John A. Larson's Polygraph Machine (1921)
Background
John A. Larson (1892 - 1965), a Berkley, CA policer officer with a background in psychology and forensic psychiatry, developed the modern polygraph machine or, as it is more commonly called, the lie detector.
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When it was first used in 1921, it differed from earlier polygraph machines in that Larson's was able to continuously record the subject's blood pressure, pulse rate, and respiration all at the same time. Earlier machines could only record one reading at a time and for short periods of time.
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Larson's associate, Leonarde Keeler (1903 - 1949), also a police officer on the Berkeley, CA force, refined Larson's machine and further developed polygraph-interrogation techniques. Instead of using smoked paper, Keeler used pens which would draw on white paper. Keeler also promoted the use of the polygraph by police departments and for the readings the machines produced to be used in court. Larson, on the other hand, did not advocate for the readings to be admissible in courts of law as he believed them to be inconclusive and open to interpretation errors.
John A. Larson (Image courtesy of Wikipedia.)
Leonarde Keeler (Image courtesy of The Polygraph Museum)
Larson (center) and other officers setting up the polygraph machine. The smoked paper is wrapped around two drums which turn the paper. (Image courtesy of The Polygraph Museum.)
Research
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Prior to the pandemic, Larson's polygraph machine was scheduled to go on display as part of an exhibition highlighting the centennial of its implementation, and the plan for my summer internship was to perform the research and assist with the treatment of the smoked paper. Like so many other institutions, NMAH closed in March 2020 because of the pandemic, and Janice Ellis, Senior Book and Paper Conservator and my supervisor for the internship, was not able to fully examine the object and its current condition. After a very brief examination, Janice was able to determine that the paper on which the readings were recorded was smoked and varnished, that the back of the paper was covered in masking tape, and that previous repairs had been attempted. While in storage, the paper had been kept on the drums around which it would have rotated but the tension that the paper was under was lessened and, as a result, the paper slipped and is now crumpled.
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Although the treatment was put on hold, my task during my virtual summer internship was to discover what sort of varnish was used to make the smoked paper record permanent. Based on what was commercially and widely available at the time, I determined that the varnish is most likely shellac. I also researched how smoked paper was made, other uses for smoked paper, patents, treatment methods of other varnished paper objects, and the mechanics of soot formation. The bibliography I created can be accessed here.
Keeler (left) setting up his modified polygraph machine. It is much smaller than Larson's and uses pens to record the readings. (Image courtesy of Today in History.)