Alexander Graham Bell, teacher of the deaf, inventor, scientist (born 3 March 1847 in Edinburgh, Scotland; died 2 August 1922 in Baddeck, NS). Alexander Graham Bell is generally considered second only to Thomas Alva Edison among 19th- and 20th-century inventors and, through their inventions, originators of social change. Bell came from Scotland with his parents in July 1870 to Brantford, Ontario. There he and his father worked as speech therapists for the deaf, which led him to work with how sound was transmitted and received. A scientific approach, an awareness of the electric telegraph, and the invention of a successful microphone led to the invention of the telephone 1874-76 (see also Telecommunications).

In 1871 Bell accepted a position teaching at a school for the deaf in Boston, Massachusetts. He spent summers with the family at Brantford, Ont, retreating there to rest when his tendency to overwork left him exhausted. Bell taught "visible speech" by illustrating, through a series of drawings, how sounds are made, essentially teaching his students to speak by seeing sound. He helped them become aware of the sounds around them by feeling sound vibrations. One teaching aid was a balloon; by clutching one tightly against their chests students could feel sound.

Development of the Telephone

Much of Bell's work can be described as a series of observations leading one to another. His combined interest in sound and communication developed his interest in improving the telegraph, which ultimately led to his success with the telephone. In 1872 he read a newspaper article about the Western Union Company paying a significant sum to the inventor of a telegraph system that could transmit two messages at the same time over one wire. He was excited by the possibilities and inspired by public lectures at the Massachusetts Institute of Technology to duplicate some of Herman Helmholtz's experiments with electrical current.

The Multiple Telegraph

When Bell began to experiment with electrical signals, the telegraph had existed for more than 30 years. Although it was a successful system, the telegraph was limited to receiving and sending one message at a time, using Morse code. Even before coming to Canada, Bell had been intrigued by the idea of using a well-known musical phenomenon to transmit multiple telegraph messages simultaneously. He knew that everything has a natural frequency (how quickly it vibrates) and that a sound's pitch relies on its frequency. By singing into a piano he discovered that varying the pitch of his voice made different piano strings vibrate in return. His observations led to the idea of sending many different messages along a single wire, with identical tuning forks tuned to different frequencies at either end to send and receive, a system he called the "harmonic telegraph."

By October 1874, Bell's research had been so successful that he informed his future father-in-law, Boston attorney Gardiner Greene Hubbard, about the possibility of a multiple telegraph. Hubbard resented the Western Union Telegraph Company's communications monopoly and gave Bell the financial backing he needed. He was joined by leather merchant Thomas Sanders, who was also the father of one of Bell's students. Bell worked on the multiple telegraph with a young electrician, Thomas Watson, but at the same time, he and Watson were exploring an idea that had occurred to him that summer, for a device that would transmit speech electrically. Bell also met with Joseph Henry, director of the Smithsonian Institution, in March 1875 to discuss ideas for the telephone.

Hubbard was not overly impressed by transmitting voices by wire and felt that Bell's work was delaying the development of the multiple telegraph. He gave Bell an ultimatum: choose work on the electrical transmission of speech, or choose Mabel, Hubbard's daughter and Bell's future wife. Bell was determined to have both and wrote to Hubbard on 4 May 1875 about his work and his theories that "a continuous current of electricity passed through a vibrating wire should [induce] a pulsatory the current." Hubbard was won over by Bell's determination and the rejection of his theories by Western Union because of Hubbard's involvement and in favour of Elisha Gray, Bell's biggest rival.

The first major breakthrough occurred on 2 June 1875. Bell and Watson were preparing an experiment with the multiple telegraph by tuning reeds on three sets of transmitters and receivers in different rooms. One of Watson's reeds, affixed too tightly, was stuck to its electromagnet. With the transmitters off, when Watson plucked the reed to free it, Bell heard a twang in his receiver. The plucked reed had induced an undulating current, using residual magnetism, and activated the electromagnets in Bell's receiver. They had inadvertently reproduced sound and proved that tones could vary the strength of an electric current in a wire. The next step was to build a working transmitter with a membrane that could vary electronic currents and a receiver that could reproduce the variations in audible frequencies. Within days Watson had built a primitive telephone.

Flash of Genius

To explore the reception of sound vibrations, Bell constructed an apparatus consisting of a sheet of blackened glass, a mouthpiece and a long wooden lever with a reed on its edge, attached to a stretched membrane. A sound sent down the mouthpiece made the reed move up and down on the membrane, tracing the shape of the vibration. When the membrane proved insufficiently sensitive, ear specialist Dr. Clarence Blake gave Bell a cadaver ear to study. Bell applied his understanding of the human ear to the telephone.

