“What is it—strychnine?” I asked.
“No,” he replied, regarding it thoughtfully with some satisfaction. “That is lead carbonate. There can be no doubt that the turbidity of the water was due to this powder in suspension. A little dissolves in the water, while the scales and incrustations in fine particles are carried along in the current. As a matter of fact the amount necessary to make the water poisonous need not be large.”
He applied a little instrument to the cut ends of the pipe. As I bent over, I could see the needle on its dial deflected just a bit.
“My voltmeter,” he said, reading it, “shows that there is a current of about 1.8 volts passing through this pipe all the time.”
“Electrolysis of water pipes!” I exclaimed, thinking of statements I had heard by engineers. “That’s what they mean by stray or vagabond currents, isn’t it?”
He had seized the lantern and was eagerly following up and down the line of the water pipe. At last he stopped, with a low exclamation, at a point where an electric light wire supplying the Minturn cottage crossed overhead. Fastened inconspicuously to the trunk of a tree which served as a support for the wire was another wire which led down from it and was buried in the ground.
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.