Thomas Edison

Thomas Edison

Telephone Transmitter

 

The telephone, invented by Alexander Graham Bell in 1876, converted the sound waves from the human voice to electric impulses, conducted the impulses through a wire, and converted them back to the human sound at the other end of the wire. The originating transmitter contained a parchment membrane that vibrated in response to sound. A metal button attached to the membrane sent the varied movements to an electromagnet and electric current corresponding to the vibrations was induced. This induced current traveled to the receiving device and where the process was reversed, the electricity caused movement of a magnet which then caused a membrane to vibrate and emit the corresponding sounds.

 

Thomas Edison worked to improve a drawback in Bell’s invention: the weakness of the electric signal limited the quality and distance of the message. His approach was to improve the sensitivity of sound detection at the transmitter by replacing the parchment membrane with a disc of compressed carbon set between metal plates. The electrical resistance of carbon is extremely sensitive to the minute pressure changes caused by sound waves. Edison’s solution—improved later by substitution of granulated carbon and then roasting of the granules—became a basic component of telephones for almost a hundred years.

For Thomas Edison, experiencing a failure did not mean that he had failed. Through an examination of the process that led to his invention of the carbon microphone, I argue that his positive approach to failure contributed both to his success as an inventor and to the functional success of his inventions. Edison’s laboratory notebooks and legal testimony reveal that his seemingly erratic approach and reliance on trial and error methods in fact had a consistent direction and a rational basis, well suited to the under-determined problems he faced. The outcome of this process, the carbon microphone, contributed significantly to the commercial success of the telephone and remains in use today. Thomas Hughes has observed that nineteenth century inventors made use of the unexpected behaviour of their inventions as sources of novel phenomena to exploit in new inventions. This paper identifies other ways in which Edison made use of failure and proposes that, paradoxically, the success of technological artefacts can be determined by the thoroughness with which failure is pursued in their creation. It also notes a parallel between Edison’s instrumentalizing of failure and the way in which recent philosophers of science have proposed that scientists should make use of error.