During his summer visit to Brantford in 1874, while watching the currents in the Grand River, Bell reflected on sound waves moving through the air and realized that with electricity, "it would be possible to transmit sounds of any sort" by controlling the intensity of the current. Based on his new insight, he sketched a primitive telephone. Two years later, on 10 March 1876, he spoke into the first telephone, uttering the now-famous instruction to his assistant: "Mr. Watson - come here - I want to see you."

Bell's worked culminated in, not only the birth of the telephone, but the death of the multiple telegraph. The communications potential of being able to "talk with electricity" overcame anything that could be gained by simply increasing the capability of a dot-and- dash system.

After the Telephone

Bell patented the telephone and energetically promoted its commercial development in the US, founding the Bell Telephone Co on 9 Jul 1877. Also in 1877, he married Mabel Gardiner Hubbard (1857-1923), whom he had taught at the school for the deaf in Boston, and embarked on a yearlong honeymoon in Europe. Victory in a number of lawsuits over telephone patents made him rich by age 35. By then he had moved to Washington, DC, to watch over his business interests. In 1890 he bought land at Baddeck, NS, and later built himself a house there named Beinn Bhreagh ("beautiful mountain" in Gaelic).

He might easily have been content with the financial success of his invention. His many laboratory notebooks reveal the depth of the intellectual curiosity that drove him to learn and create. Bell continued to work with his invention after he formed Bell Telephone. He and his assistant, Charles Tainter, developed a device they called the "photophone," which transmitted sound on a beam of light. In 1881 they successfully sent a photophone message nearly 200 metres between two buildings. Bell considered the photophone "the greatest invention [he had] ever made, greater than the telephone."

Bell spent the rest of his life in scientific research, both in person and by paying for the experiments of others. In the US he collaborated with S.P. Langley, builder of a steam-powered aircraft in the 1890s, and funded the early atomic experiments of A.M. Michelson. Bell himself worked on the photoelectric cell, the iron lung, desalination of seawater, and the phonograph, and attempted to breed a "super race" of sheep at Baddeck.

His wife shared his scientific as well as his philanthropic interests. Mabel Bell was a full member of the Aerial Experiment Association, undertook her own horticultural experiments, and with their 2 daughters lobbied from at least 1910 for women's right to vote.

Aerodromes and Hydrodromes

The Aerial Experiment Association was formed by Bell in 1907 in partnership with J.A.D. McCurdy, F.W. Baldwin and a few other young engineers, such as Glenn H. Curtiss, an American builder of motorcycle engines. The United States Army was interested in the development of flight and Lieutenant Thomas Selfridge acted as their observer. After early experiments with man-lifting kites, the AEA turned to gasoline-powered biplanes (which they called "aerodromes") and built several successful aircraft.

The association's first experimental flight was conducted on 6 December 1907. The test aircraft, the Cygnet I, was a large, tetrahedral kite placed on pontoons. Piloted by Selfridge, it was pulled by a steamboat on Bras d'Or Lake and attained a height of 51 metres. It stayed in the air for 7 minutes, but upon landing on the lake the towline failed to release and the kite, along with Selfridge, was submerged. Selfridge was rescued, but the kite was destroyed.

As additional aircraft were developed, the association relocated to Hammondsport, NY, where Curtiss had a machine shop. The association built and flew, with varying success, several aircraft in 1908. They achieved a record on 4 July when Curtiss flew the June Bug to become the first aircraft to fly one kilometre in the western hemisphere, for which the association was awarded the Scientific American Trophy. The June Bug was renamed the Loon in November when the association put it on pontoons to experiment with water take-offs, which was unsuccessful. The flight of the Silver Dart at Baddeck 23 February 1909 is generally accepted as the first powered, heavier-than-air flight in Canada.

The AEA worked simultaneously on "hydrodromes" or hydrofoil boats from 1908. Bell had conceived of the "heavier than water craft" in 1906. The first hydrofoil, the HD-1, achieved speeds of 72 km/h in 1911 and 80 km/h in 1912. The HD-2 broke up. The HD-3 was built in 1913 but a moratorium was imposed on hydrofoil development by WWI. The HD-4, built in 1917, set a world water-speed record of 114.04 km/h in 1919 when the world's fastest steamships travelled at only 48 km/h. That record was not approached by any other boat for more than a decade.

The HD-4 and other Bell memorabilia have been preserved at the national historic site at Baddeck.