, Bell and his family would alternate between the two homes, but Beinn Bhreagh would, over the next 30 years, become more than a summer home as Bell became so absorbed in his experiments that his annual stays lengthened. Both Mabel and Bell became immersed in the Baddeck community and were accepted by the villagers as "their own". The Bells were still in residence at Beinn Bhreagh when the Halifax Explosion occurred on December 6, 1917. Mabel and Bell mobilized the community to help victims in Halifax.

Later inventions

Although Alexander Graham Bell is most often associated with the invention of the telephone, his interests were extremely varied. According to one of his biographers, Charlotte Gray, Bell's work ranged "unfettered across the scientific landscape" and he often went to bed voraciously reading the Encyclopædia Britannica, scouring it for new areas of interest. The range of Bell's inventive genius is represented only in part by the 18 patents granted in his name alone and the 12 he shared with his collaborators. These included 14 for the telephone and telegraph, four for the photophone, one for the phonograph, five for aerial vehicles, four for "hydroairplanes" and two for selenium cells. Bell's inventions spanned a wide range of interests and included a metal jacket to assist in breathing, the audiometer to detect minor hearing problems, a device to locate icebergs, investigations on how to separate salt from seawater, and work on finding alternative fuels.

Bell worked extensively in medical research and invented techniques for teaching speech to the deaf. During his Volta Laboratory period, Bell and his associates considered impressing a magnetic field on a record as a means of reproducing sound. Although the trio briefly experimented with the concept, they could not develop a workable prototype. They abandoned the idea, never realizing they had glimpsed a basic principle which would one day find its application in the tape recorder, the hard disc and floppy disc drive and other magnetic media.

Bell's own home used a primitive form of air conditioning, in which fans blew currents of air across great blocks of ice. He also anticipated modern concerns with fuel shortages and industrial pollution. Methane gas, he reasoned, could be produced from the waste of farms and factories. At his Canadian estate in Nova Scotia, he experimented with composting toilets and devices to capture water from the atmosphere. In a magazine interview published shortly before his death, he reflected on the possibility of using solar panels to heat houses.

Photophone

Bell and his assistant Charles Sumner Tainter jointly invented a wireless telephone, named a photophone, which allowed for the transmission of both sounds and normal human conversations on a beam of light. Both men later became full associates in the Volta Laboratory Association.

On June 21, 1880, Bell's assistant transmitted a wireless voice telephone message a considerable distance, from the roof of the Franklin School in Washington, D.C., to Bell at the window of his laboratory, some 213 metres (700 ft) away, 19 years before the first voice radio transmissions.

Bell believed the photophone's principles were his life's "greatest achievement", telling a reporter shortly before his death that the photophone was "the greatest invention [I have] ever made, greater than the telephone". The photophone was a precursor to the fiber-optic communication systems which achieved popular worldwide usage in the 1980s. Its master patent was issued in December 1880, many decades before the photophone's principles came into popular use.

Metal detector

Bell is also credited with the invention of the metal detector in 1881. The device was quickly put together in an attempt to find the bullet in the body of U.S. President James Garfield. According to some accounts, the metal detector worked flawlessly in tests but did not find the assassin's bullet partly because the metal bed frame on which the President was lying disturbed the instrument, resulting in static. The president's surgeons, who were skeptical of the device, ignored Bell's requests to move the president to a bed not fitted with metal springs. Alternatively, although Bell had detected a slight sound on his first test, the bullet may have been lodged too deeply to be detected by the crude apparatus.

Bell's own detailed account, presented to the American Association for the Advancement of Science in 1882, differs in several particulars from most of the many and varied versions now in circulation, most notably by concluding that extraneous metal was not to blame for failure to locate the bullet. Perplexed by the peculiar results he had obtained during an examination of Garfield, Bell "...proceeded to the Executive Mansion the next morning...to ascertain from the surgeons whether they were perfectly sure that all metal had been removed from the neighborhood of the bed. It was then recollected that underneath the horse-hair mattress on which the President lay was another mattress composed of steel wires. Upon obtaining a duplicate, the mattress was found to consist of a sort of net of woven steel wires, with large meshes. The extent of the [area that produced a response from the detector] having been so small, as compared with the area of the bed, it seemed reasonable to conclude that the steel mattress had produced no detrimental effect." In a footnote, Bell adds that "The death of President Garfield and the subsequent post-mortem examination, however, proved that the bullet was at too great a distance from the surface to have affected our apparatus."

