Alexander Graham Bell

The Eureka Moment – Bell’s Telephone

 While experimenting with sending multiple tones along a telegraph circuit  Bell noticed that when plucked, a piece of clock spring in a magnetic field, produced sounds from a primitive loudspeaker device in the circuit, and more importantly they contained  a harmonic-rich complex sound. He recognised at that point that there was a possibility that transmission of ‘vocal sounds’ was possible. He concluded from what he had just heard, that good quality speech in the form of "undulatory currents", could be transmitted along wires.

The experiment he was conducting at the time was designed to generate an electrical signal, however it had not performed exactly as planned, but the mishap was to eventually lead to the first products capable of a faithful reproduction of the sound of  the human voice over a distance. Again, the potential of an untoward event had been recognised by an inventor and used in a future development.

It took almost a year of developing and optimising the transmitter and the receiver to the point where they could operate over several tens of metres. This took place despite that at the time Bell’s duties as a teacher of the deaf were quite time-consuming. Bell and his assistant Thomas Watson were able to produce a transmitter and receiver that performed so well at the Centennial exhibition that the demonstrations amazed and impressed people like Joseph Henry and Lord Kelvin.

Serendipity had played a major part in the story; Bell was attempting to send multiple tones down a pair of wires and was generating the on-off electric current with an electrical contact at the end of the oscillating spring, the contacts failed somehow but despite this, a sound could be heard coming from the ‘speaker in the circuit when the reed was plucked.

The original experiments had used magnetic fields generated by by an electro-magnet using current supplied by a battery but Bell saw that permanent magnets would do equally well. The first telephones the Bell company sold had no need of a power source.

Alexander Graham Bell possessed several qualities that helped him in his achievements. His electrical knowledge was rather meagre to start off with, but was being being rapidly developed as he conducted his experiments and was complementing a profound understanding of acoustics.

The wording of the patent also reveals an excellent command of language and beautifully describes the inventive step which is the core concept in the patent. “A method of transmitting vocal sounds by ‘UNDULATORY’ electrical currents rather than ‘PULSATORY’ currents.

I believe that it was mainly his acoustical knowledge that was key to his success. One has only to look at the shape of the acoustic part of the devices shown in the telephone patent to see good design.

Within a year of the plucking of the clock spring, Bell’s electromagnetic telephone was almost a marketable product with intelligible sounds successfully being transmitted over distances in excess of 50 metres.

More on the Invention of the Telephone and the Man

Most people will be surprised to learn that Alexander Graham Bell was not that interested in the company that bore his name and retained only ten shares of the almost 1500 shares given to him. His principal pleasures were teaching the deaf, experimentation and of course invention.  He was unassuming to the extent that he had to be tricked by his wife to attend the big exhibition where his apparatus was being demonstrated.

He was proud of his his father’s invention; Bell’s Visible Speech; a method, using symbols of faithfully describing and transcribing sounds. He also produced a different product bearing the same name but was very different in that it was produced by an instrument of his making, where the output was a graphical representation of speech which displayed the frequency and amplitude components. It was in recognition of producing a Bells Visible Speech version of their language that he had bestowed on him an honorary chieftainship of the Mohawk Nation.

It was his father; Alexander Melville Bell’s  system of symbols that was featured in the film ‘My Fair Lady’ and Shaw’s Pygmalion. The system of representation of sound was said to be so comprehensive that it could even represent a cough or a sneeze.

Bell, the Eugenecist

Bell is regarded as a bit of a bogeyman in some sections of the deaf community as he advocated avoidance of marriage among deaf people, he was aware that some conditions that cause deafness are hereditary, it has even been suggested, quite untruthfully, that he advocated compulsory sterilisation, he did, however believe in Eugenics and was active in the field. As a man of science he also speculated upon the benefits of discouraging exclusive socialising between the deaf and encouraged interacting with hearing folk.

Scottish Ruffian or Telephone Pioneer?

A while back I switched on the television mid way through the always amusing and intelligent Television programme – QI, the presenter put the question to the panel  - “Who invented the telephone?”

The reply ‘Alexander Graham Bell’ was given – NO WRONG! shrieked the quizmaster for it was he, the wordy and wonderful Stephen Fry…..”he was at the time a young engineer working for Western Electric and he learned of the work of a poor Italian, a Mr Meucci and promptly nicked the idea”.

Bell was actually a Professor of Vocal Physiology and the co-founder of the National Geographic Magazine and the Journal ‘Science’. Among the many inventions and contributions to science and technology were the first really successful methods of teaching the profoundly deaf-blind to communicate, achieving the world water speed record in his patented hydrofoil. He also experimented with thermal solar panels and tested out an idea of laying down magnetic information on rotating disks. Another of his accomplishments was breeding a variety of sheep with an extra set of teats, however this was found not to have any benefits at the time.

