Craig turned up the soft earth as fast as he could, until he reached the pipe at this point.  There was the buried wire wound several times around it.

As quickly and as neatly as he could he inserted a connection between the severed ends of the pipe to restore the flow of water to the houses, turned on the water and covered up the holes he had dug.  Then he unwrapped the package which we had tugged about all day, and in a narrow path between the bushes which led to the point where the wire had tapped the electric light feed he placed in a shallow hole in the ground a peculiar apparatus.

As nearly as I could make it out, it consisted of two flat platforms between which, covered over and projected, was a slip of paper which moved forward, actuated by clockwork, and pressed on by a sort of stylus.  Then he covered it over lightly with dirt so that, unless anyone had been looking for it, it would never be noticed.

It was late when we reached the city again, but Kennedy had one more piece of work and that devolved on me.  All the way down on the train he had been writing and rewriting something.

“Walter,” he said, as the train pulled into the station, “I want that published in to-morrow’s papers.”

I looked over what he had written.  It was one of the most sensational stories I have ever fathered, beginning, “Latest of the victims of the unknown poisoner of whole families in Stratfield, Connecticut, is Miss Isabel Pearcy, whose father, Randall Pearcy, died last week.”

I knew that it was a “plant” of some kind, for so far he had discovered no evidence that Miss Pearcy had been affected.  What his purpose was, I could not guess, but I got the story printed.

The next morning early Kennedy was quietly at work in the laboratory.

“What is this treatment of lead poisoning by electrolysis?” I asked, now that there had come a lull when I might get an intelligible answer.  “How does it work?”

“Brand new, Walter,” replied Kennedy.  “It has been discovered that ions will flow directly through the membranes.”

“Ions?” I repeated.  “What are ions?”

“Travelers,” he answered, smiling, “so named by Faraday from the Greek verb, io, to go.  They are little positive and negative charges of electricity of which molecules are composed.  You know some believe now that matter is really composed of electrical energy.  I think I can explain it best by a simile I use with my classes.  It is as though you had a ballroom in which the dancers in couples represent the neutral molecules.  There are a certain number of isolated ladies and gentlemen—­dissociated ions—­” “Who don’t know these new dances?” I interrupted.

“They all know this dance,” he laughed.  “But, to be serious in the simile, suppose at one end of the room there is a large mirror and at the other a buffet with cigars and champagne.  What happens to the dissociated ions?”