Hydrofoils

The March 1906 Scientific American article by American pioneer William E. Meacham explained the basic principle of hydrofoils and hydroplanes. Bell considered the invention of the hydroplane as a very significant achievement. Based on information gained from that article he began to sketch concepts of what is now called a hydrofoil boat. Bell and assistant Frederick W. "Casey" Baldwin began hydrofoil experimentation in the summer of 1908 as a possible aid to airplane takeoff from water. Baldwin studied the work of the Italian inventor Enrico Forlanini and began testing models. This led him and Bell to the development of practical hydrofoil watercraft.

During his world tour of 1910â€"11, Bell and Baldwin met with Forlanini in France. They had rides in the Forlanini hydrofoil boat over Lake Maggiore. Baldwin described it as being as smooth as flying. On returning to Baddeck, a number of initial concepts were built as experimental models, including the Dhonnas Beag, the first self-propelled Bell-Baldwin hydrofoil. The experimental boats were essentially proof-of-concept prototypes that culminated in the more substantial HD-4, powered by Renault engines. A top speed of 54 miles per hour (87 km/h) was achieved, with the hydrofoil exhibiting rapid acceleration, good stability and steering along with the ability to take waves without difficulty. In 1913, Dr. Bell hired Walter Pinaud, a Sydney yacht designer and builder as well as the proprietor of Pinaud's Yacht Yard in Westmount, Nova Scotia to work on the pontoons of the HD-4. Pinaud soon took over the boatyard at Bell Laboratories on Beinn Bhreagh, Bell's estate near Baddeck, Nova Scotia. Pinaud's experience in boat-building enabled him to make useful design changes to the HD-4. After the First World War, work began again on the HD-4. Bell's report to the U.S. Navy permitted him to obtain two 350 horsepower (260 kilowatts) engines in July 1919. On September 9, 1919, the HD-4 set a world marine speed record of 70.86 miles per hour (114.04 kilometres per hour), a record which stood for ten years.

Aeronautics

In 1891, Bell had begun experiments to develop motor-powered heavier-than-air aircraft. The AEA was first formed as Bell shared the vision to fly with his wife, who advised him to seek "young" help as Bell was at the age of 60.

In 1898, Bell experimented with tetrahedral box kites and wings constructed of multiple compound tetrahedral kites covered in maroon silk. The tetrahedral wings were named Cygnet I, II and III, and were flown both unmanned and manned (Cygnet I crashed during a flight carrying Selfridge) in the period from 1907â€"1912. Some of Bell's kites are on display at the Alexander Graham Bell National Historic Site.

Bell was a supporter of aerospace engineering research through the Aerial Experiment Association (AEA), officially formed at Baddeck, Nova Scotia, in October 1907 at the suggestion of his wife Mabel and with her financial support after the sale of some of her real estate. The AEA was headed by Bell and the founding members were four young men: American Glenn H. Curtiss, a motorcycle manufacturer at the time and who held the title "world's fastest man", having ridden his self-constructed motor bicycle around in the shortest time, and who was later awarded the Scientific American Trophy for the first official one-kilometre flight in the Western hemisphere, and who later became a world-renowned airplane manufacturer; Lieutenant Thomas Selfridge, an official observer from the U.S. Federal government and one of the few people in the army who believed that aviation was the future; Frederick W. Baldwin, the first Canadian and first British subject to pilot a public flight in Hammondsport, New York, and J.A.D. McCurdy â€"Baldwin and McCurdy being new engineering graduates from the University of Toronto.

