Another Urban Legend has grown over the use of a fourth chime; that it is used as a sort of emergency alert. Although it has been used that way, the original purpose of the Fourth Chime, according to an NBC Interdepartmental Correspondence dated Apr 7, 1933, was nearer to a modern pager. “In anticipation of the Spring and Summer months, when many in key positions will not always be available at home telephones, the following Emergency Call System will go into effect…” The memo went on to state personnel on an attached list were to contact the network operator when the four chimes were played. The list included NBC executives as well as members of the Engineering, Press, and Service departments. The four chimes would be played every fifteen minutes over WEAF and WJZ until the desired party contacted the network operator.
The first time the fourth chime was used was in 1937 in response to the Hindenburg dirigible crash. The fourth chime also sounded during the Munich Crisis of 1938, in response to news of the Pearl Harbor attack on Dec 7, 1941, and in the early morning hours of June 6, 1944, the D-Day invasion of Europe. The fourth chime was used throughout WWII:
“The Fourth Chime will ring out again and again from the NBC News room in New York whenever events of utmost significance demand the intensive nationwide coverage of the news the American people have come to expect from the National Broadcasting Company.”
The last time the fourth chime was used was to signify the merger of NBC with GE in 1985.