
Hieronymus reached radionics by way of a successful career in the electronics field. Born in 1895, he received his amateur radio license in 1913, served as a radio operator with the American army in the First World War, and went to work after the war with pioneering radio station KDKA, where he helped run the first commercial radio broadcast in history on November 2, 1920. He later spent thirty years working for the Kansas City Power and Light Co., where he pioneered many of the techniques that are now standard practice for electricity distribution. He was a fellow of the American Institute of Electrical Engineers and the Institute of Electrical and Electronic Engineers. Think of him with a slide rule in one hand, a voltmeter in the other, and a pocket protector full of pens in his breast pocket, and you've got the right idea.

Hieronymus pursued further work along the same lines, experimenting extensively with the machine and upgrading it to fit new advances in electronics. He became convinced that it worked by means of a previously unrecognized form of energy, which he termed "eloptic" energy (from "electric" and "optic," because it had some characteristics in common with electricity and others in common with light). 1949, he received U.S. Patent #2,482,773, "Detection of Emanations from Materials and Measurement of the Volumes Thereof," for the firs version of his own radionics device, the Hieronymus machine.

Campbell, mind you, was toward the rationalist end of the science fiction spectrum; his great rival Ray Palmer, the man who invented the New Age movement, was much further into high strangeness (and sold a lot more magazine copies than Campbell ever did). He rejected the wilder end of the paranormal boom that took off in American culture after the Second World War. Convinced by the writings of Dr. J.B. Rhine and other pioneering parapsychologists, however, he accepted the reality of psychic phenomena and used to pen editorials for Astounding discussing the latest advances in parapsychological research. That was how the Hieronymus machine found its way to a wider public.
Campbell discussed the Hieronymus machine in several editorials, and also carried out experiments with several machines of his own. He was convinced that the machine was simply a vehicle for the operator's own psychic abilities, and in an attempt to prove it, made a Hieronymus machine in which the circuitry was replaced by a sheet of paper with the circult diagram on it. This, he found, also yielded results. That led to a falling out between Campbell and Hieronymus, because the latter insisted that whatever Campbell was doing with the symbolic machine, he was not working with eloptic energy.
(Any competent occultist, as it happens, could have told them that they were both right. You can get results by using a symbolic pattern to focus and concentrate the mind -- half of ceremonial magic works that way -- but there is also another factor, distinct from consciousness but closely related to biological life, which has different effects. Still, such distinctions were not always drawn in those days.)

Hieronymus also pioneered the use of radionics in agriculture, creating "earth pipes" that worked with the eloptic energy of the soil, and left a very substantial body of technical literature on that subject under the title "cosmiculture." His methods are still very much in use today. The machine on the right is one of many Hieronymus machines currently available.