Edison Coined the Word “Bug”

by Owen on August 27, 2013

Many think the phrase “computer bug” came from programmer Grace Hopper in the 1940s when she and her colleagues found a dead moth in a Harvard University computer. They truly found a bug in the system, which, in those times, could cause shorts and circuit problems and effect the computer’s operation in many ways.

But the term “bug” to describe an error or problem in the design or operation of a technical system actually dates back to Thomas Edison, our namesake. He actually coined the phrase almost 140 years ago to describe problems he faced during the process of innovation while working on a way to send multiple signals through a single pair of telegraph wires.

Edison first confronted what he later called a bug when he began developing a telegraph system to transmit and receive up to four separate telegrams on a single wire simultaneously. He developed a process which used changes in current direction and amplitude to send two messages in each direction. But, the solution created a false break in a message’s signal created by the changing polarity when the current switched direction.

Edison developed what he eventually called a “bug trap” to isolate the unwanted break.  In August 1873 he filed a patent caveat which included this bug trap, which eventually became part of his application for  a patent, issued in  1892.

The term itself appeared in his notebooks in 1876 and a  later Edison biography notes frequent use of the term in his notebooks. Referring to his lighting invention work, one entry reads: “Awful lot of bugs still.”

By 1878, Edison joked in a letter to the Wester Union president:

“… I did find a ‘bug’ in my apparatus… It was of the genus ‘callbellum.’ The insect appears to find conditions for its existence in all call apparatus of Telephones.”


This is paraphrased in part from an article in IEEE , the institute, written by Alexander Magoun, an outreach historian with the IEEE History Center and Paul Israel, director and general editor of the Edison Papers—a collection of Thomas Edison’s writings, drawings, and business papers—at Rutgers University, in New Brunswick, N.J. The original article can be found here: http://theinstitute.ieee.org/technology-focus/technology-history/did-you-know-edison-coined-the-term-bug

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