The AEA's work progressed to heavier-than-air machines, applying their knowledge of kites to gliders. Moving to Hammondsport, the group then designed and built the Red Wing, framed in bamboo and covered in red silk and powered by a small air-cooled engine. On March 12, 1908, over Keuka Lake, the biplane lifted off on the first public flight in North America. The innovations that were incorporated into this design included a cockpit enclosure and tail rudder (later variations on the original design would add ailerons as a means of control). One of the AEA's inventions, a practical wingtip form of the aileron, was to become a standard component on all aircraft. The White Wing and June Bug were to follow and by the end of 1908, over 150 flights without mishap had been accomplished. However, the AEA had depleted its initial reserves and only a $15,000 grant from Mrs. Bell allowed it to continue with experiments. Lt. Selfridge had also become the first person killed in a powered heavier-than-air flight in a crash of the Wright Flyer at Fort Myer, Virginia, on September 17, 1908.

Their final aircraft design, the Silver Dart, embodied all of the advancements found in the earlier machines. On February 23, 1909, Bell was present as the Silver Dart flown by J.A.D. McCurdy from the frozen ice of Bras d'Or, made the first aircraft flight in Canada. Bell had worried that the flight was too dangerous and had arranged for a doctor to be on hand. With the successful flight, the AEA disbanded and the Silver Dart would revert to Baldwin and McCurdy who began the Canadian Aerodrome Company and would later demonstrate the aircraft to the Canadian Army.

Eugenics

Bell was connected with the eugenics movement in the United States. In his lecture Memoir upon the formation of a deaf variety of the human race presented to the National Academy of Sciences on November 13, 1883 he noted that congenitally deaf parents were more likely to produce deaf children and tentatively suggested that couples where both parties were deaf should not marry. However, it was his hobby of livestock breeding which led to his appointment to biologist David Starr Jordan's Committee on Eugenics, under the auspices of the American Breeders Association. The committee unequivocally extended the principle to man. From 1912 until 1918 he was the chairman of the board of scientific advisers to the Eugenics Record Office associated with Cold Spring Harbor Laboratory in New York, and regularly attended meetings. In 1921, he was the honorary president of the Second International Congress of Eugenics held under the auspices of the American Museum of Natural History in New York. Organisations such as these advocated passing laws (with success in some states) that established the compulsory sterilization of people deemed to be, as Bell called them, a "defective variety of the human race". By the late 1930s, about half the states in the U.S. had eugenics laws, and California's compulsory sterilization law was used as a model for that of Nazi Germany.

Legacy and honors

Honors and tributes flowed to Bell in increasing numbers as his most famous invention became ubiquitous and his personal fame grew. Bell received numerous honorary degrees from colleges and universities, to the point that the requests almost became burdensome. During his life he also received dozens of major awards, medals and other tributes. These included statuary monuments to both him and the new form of communication his telephone created, notably the Bell Telephone Memorial erected in his honor in Alexander Graham Bell Gardens in Brantford, Ontario, in 1917.

A large number of Bell's writings, personal correspondence, notebooks, papers and other documents reside at both the United States Library of Congress Manuscript Division (as the Alexander Graham Bell Family Papers), and at the Alexander Graham Bell Institute, Cape Breton University, Nova Scotia; major portions of which are available for online viewing.

A number of historic sites and other marks commemorate Bell in North America and Europe, including the first telephone companies of the United States and Canada. Among the major sites are:

• The Alexander Graham Bell National Historic Site, maintained by Parks Canada, which incorporates the Alexander Graham Bell Museum, in Baddeck, Nova Scotia, close to the Bell estate Beinn Bhreagh
• The Bell Homestead National Historic Site, includes the Bell family home, "Melville House", and farm overlooking Brantford, Ontario and the Grand River. It was their first home in North America;
• Canada's first telephone company building, the "Henderson Home" of the late 1870s, a predecessor of the Bell Telephone Company of Canada (officially chartered in 1880). In 1969 the building was carefully moved to the historic Bell Homestead National Historic Site in Brantford, Ontario and was refurbished to become a telephone museum. The Bell Homestead, the Henderson Home telephone museum, and the National Historic Site's reception centre are all maintained by the Bell Homestead Society;
• The Alexander Graham Bell Memorial Park, which features a broad neoclassical monument built in 1917 by public subscription. The monument graphically depicts mankind's ability to span the globe through telecommunications;
• The Alexander Graham Bell Museum (opened in 1956), part of the Alexander Graham Bell National Historic Site which was completed in 1978 in Baddeck, Nova Scotia. Many of the museum's artifacts were donated by Bell's daughters;
  

