The film suddenly stopped.  Garrick’s office, which had been ringing with firearms and shouts from the kinetophone, was again silent.  It was an impressive silence, too.  No one of us but had felt and lived the whole case over again in the brief time that the talking movies had been shown.

The lights flashed up, and before we realised that the thing was over, Garrick was standing before us, holding in his hand a long sheet of paper.  The look on his face told plainly that his novel experiment had succeeded.

“I may say,” he began, still studying the paper in his hand, although I knew he must have arrived at his conclusion already or he would never have quitted his “heart station,” so soon, “I may say that some time ago a letter was sent to Miss Winslow purporting to reveal some of Mr. Warrington’s alleged connections and escapades.  It is needless to say that as far as the accusations were concerned he was able to meet them all adequately and, as for the innuendoes, they were pure baseless fabrications.  The sender was urged on to do it by someone else who also had an interest of another kind in placing Mr. Warrington in a bad light with Miss Winslow.  But the sender soon realised his mistake.  The fact that he was willing to go to the length of a dangerous robbery accompanied by arson in order to get back or destroy the letter showed how afraid he was to have a sample of his handwriting fall into my hands.  He blundered, but even then he did not realise how badly.

“For, in certain cases the handwriting shows a great deal more than would be recognised even by the ordinary handwriting expert.  This letter showed that the writer was, as I have already explained to Mr. Marshall, the victim of a peculiar kind of paralysis which begins to show itself in nerve tremours for days before the attack and exhibits itself even in the handwriting.

“Now, my string galvanometer shows not only the effects of these moving and talking pictures on the emotions, but also, as it was really designed to do, the state of the heart with reference to normality.  It shows to me plainly the effect of disease on the heart, even if it is latent in the subject.  While I have been using the psychological law of suggestion, and have been recapitulating as well as I was able under the circumstances the whole story of the crime briefly in moving and talking pictures, I have found, in addition, that the same heart which shows the emotions I expected also shows the disease which I discovered in the blackmailing letter.

“There was surprise at the sight of the gambling den, rage at the raid, fear at the murder of the girl in the other den and the disposal of her body, excitement over the racing motor cars, passion over the kidnapping of the girl, anger over the little detectaphone, and panic at the siege of the bandits, as I showed by the selection of the films that I was getting closer and closer to the truth.  And there was the same abnormality of the heart exhibited throughout.”