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ArticlesThe First Bug

April 1994 / Commentary / The First Bug

Exposing the myth behind the first bug reveals a few tales

Fred R. Shapiro

Etymological folklore is remarkably persistent. Neither lack of documentation, nor lack of plausibility, nor even outright disproof seems to pose much of an obstacle to the career of a colorful word-story. For example, the term hooker, meaning "prostitute," is frequently said to be derived from the name of a Civil War general. The fact that the OED (Oxford English Dictionary) records the use of hooker in this sense as early as 1845, long before General Hooker came on the scene, has had little impact on the popularity of this tale.

A spurious account of the origin of the computer terms bug ("a defect in hardware or software") and debug ("to eliminate such defects") has become the most popular item of etymological folklore of our time. The legend derives the terms from an actual moth found inside an early computer by the pioneer computer scientist Grace Murray Hopper. A typical recital runs as follows:

"One day in the 1940s, Harvard's famed Mark I--the precursor of today's computers--failed. When the Harvard scientists looked inside, they found a moth that had lodged in the Mark I's circuits. They removed the moth with a pair of tweezers, and from then on, whenever there was a problem with the Mark I, the scientists said they were looking for bugs. The term has stuck through the years." (Dun's Business Month, February 1983)

In some versions, the moth is said to have inspired the scientists to speak from then on of debugging the computer, with bug originating as a later derivative of debug.

This moth myth has been repeated in countless computer dictionaries, textbooks, guides, and histories. Even an ostensibly scholarly journal, the Annals of the History of Computing, has worked hard to promote the story.

I must note that there do es appear to have been a moth found in the Mark II (not the Mark I) by Hopper and her colleagues at Harvard. It is preserved at the Naval Museum in Dahlgren, Virginia, taped to Hopper's log of September 9, 1945. However, the claim that computer defects are called bugs because the moth was found is easily disproved. The OED records such a meaning of bug (4b; "a defect or fault in a machine, plan, or the like") as early as 1889. In that year, the Pall Mall Gazette (March 11) reported that "Mr. Edison...had been up the two previous nights discovering a 'bug' in his phonograph--an expression for solving a difficulty, and implying that some imaginary insect has secreted itself inside and is causing all the trouble."

On November 18, 1878, Edison wrote to Theodore Puskas, "It has been just so in all my inventions. The first step is an intuition--and comes with a burst, then difficulties arise. This thing gives out and then that--"Bugs"--as such little faults and difficulties are called--show themselves and mo nths of anxious watching, study and labor are requisite before commercial success--or failure--is certainly reached" (Matthew Josephson, Edison: A Biography, John Wiley & Sons, 1992, page 198).

It is plain from citations in the OED, the Dictionary of Americanisms, and the 1878 Edison quotation that, moth notwithstanding, the computer term bug was merely a specialized application of a general engineering term dating from the 1800s. This meaning was common enough by 1934 to be recognized in Webster's New International Dictionary: "bug, n...3. A defect in apparatus or its operation...Slang, U.S."

Hopper and her colleagues must have thought the discovery of the moth remarkable because mechanical defects were already called bugs. Her September 9, 1945, log entry, which reads, "First actual case of bug being found," makes this quite clear. Even the verb debug must have predated Mark II, since the OED cites a 1945 use in the Journal of the Royal Aeronautical Society, which was probably preceded by sev eral years of oral use in engineering slang.

The argument is clinched by remarks made by J. Presper Eckert, the coinventor of ENIAC, the first fully electronic digital computer. In an interview in Computerworld (George Harrar, "In the Beginning...," November 3, 1986), Eckert was asked, "Do you know how the term bug originated?" He replied, "I know how Grace Hopper thinks it originated. She tells this fanciful story. As far as I know, this was a term in use by engineers, both mechanical and electrical, for difficulties in the equipment long before Grace Hopper ever heard of any of these things. What it amounts to is that it was a new term to Grace. I've never called her up and told her that that's nuts, but it is nuts. That term was in wide use before then."

Fred R. Shapiro is associate librarian for public services and lecturer in legal research at Yale Law School. He is also the editor of the Oxford Dictionary of American Legal Quotations (Oxford University Press, 1993). He can be rea ched on the Internet at shapiro@, or on BIX c/o "editors."

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