In 1880, Bell received the Volta Prize with a purse of 50,000 francs (approximately US$250,000 in today's dollars) for the invention of the telephone from the Académie française, representing the French government. Among the luminaries who judged were Victor Hugo and Alexandre Dumas. The Volta Prize was conceived by Napoleon Bonaparte in 1801, and named in honor of Alessandro Volta, with Bell receiving the third grand prize in its history. Since Bell was becoming increasingly affluent, he used his prize money to create endowment funds (the 'Volta Fund') and institutions in and around the United States capital of Washington, D.C.. These included the prestigious 'Volta Laboratory Association' (1880), also known as the Volta Laboratory and as the 'Alexander Graham Bell Laboratory', and which eventually led to the Volta Bureau (1887) as a center for studies on deafness which is still in operation in Georgetown, Washington, D.C. The Volta Laboratory became an experimental facility devoted to scientific discovery, and the very next year it improved Edison's phonograph by substituting wax for tinfoil as the recording medium and incising the recording rather than indenting it, key upgrades that Edison himself later adopted. The laboratory was also the site where he and his associate invented his "proudest achievement", "the photophone", the "optical telephone" which presaged fibre optical telecommunications, while the Volta Bureau would later evolve into the Alexander Graham Bell Association for the Deaf and Hard of Hearing (the AG Bell), a leading center for the research and pedagogy of deafness.

In partnership with Gardiner Hubbard, Bell helped establish the publication Science during the early 1880s. In 1888, Bell was one of the founding members of the National Geographic Society and became its second president (1897â€"1904), and also became a Regent of the Smithsonian Institution (1898â€"1922). The French government conferred on him the decoration of the Légion d'honneur (Legion of Honor); the Royal Society of Arts in London awarded him the Albert Medal in 1902; the University of Würzburg, Bavaria, granted him a PhD, and he was awarded the Franklin Institute's Elliott Cresson Medal in 1912. He was one of the founders of the American Institute of Electrical Engineers in 1884, and served as its president from 1891â€"92. Bell was later awarded the AIEE's Edison Medal in 1914 "For meritorious achievement in the invention of the telephone".

The bel (B) and the smaller decibel (dB) are units of measurement of sound intensity invented by Bell Labs and named after him. Since 1976 the IEEE's Alexander Graham Bell Medal has been awarded to honor outstanding contributions in the field of telecommunications.

In 1936 the US Patent Office declared Bell first on its list of the country's greatest inventors, leading to the US Post Office issuing a commemorative stamp honoring Bell in 1940 as part of its 'Famous Americans Series'. The First Day of Issue ceremony was held on October 28 in Boston, Massachusetts, the city where Bell spent considerable time on research and working with the deaf. The Bell stamp became very popular and sold out in little time. The stamp became, and remains to this day, the most valuable one of the series.

The 150th anniversary of Bell's birth in 1997 was marked by a special issue of commemorative £1 banknotes from the Royal Bank of Scotland. The illustrations on the reverse of the note include Bell's face in profile, his signature, and objects from Bell's life and career: users of the telephone over the ages; an audio wave signal; a diagram of a telephone receiver; geometric shapes from engineering structures; representations of sign language and the phonetic alphabet; the geese which helped him to understand flight; and the sheep which he studied to understand genetics. Additionally, the Government of Canada honored Bell in 1997 with a C$100 gold coin, in tribute also to the 150th anniversary of his birth, and with a silver dollar coin in 2009 in honor of the 100th anniversary of flight in Canada. That first flight was made by an airplane designed under Dr. Bell's tutelage, named the Silver Dart. Bell's image, and also those of his many inventions have graced paper money, coinage and postal stamps in numerous countries worldwide for many dozens of years.