His patent makes no mention of inventing the telephone, only “Improvements to Telegraphy” He did also seem to have a grasp of modulation systems and even described some of the basics of speech synthesis, in fact the original patent is more to do with the use of sound sources carrying harmonics – or ‘overtones’ as he called them, than it is with transmitting voice.

Much of the recent controversy of whether Meucci is a better candidate for the title of the Inventor of the Telephone hinged upon the incorrect belief that at some point Bell had access to Meucci’s materials. The decisions of US Congress to give the level of credence that it did in 2006 when it recognised Meucci as the "true inventer" of the telephone, may have been influenced by being presented with false information fabricated by the owner of The Globe Corporation.

Although a succesful inventor, Meucci's foray into speech transmission produced a means of transmitting acoustical energy along mainly pre-existing telegraph wires. His idea of overcoming the tendancy to short circuit the telegraphic signals was to insulate the communicaters by sitting them on chairs placed on glass insulaters. A rather shady organisation; the Globe Corporation used Meucci to present concocted documents based closely on Bell's and other's developments These were presented to the court but these were very quickly dismissed, when under questioning Meucci revealed that he lacked a sufficiently good understanding of the principles involved in transmitting speech by electrical means. In all there were just under six hundred individuals and companies laying claim to the invention, some much more plausible than Meucci, and some much worse. At this time Meucci seems to have been in a bad situation and vulnerable and was easily exploited.

It is almost certain that there were several telephony pioneers who had demonstrated electrically powered devices which could carry very low quality speech over a distance but Professor Bell was, in addition to being an inventor and an engineer, a development technician and, he and his extremely able assistant, Watson constructed a device that captured sounds which were reproduced at a fair distance from their source.

The Device

Earlier demonstrations depended on the varying the current analogue of the sound being generated, by the varying resistance of the poor contact between a diaphragm and an adjustable screw contact brought up against it. The sound generated by this means was poor quality, to say the least and was barely intelligible at the best of times, only the resistive liquid microphone of Elisha Gray would have produced moderate quality but with poor intelligibility as it performed poorly over the middle and higher end of the range of frequencies required.

Bell and his assistant Thomas A. Watson, while conducting ‘overtone’ transmission experiments discovered that they did not need to interrupt via a contact, the current flowing in a circuit, for sounds generated by a tuning fork-like vibrating reed, to be heard in a distant transducer. This serendipitous event, like Fleming’s Petri dish contamination, led Bell to eliminate the switch contact and later eliminate the electromagnets and the battery,  the electromagnets were replaced with permanent magnets.

Working from this principle they replaced the resonant device with a non-resonant one; an iron diaphragm and were able to transmit and receive audible speech and music with quite similar devices at both ends.

For the first time ever, full range high quality speech was sent over copper wires. The sound level must have been pretty low but the addition of shaped mouthpiece and earpiece he optimised the acoustic parts of the devices. Having studies acoustics and made models of the human ear Bell understood how to collect, channel and concetrate sound.

I recommend reading the patent. Even those with moderate scientific and technical understanding will grasp the basics, especially after reading these musings.  Bell and his patent agents did a much better job than I could ever hope to do, so reading it is a must.

To become a practical technology, telephony had to wait for the development of  a variable resistance type microphone, the passive device of Bell's produced a low level signal. The crude interruptive devices such as those developed by Reis, Manzetti et al. produced sounds but were not a practical proposition. The solution was the carbon granule microphones of Edison and Emile Berliner. These were in use until a few decades ago, however the permanent magnet earpiece design of Bell and Watson persisted for another eighty or so years.

Bell was fortunate in being located in Boston and having resources to make and have made precision equipment and being able to employ an extremely able assistant. The success of the patent and the company set up to exploit it owed much to Bell’s astute father-in-law and the investors who saw a market for the device. Bell seems to have shunned the business side of the Bell Telephone Corporation.

The Helmholz connection

Bell would probably never have become such a serious an electrical experimenter had he not come across a piece of apparatus made by the great German scientist Herman von Helmholz.

When viewing the device, which used a pulsed electrical current to activate a tuninhg fork Bell made the assumption that electrical currents carrying information on complex sounds were being generated in the system. Later he admitted that he was wrong but he went on to actuall construct equipment which achieved just that. Incidently Helmholz went on to direct one of his students to practically demonstrate some of James Clerk Maxwells theories. The student was a young man called Heinrich Herz.

Herz was able to demonstrate radio frequency electromagnetic energy His experiments led to the use of EM waves for communications. Heinrich Helmholz was thus instrumental in not one but two of the miracles of the age.

What prompted me to add the reference to Helmhoz was reading a comment by the evolutionary biologist Richard Dawkins; he stated that he believed that Hemholz was a greater biologist and psychologist than he was a physicist. 

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