“Already the psychometer is an actual working fact.  No living man can conceal his emotions from the uncanny instrument.  He may bring the most gigantic of will-powers into play to conceal his inner feelings and the psychometer will record the very work which he makes this will-power do.

“The machine is based upon the fact that experiments have proved that the human body’s resistance to an electrical current is increased with the increase of the emotions.  Dr. Jung, of Zurich, thought that it would be a very simple matter to record these varying emotions, and the psychometer is the result—­simple and crude to-day compared with what we have a right to expect in the future.

“A galvanometer is so arranged that its action swings a mirror from side to side, reflecting a light.  This light falls on a ground-glass scale marked off into centimetres, and the arrow is made to follow the beam of light.  A pen pressing down on a metal drum carrying a long roll of paper revolved by machinery records the variations.  Dr. Guthrie, who had charge of the recording, simply sat in front of the ground glass and with the arrow point followed the reflection of the light as it moved along the scale, in this way making a record on the paper on the drum, which I see he is now holding in his hand.

“Mrs. Willoughby, the subject, and myself, the examiner, sat here, facing each other over this table.  Through those metal domes on which she was to keep her hands she received an electric current so weak that it could not be felt even by the most sensitive nerves.  Now with every increase in her emotion, either while I was putting questions to her or showing her the pictures, whether she showed it outwardly or not, she increased her body’s resistance to the current that was being passed in through her hands.  The increase was felt by the galvanometer connected by wires in the music-room, the mirror swung, the light travelled on the scale, the arrow was moved by Dr. Guthrie, and her varying emotions were recorded indelibly upon the revolving sheet of paper, recorded in such a way as to show their intensity and reveal to the trained scientist much of the mental condition of the subject.”

Kennedy and Dr. Guthrie now conversed in low tones.  Once in a while I could catch a scrap of the conversation—­“not an epileptic,” “no abnormal conformation of the head,” “certain mental defects,” “often the result of sickness or accident.”

“Every time that woman appeared there was a most peculiar disturbance,” remarked Dr. Guthrie as Kennedy took the roll of paper from him and studied it carefully.

At length the light seemed to break through his face.

“Among the various kinds of insanity,” he said, slowly measuring his words, “there is one that manifests itself as an irresistible impulse to steal.  Such terms as neuropath and kleptomaniac are often regarded as rather elegant names for contemptible excuses invented by medical men to cover up stealing.  People are prone to say cynically, ‘Poor man’s sins; rich man’s diseases.’  Yet kleptomania does exist, and it is easy to make it seem like crime when it is really persistent, incorrigible, and irrational stealing.  Often it is so great as to be incurable.  Cases have been recorded of clergymen who were kleptomaniacs and in one instance a dying victim stole the snuffbox of his confessor.