Alexander Graham Bell was ranked 57th among the 100 Greatest Britons (2002) in an official BBC nationwide poll, and among the Top Ten Greatest Canadians (2004), and the 100 Greatest Americans (2005). In 2006 Bell was also named as one of the 10 greatest Scottish scientists in history after having been listed in the National Library of Scotland's 'Scottish Science Hall of Fame'. Bell's name is still widely known and used as part of the names of dozens of educational institutes, corporate namesakes, street and place names around the world.

Honorary degrees

Alexander Graham Bell, who could not complete the university program of his youth, received at least a dozen honorary degrees from academic institutions, including eight honorary LL.D.s (Doctorate of Laws), two Ph.D.s, a D.Sc. and an M.D.:

• Gallaudet College (then named National Deaf-Mute College) in Washington, D.C. (Ph.D.) in 1880
• University of Würzburg in Würzburg, Bavaria (Ph.D.) in 1882
• Heidelberg University in Heidelberg, Germany (M.D.) in 1886
• Harvard University in Cambridge, Massachusetts (LL.D.) in 1896
• Illinois College, in Jacksonville, Illinois (LL.D.) in 1896, possibly 1881
• Amherst College in Amherst, Massachusetts (LL.D.) in 1901
• St. Andrew's University in St Andrews, Scotland (LL.D) in 1902
• University of Oxford in Oxford, England (D.Sc.) in 1906
• University of Edinburgh in Edinburgh, Scotland (LL.D.) in 1906
• George Washington University in Washington, D.C. (LL.D.) in 1913
• Queen's University in Kingston, Ontario, Canada (LL.D.) in 1908
• Dartmouth College in Hanover, New Hampshire (LL.D.) in 1913, possibly 1914

This list is may be incomplete; you can help by expanding it.

Death

Bell died of complications arising from diabetes on August 2, 1922, at his private estate, Beinn Bhreagh, Nova Scotia, at age 75. Bell had also been afflicted with pernicious anemia. His last view of the land he had inhabited was by moonlight on his mountain estate at 2:00 A.M. While tending to him after his long illness, Mabel, his wife, whispered, "Don't leave me." By way of reply, Bell traced the sign for "no" in the air â€"and then he died.

On learning of Bell's death, the Canadian Prime Minister, Mackenzie King, cabled Mrs. Bell, saying:

My colleagues in the Government join with me in expressing to you our sense of the world's loss in the death of your distinguished husband. It will ever be a source of pride to our country that the great invention, with which his name is immortally associated, is a part of its history. On the behalf of the citizens of Canada, may I extend to you an expression of our combined gratitude and sympathy.

Bell's coffin was constructed of Beinn Bhreagh pine by his laboratory staff, lined with the same red silk fabric used in his tetrahedral kite experiments. To help celebrate his life, his wife asked guests not to wear black (the traditional funeral color) while attending his service, during which soloist Jean MacDonald sang a verse of Robert Louis Stevenson's "Requiem":

Under a wide and starry sky,

Dig the grave and let me lie.

Glad did I live and gladly die

And I laid me down with a will.

Upon the conclusion of Bell's funeral, "every phone on the continent of North America was silenced in honor of the man who had given to mankind the means for direct communication at a distance".

Dr. Alexander Graham Bell was buried atop Beinn Bhreagh mountain, on his estate where he had resided increasingly for the last 35 years of his life, overlooking Bras d'Or Lake. He was survived by his wife Mabel, his two daughters, Elsie May and Marian, and nine of his grandchildren.

