In patent language, Psychograph associates the emerging science of lie detection with prior experiments in the mechanical exploitation of automatism, especially the Ouija Board.
See for example the 1891 ouija patent claim by Elijah Bond: "The operation is as follows: The table is placed upon the board, and the hand of the Operator is lightly laid or held on the table, when in a few moments the table will move and point to certain letters on the board, spelling and forming sentences, answering questions put by the operator or any other person that may be present at the time." link )
The idea of the polygraph or the psychograph lay in the belief that the human body would reveal its secrets to mechanical testing with a standard of procedural rigour that would hold up in court.
This presumption was tested, and failed, in the 1923 Frye case in which the court established a standard for managing emerging scientific claims in relation to testing.
Just when a scientific principle or discovery crosses the line between the experimental and the demonstrable stages is difficult to define. Somewhere in this twilight zone the evidential force of the principle must be recognized, and while courts will go a long way in admitting expert testimony deduced from a well-organized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs. We think the systolic blood pressure deception test has not yet gained such standing and scientific recognition among physiological and psychological authorities as would justify the courts in admitting expert testimony deduced from the discovery, development, and experiments thus far made. (Frye v. United States, 293 F.1013 [D.C. Cir. 1923])