George Wachtell, a scientist who had long worked at the Franklin Institute in Philadelphia, died Dec. 31, 2014. He was 91.

Wachtell graduated from high school at 15, was accepted at MIT, but remained in New York City and attended NYU for two years. He then graduated from MIT in 1943 with a bachelor’s degree in physics. In 1951, he was awarded a Ph.D. in physics from Princeton.

He wrote his Ph.D. dissertation on piezoelectric effects — electricity generated by pressure. For the MIT Radiation Laboratory Series on radar beacons, he was a contributing writer, describing major technical advances in radar by the United States in World War II. Wachtell then was associated with the Franklin Institute as a principal scientist.

The Franklin Institute is a center of science education and research. It was founded in 1824, and is named for Benjamin Franklin. Wachtell made many significant contributions in the fields of thermodynamics, heat transfer, supersonic flow, shock waves, chemical kinetics, optics, interior ballistics, electronics, and combustion phenomena. Author of numerous scholarly papers, he received the Franklin Institute Scientist of the Year award in 1986.

Wachtell is survived by two daughters; three grandchildren; and his companion of many years, Marion Steininger. A son died at age 21 months.

Graduate memorials are prepared by the APGA