Quotations

• "In scientific researches, there are no unsuccessful experiments; every experiment contains a lesson. If we don't get the results anticipated and stop right there, it is the man that is unsuccessful, not the experiment."
• "We are all too much inclined, I think, to walk through life with our eyes closed... We should not keep forever on the public road, going only where others have gone; we should leave the beaten track occasionally and enter the woods. Every time you do that you will be certain to find something that you have never seen before.... Follow it up, explore all around it; one discovery will lead to another, and before you know it you will have something worth thinking about to occupy your mind, for all really big discoveries are the results of thought."
• "God has strewn our paths with wonders, and we shall certainly not go through Life with our eyes shut." (1872)
• "To ask the value of speech is like asking the value of life."
• "The inventor is a man who looks around upon the world and is not contented with things as they are. He wants to improve whatever he sees, he wants to benefit the world; he is haunted by an idea. The spirit of invention possesses him, seeking materialization." (1891)
• "I have always considered myself as an Agnostic, but I have now discovered that I am a Unitarian Agnostic." (1901)
• "The day will come when the man at the telephone will be able to see the distant person to whom he is speaking" (c.1906)
• "[It will not be long until] a man can take dinner in New York and breakfast the next morning in Liverpool" (1907). "The nation that secures control of the air will ultimately rule the world" (1908).
• "Every town or city has a vast expanse of roof exposed to the sun. There is no reason why we should not use the roofs of our houses to install solar apparatus to catch and store the heat received from the sun. Solar heat [can be used].... to heat a liquid and store the liquid in an insulated tank... applying even the Thermos bottle principle of a partial vacuum around the tank." (1914)
• "Coal and oil are......strictly limited in quantity. We can take coal out of a mine but we can never put it back." "What shall we do when we have no more coal or oil?" "[The unchecked burning of fossil fuels] would have a sort of greenhouse effect." "The net result is the greenhouse becomes a sort of hot-house."(1917).
• "Self-education is a lifelong affair. There cannot be mental atrophy in any person who continues to observe, to remember what he observes, and to seek answers for his unceasing hows and whys about things."

See also

References

Notes

Citations

Bibliography

External links

• Alexander Graham Bell Institute at Cape Breton University
• Bell Telephone Memorial, Brantford, Ontario
• Bell Homestead National Historic Site, Brantford, Ontario
• Alexander Graham Bell National Historic Site of Canada, Baddeck, Nova Scotia
• Alexander Graham Bell Family Papers at the Library of Congress
• Alexander Graham Bell â€" Biographical Memoirs of the National Academy of Sciences
• Biography at the Dictionary of Canadian Biography Online
• Science.ca profile: Alexander Graham Bell
• Alexander Graham Bell at Answers.com
• Alexander Graham Bell at Find a Grave
• Alexander Graham Bell at the Internet Movie Database

Patents

U.S. patent images in TIFF format

• U.S. Patent 161,739 Improvement in Transmitters and Receivers for Electric Telegraphs, filed March 1875, issued April 1875 (multiplexing signals on a single wire)
• U.S. Patent 174,465 Improvement in Telegraphy, filed February 14, 1876, issued March 7, 1876 (Bell's first telephone patent)
• U.S. Patent 178,399 Improvement in Telephonic Telegraph Receivers, filed April 1876, issued June 1876
• U.S. Patent 181,553 Improvement in Generating Electric Currents (using rotating permanent magnets), filed August 1876, issued August 1876
• U.S. Patent 186,787 Electric Telegraphy (permanent magnet receiver), filed January 15, 1877, issued January 30, 1877
• U.S. Patent 235,199 Apparatus for Signalling and Communicating, called Photophone, filed August 1880, issued December 1880
• U.S. Patent 757,012 Aerial Vehicle, filed June 1903, issued April 1904

Multimedia

• Alexander Graham Bell at The Biography Channel
• The Story of Alexander Graham Bell (1939) at the Internet Movie Database
• Alexander Graham Bell portrayed by John Bach (1992). The Sound and the Silence (Television production). Canada, New Zealand, Ireland: Atlantis Films. 
• The Animated Hero Classics: Alexander Graham Bell (1995) at the Internet Movie Database
• Gray, Charlotte (May 2013). "We Had No Idea What Alexander Graham Bell Sounded Like. Until Now". Smithsonian Magazine.