“We’ll have to look into it,” agreed Kennedy.  “Meanwhile, would you like to know who your ‘wolf’ is that has been spreading rumours about broadcast?”

“I would indeed,” exclaimed Carton eagerly.  “You were right about the statement I issued.  It had no more effect than so many unspoken words.  The fellow has kept right on.  He even had the nerve to call up Miss Ashton in my name and try to find out whether she had any trace of the missing Betty Blackwell.  How do you suppose they found out that she was interested?”

“Not a very difficult thing,” replied Kennedy.  “Miss Ashton must have told several organizations, and the grafters always watch such societies pretty closely.  What did she say?”

“Nothing,” answered Carton.  “I had thought that they might try something of the sort and fortunately I warned her to disregard any telephone messages unless they came certainly from me.  We agreed on a little secret formula, a sort of password, to be used, and I flatter myself that the ‘wolf’ won’t be able to accomplish much in that direction.  You say you have discovered a clue?  How did you get it?”

Kennedy picked up one of the microphotographs which showed an enlargement of the marks on the phonograph cylinder.  He showed it to us and we gazed curiously at the enigmatic markings, greatly magnified.  To me, it looked like a collection of series of lines.  By close scrutiny I was able to make out that the lines were wavy and more or less continuous, being made up of collections of finer lines,—­lines within lines, as it were.

An analysis of their composition showed that the centre of larger lines was composed of three continuous series of markings which looked, under the lens, for all the world like the impressions of an endless straight series of molar teeth.  Flanking these three tooth-like impressions were other lines—­varying in width and in number—­I should say, about four, both above and below the tooth-like impressions.  When highly magnified one could distinguish roughly parallel parts of what at even a low magnification looked like a single line.

“I have been studying voice analysis lately,” explained Kennedy, “particularly with reference to the singing voice.  Mr. Edison has made thousands and thousands of studies of voices to determine which are scientifically perfect for singing.  That side of it did not interest me particularly.  I have been seeking to use the discovery rather for detective purposes.”

He paused and with a fine needle traced out some of the lines on the photographs before us.

“That,” he went on, “is a highly magnified photograph of a minute section of the phonographic record of the voice that called you up, Carton, as editor of the Wall Street Record.  The upper and lower lines, with long regular waves, are formed by a voice with no overtones.  Those three broader lines in the middle, with rhythmic ripples, show the overtones.”