The Hieronymus Machine

A solid-state rebuild of a curious piece of 20th-century instrumentation — remade with modern components for study, teaching, and open experimentation.

The backstory

Thomas Galen Hieronymus patented the Hieronymus Machine in 1949 (U.S. Patent 2,482,773), and science-fiction editor John W. Campbell later gave it a following through the pages of Astounding Science Fiction. The original brought together a "witness" chamber, a tuning ("rate") dial, a prism-and-probe analyzer, and a stroking touch plate — and it endures as a genuinely intriguing artifact in the history of fringe instrumentation.

Our modern rebuild

Instead of recreating the fragile vacuum-tube original, our version renders the concept as a clean, solid-state analog that any capable maker can build and examine:

• Witness well — a 100 mL Pyrex chamber wound with 22 AWG magnet wire.
• Tuning / rate stage — a 10 kΩ rotary potentiometer with a 1 nF reference capacitor in place of the original prism.
• Amplification — three 2N3904 NPN transistor stages for stable, low-noise solid-state gain.
• Touch plate — a Bakelite sheet with a bifilar coil and a capacitive touch sensor for operator interaction.
• Sensor pad — a spiral pickup, mirroring the original layout.

The project ships with a full KiCad schematic and PCB layout (Enhanced_Hieronymus_Machine), plus a bill of materials drawn from everyday suppliers like DigiKey and Adafruit.

Galvanic skin response: an objective operator interface

The original leaned on a touch ("stick") plate: the operator stroked a surface and reported a felt shift in friction at the tuning point. That cue can’t be quantified or recorded, and it is wide open to the operator’s own expectation and micro-movement (the well-documented ideomotor effect). Our proposal swaps that plate—or runs alongside it—for galvanic skin response (GSR), converting a subjective sensation into an instrument-grade electrophysiological signal.

Why GSR is the right modernization

GSR—also known as electrodermal activity (EDA) or skin conductance—is a mainstream, validated psychophysiological measurement. The eccrine sweat glands of the fingers and palms answer almost entirely to the sympathetic branch of the autonomic nervous system; as arousal rises or falls, sweat-gland activity shifts the skin’s electrical conductance in a way that can be measured, timestamped, and logged. It is the very signal behind biofeedback, polygraphy, and today’s wearable stress monitors.

The E-meter is, in engineering terms, a GSR bridge

The Dianetics / Scientology "E-meter" is, in effect, a Wheatstone-bridge ohmmeter that reads skin galvanic resistance across two hand-held electrodes. Volney Mathison’s electropsychometer (U.S. Patents 2,684,670, 1954 and 2,736,313, 1956) and L. Ron Hubbard’s later E-meter (U.S. Patent 3,290,589, 1966) both describe this bridge-based skin-resistance measurement. Since that bridge is a well-understood, low-voltage, inherently safe way to implement GSR, it makes a natural, proven front end to graft onto the original design. (The historical figures can be viewed at the linked patents; the schematic below is our own representation of the generic, public-domain circuit.)

Our implementation

We drop the Bakelite touch plate (or retain it as a secondary channel) and add a two-electrode GSR front end: electrodes → Wheatstone bridge → instrumentation amplifier → ADC → microcontroller with a digital readout and data logging. Excitation is constant-voltage, current-limited to a few microamps, fully isolated and low-voltage—comfortably inside accepted biofeedback safety practice. Because the tuning ("rate") dial and the GSR trace are logged side by side, any claimed correlation turns into a testable, reproducible dataset instead of an unfalsifiable feeling.

Sources

Hieronymus, U.S. Patent 2,482,773 (1949). Mathison electropsychometer, U.S. Patents 2,684,670 and 2,736,313. Hubbard E-meter, U.S. Patent 3,290,589 (1966). Boucsein, W., Electrodermal Activity, 2nd ed., Springer (2012). Society for Psychophysiological Research EDA committee guidelines, SPR / Psychophysiology. Electrodermal activity overview, NIH / PMC.