September 11 is Harvey Fletcher’s birthday. Fletcher was an American physicist responsible for many contributions to sound and speech technology.
While working for Bell Telephone Laboratory, Fletcher centered his research into human speech and hearing. He built the first practical audiometer to measure hearing loss and the first electronic hearing aid. He improved the clarity of speech transmission over telephone lines and increased the sensitivity of electronic circuits to convert sound to electrical signals and back again. He also developed an artificial larynx to aid people who lost the ability to speak. What Fletcher is possibly best known for is the invention of stereophonic sound.
One little-known fact about Fletcher was his involvement in Robert Millikan’s famous Oil Drop experiment to determine the charge to mass ratio of the electron. Fletcher moved to Chicago to earn his Ph.D. but did not meet the University of Chicago’s entrance requirements for graduate school. Robert Millikan took convinced Fletcher to come in as a special student where he took the graduate level courses while making up the courses necessary to enter the program. Fletcher managed to complete this all while working as a research assistant and teaching physics at a local high school. Once he was a doctoral candidate, Millikan was his advisor. At the time, Millikan was trying to determine the charge of ions using droplets of water squirted between two charged metal plates. The charged bubbles of water would be suspended in the electric field of the plates, balancing out the effects of gravity. The problem they were having was the water droplets would evaporate too quickly before accurate measurements could be made. Fletcher came up with the idea of using oil instead of water. He set up the experiment and successfully made the determination of the charge to mass ratio of the electron. The experiment produced five published papers. He would receive his doctorate by being the sole author of one of these papers in exchange for Millikan being the sole author of the important paper. Fletcher got his doctorate while Millikan got the 1923 Nobel Prize in Physics. Fletcher did not harbor any bad feelings towards Millikan for being left out of this important work. He felt Millikan had helped him out when no one else had when he came to Chicago and even managed to help him get employment when he needed it to offset the cost of schooling. He felt he wouldn’t have entered graduate school without his influence and help.
Notable Science Events for September 11
1941 – Rudolf Schoenheimer died.
Schoenheimer was a German/American biochemist who introduced the practice of radioactive isotope tagging to trace biochemical processes in a living body. He substituted deuterium for some hydrogen atoms in fat molecules and fed them to lab mice. This allowed him to track the deuterium as it moved through the mouse system. After four days, he found approximately half the fat was stored in the fat tissues of the mice. This was contrary to the belief that fat was constantly being replaced between used and stored fat.
Schoenheimer battled depression most of his life and committed suicide by cyanide poisoning at age 43.
1884 – Harvey Fletcher was born.
1768 – Joseph-Nicolas Delisle died.
Delisle was a French astronomer who measured the distance between the Sun and Earth by timing the time Venus and Mercury travel across the face of the Sun.
He was also the first to propose the circular bands of color around the sun that occasionally appear, also known as ‘sun dogs’ are caused by diffraction of sunlight through water vapor in clouds.
1721 – Rudolph Jacob Camerarius died.
Camerarius was a German botanist and physician who discovered plants have sexes. He identified the stamen as the male and pistil as the female reproductive parts and how pollen is required for the process.