Historical note: Admiral Grace Hopper (an early computing pioneer
better known for inventing {COBOL}) liked to tell a story in
which a technician solved a {glitch} in the Harvard Mark II
machine by pulling an actual insect out from between the contacts
of one of its relays, and she subsequently promulgated {bug} in
its hackish sense as a joke about the incident (though, as she was
careful to admit, she was not there when it happened). For many
years the logbook associated with the incident and the actual bug
in question (a moth) sat in a display case at the Naval Surface
Warfare Center (NSWC). The entire story, with a picture of the
logbook and the moth taped into it, is recorded in the "Annals
of the History of Computing", Vol. 3, No. 3 (July 1981),
pp. 285--286.

The text of the log entry (from September 9, 1947), reads "1545
Relay #70 Panel F (moth) in relay. First actual case of bug being
found". This wording establishes that the term was already
in use at the time in its current specific sense -- and Hopper
herself reports that the term `bug' was regularly applied to
problems in radar electronics during WWII.

Indeed, the use of `bug' to mean an industrial defect was already
established in Thomas Edison's time, and a more specific and rather
modern use can be found in an electrical handbook from 1896
("Hawkin's New Catechism of Electricity", Theo. Audel & Co.)
which says: "The term `bug' is used to a limited extent to
designate any fault or trouble in the connections or working of
electric apparatus." It further notes that the term is "said to
have originated in quadruplex telegraphy and have been transferred