It was plain that Kennedy was confident.  “There are other sources of drugs of the nature used in this case to asphyxiate and kill, but the active principle of all is veratrine.  The point is, veratrine from what source?  The sabadilla is dextro-rotary; the death camas is levo-rotary.  Which is it here?”

As I tried to figure out the ramifications of the case, I could see that it was a cruel situation for one or the other of the girls.  Was one of her lovers the murderer of Anitra’s brother?  Or was her own brother the murderer of Eulalie’s lover?  I looked at the faces before me, now tensely watching Kennedy, forgetful of the wire-like strings which they held in their hands.  I studied Teresa de Leon intently for a while.  She was still the enigma which she had been the first time I saw her.

Kennedy paused long enough to look through the eyepiece again as if to reassure himself finally that he was right.  There was a tantalizing suspense as we waited for the verdict of science on this intensely human tragedy.  Then he turned to the queer instrument over which the needle-hand was moving.

“Though some scientists would call this merely a sensitive form of galvanometer,” he remarked, “it is, to me, more than that.  It registers feelings, emotions.  It has been registering your own every moment that I have been talking.

“But most of all it registers the grand passion.  I might even call it a love meter.  Love might seem to be a subject which could not be investigated.  But even love can be attributed to electrical forces, or, perhaps better, is expressed by the generation of an electric current, as though the attraction between men and women were the giving off of electrons or radiations of one to the other.  I have seen this galvanometer stationary during the ordinary meeting of men and women, yet exhibit all sorts of strange vibrations when true lovers meet.”

Not used to Kennedy’s peculiar methods, they were now on guard, ignorant of the fact that that alone was sufficient to corroborate unescapably any evidence they had already given of their feelings toward each other.

Kennedy passed lightly over the torn and bleeding heart of Eulalie.  But, much as he disliked to do so, he could not so quickly pass Anitra.  In spite of her grief, I could see that she was striving to control herself.  A quick blush suffused her face and her breath came and went faster.

“This record,” went on Kennedy, lowering his voice, “tells me that two men are in love with Anitra Barrios.  I will not say which exhibits the deeper, truer passion.  You shall see for yourself in a moment.  But, more than that, it tells me which of the two she cares for most—­a secret her heart would never permit her lips to disclose.  Nor will I disclose it.

“One of them, with supreme egotism, was so sure that he would win her heart that he plotted this murder of her brother so that she would have the whole estate to bring to him—­a terrible price for a dowry.  My love meter tells me, however, that Anitra has something to say about it yet.  She does not love this man.