Today in Technology History
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December 17
The electrical engineer who discovered the ionosphere was born 141 years ago.
Arthur Edwin Kennelly was born on December 17, 1861 in India, where his father worked for the British East India Company. Kennelly was educated at several schools in Britain and continental Europe. He never went to college because he quit school before the age of 14 to work as an office grunt for the Society of Telegraph Engineers. He spent his free time learning about electricity, and was soon hired by a telegraph company which employed him first as a telegraph operator, and later gave him positions requiring greater knowledge and responsibility. He became an expert in the field of underwater cables.
In 1887, Kennelly moved to the U.S. and spent the next six years as one of Thomas Edison's top assistants, an experience he described as "the greatest inspiration of my life." In 1894 he co-founded his own company, an electrical consulting firm.
After radio signals were successfully sent across the Atlantic in 1901, Kennelly carefully studied the results. He realized that the radio waves couldn't have simply hugged the Earth's surface -- they never would have crossed the ocean that way, because of the curvature of Earth. Instead, Kennelly reasoned, the signals must have bounced off a reflective layer in the atmosphere. Along with another scientist who reached the same conclusion at the same time, Kennelly is now credited with discovering the ionosphere.
Although that's Kennelly's main claim to fame, it actually wasn't his most important contribution to the history of technology. He was superb at clearly explaining the math behind electrical engineering, and through his writings he made many theories and equations into understandable and useful tools for an entire generation of electrical engineers.
A proponent of the metric system, Kennelly was also involved in improving electrical notation, and scientific notation in general. He taught at Harvard and MIT, and he led several important scientific societies. He died in 1939.
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