December 31, 1938: The "drunkometer," the first breath test for car drivers, invented by Dr Rolla N. Harger of Indiana University School of Medicine, is officially introduced in Indianapolis. It was the first successful machine for testing human blood alcohol content by breath analysis. By 1948, Harger had begun one-week courses on breath alcohol testing sponsored by the National Safety Council's Committee on Tests for Intoxication. Robert F. Borkenstein, an instructor on the  courses, invented the Breathalyzer, a more practical, highly portable instrument for testing breath alcohol, in 1954.
December 31, 1993: The last research samples of the smallpox virus, one of the world's most dreaded plagues until 1977 when it was declared eradicated is scheduled to be destroyed. However, some scientists wanted to continue research on the virus and stopped the destruction plan. The remaining frozen samples are in Moscow, Russia, and the Center for Disease Control and Prevention, in Atlanta, U.S., ready to make vaccine should it ever again be necessary. The virus is extremely stable: researchers claim that it has not changed in thousands of years.