Sir John Ambrose Fleming

         Sir John Ambrose Fleming was born on November 29, 1849 in Lancaster, Lancashire.  Every year he could hear less and less.  He went to University College in London and Cambridge University.  Fleming worked with Thomas Alva Edisonís company. 

Photo Courtesy of the Spark Museum

The Atlantic Ocean
Photo Courtesy of

           Fleming was especially interested in photometry.  Photometry is the study of how much light can be seen with a human eye. 

           Fleming worked with Edison on sending messages across the Atlantic Ocean.  In 1901, Morse telegraph signals were sent over the ocean for the first time!  Morse telegraph signals are messages.  Sending a Morse telegraph message was kind of like sending a text message, but not as fancy.

            Fleming also thought potentiometers were useful.  Potentiometers control how loud a television or radio is.


          Photo courtesy of Michigan State University          

 European Physical Society

Photo Courtesy of the European Physical Society

           Fleming read his papers to the Physical Society for sixty-five years.  Fleming used note takers when he went to the meetings. 


            He was a very good teacher.  However, it was hard for him to answer questions in class.  He could not hear the questions good enough to answer them. To solve this problem Fleming created his own assisted listening device.  He attached earphones to a microphone.  When someone needed to talk to him the person talked into the microphone and he listened with the earphones.

Earphones and Microphone

Photo Courtesy of Microsoft

Diode Vacuum Tube

            The diode vacuum tube was Fleming's most important discovery.  To see how a diode vacuum tube works click here.  This discovery eventually led to the invention of the television, radar, and computer. 

            In 1929 Fleming became a knight.  He died on April 18, 1945.  He was in Sidmouth, Devon, England. 


Fellow of the Royal Society

Hughes Medal

Faraday Medal

Gold Medal of Honor of the Institute of Radio Engineers


Web Links


Brittain, James. (1998). John A. Fleming and the Fleming Valve. In Proceedings of the IEEE. 86(7).

Lang, H. G., & Meath-Lang, B. (1995). Sir John Ambrose Fleming.  In A Biographical Dictionary: Deaf Persons in the Arts and
(pp.122-125). Westport, CT: Greenwood Press.