John Drury Clark

John Drury Clark, Ph.D. (August 15, 1907 – July 6, 1988) was an American rocket fuel developer, chemist, and science fiction writer. He was instrumental in the revival of interest in Robert E. Howard's Conan stories and influenced the writing careers of L. Sprague de Camp, Fletcher Pratt, and other authors. Clark was born in Fairbanks, Alaska. He attended the University of Alaska and then the California Institute of Technology in Pasadena, California, from 1927 to 1930, graduating with a B.S. in Physical Chemistry. 

During his last two years at Caltech, his college roommate was future science fiction author L. Sprague de Camp. He received an M.S. from the University of Wisconsin–Madison and, in 1934, a Ph.D. from Stanford University. In 1933 Clark published a novel spiral chart of the periodic system of the chemical elements. Life Magazine used this design for a striking and influential illustration as part of a special number on the elements on 16 May 1949. 

It inspired the artist Edgar Longman, whose mural was a prominent exhibit in the Festival of Britain science exhibition, in London, in 1951. Clark came up with a new version in 1950, but this did not have the same success. Clark moved to Schenectady in Upstate New York in the early 1930s, taking a job with General Electric. A few years later, he moved to New York City. He was living in Philadelphia and working as a research chemist for John Wyeth & Brother of that city in 1943. 

On June 7 that year, he married operatic soprano singer Mildred Baldwin. Their marriage later ended in divorce. From 1949 to his retirement in 1970, Clark developed liquid propellants at the Naval Air Rocket Test Station at Dover, New Jersey (after 1960, this became the Army's Liquid Rocket Propulsion Laboratory of Picatinny Arsenal). His title there was a chief chemist.

In 1962 he married artist Inga Pratt, widow of Fletcher Pratt. Clark was the author of Ignition! An Informal History of Liquid Rocket Propellants (Rutgers University Press, 1972), based on his experiences in the field, which he dedicated to his wife, Inga. It chronicles the development of liquid rocket fuel technology through technical explanations of the work scientists performed and anecdotes about the people involved and the often humorous incidents that took place. Copies of the original edition, now out of print, are rare. 

In May 2018, Rutgers University Press began publishing Ignition! An Informal History of Liquid Rocket Propellants again. During the Clarks' married life, they lived in an "unconventional" house in Newfoundland, in the Green Pond section of Rockaway Township, Morris County, New Jersey, where Clark continued to reside in his later years until his own death. He died on July 6, 1988, after a long illness and series of strokes at St. Clare's Hospital in Denville, New Jersey, near his home.

Clark's papers, consisting of four cubic feet of correspondence, drafts of scientific and science fiction publications, notes, an unpublished typescript memoir, diaries (1923–1984), clippings, and photos, are preserved in the Special Collections at Virginia Tech as part of that repository's Archives of American Aerospace Exploration.