It was his tone rather than his words which gave me the impression that he was more interested in being with Miss Giles than with Mrs.

Cranston. I wondered whether it was a plot of Cranston's and Miss Giles's. Had he been posing before Kennedy, and were they really trying to put Mrs. Cranston out of the way?

As the music started up again, I heard her say, "Can't we have just one more dance?" A moment later they were lost in the gay whirl on the dancing-floor. They made a handsome couple, and it was evident that it was not the first time that they had dined and danced together. The music ceased, and they returned to their places reluctantly, while Cranston telephoned for his car to be brought around to the cabaret.

I hastened back to the laboratory to inform Craig what I had seen. As I told my story he looked up at me with a sudden flash of comprehension.

"I am glad to know where they will all be tonight," he said. "Some one has been giving her henbane--hyoscyamin. I have just discovered it in the tonic."

"What's henbane?" I asked.

"It is a drug derived from the hyoscyamus plant, much like belladonna, though more distinctly sedative. It is a hypnotic used often in mania and mental excitement. The feeling which Mrs. Cranston described is one of its effects. You recall the brightness of her eyes? That is one of the effects of the mydriatic alkaloids, of which this is one. The ancients were familiar with several of its peculiar properties, as they knew of the closely allied poison hemlock.

"Many of the text-books at the present time fail to say anything about the remarkable effect produced by large doses of this terrible alkaloid. This effect can be described technically so as to be intelligible, but no description can convey, even approximately, the terrible sensation produced in many insane patients by large doses. In a general way, it is the condition of paralysis of the body without the corresponding paralysis of the mind."

"And it's this stuff that somebody has been putting into her tonic?" I asked, startled. "Do you suppose that is part of Burr's system, or did Miss Giles lighten her work by putting it into the tonic?"

Kennedy did not betray his suspicion, but went on describing the drug which was having such a serious effect on Mrs. Cranston.

"The victim lies in an absolutely helpless condition sometimes with his muscles so completely paralyzed that he cannot so much as move a finger, cannot close his lips or move his tongue to moisten them. This feeling of helplessness is usually followed by unconsciousness and then by a period of depression. The combined feeling of helplessness and depression is absolutely unlike any other feeling imaginable, if I may judge from the accounts of those who have experienced it. Other sensations, such as pain, may be judged, in a measure, by comparison with other painful sensations, but the sensation produced by hyoscyamin in large doses seems to have no basis for comparison. There is no kindred feeling. Practically every inst.i.tution for the insane used it a few years ago for controlling patients, but now better methods have been devised."

"The more I think of what I saw at the Trocadero," I remarked, "the more I wonder if Miss Giles has been seeking to win Cranston herself."

"In large-enough doses and repeated often enough," continued Kennedy, "I suppose the toxic effect of the drug might be to produce insanity.

At any rate, if we are going to do anything, it might better be done at once. They are all out there now. If we act to-night, surely we shall have the best chance of making the guilty person betray himself."

Kennedy telephoned for a fast touring-car, and in half an hour, while he gathered some apparatus together, the car was before the door. In it he placed a couple of light silk-rope ladders, some common wooden wedges, and an instrument which resembled a surveyor's transit with two conical horns sticking out at the ends.

We made the trip out of New York and up the Boston post-road, following the route which Cranston and Miss Giles must have taken some hours before us. In the town of Montrose, Kennedy stopped only long enough to get a bite to eat and to study up in the roads in the vicinity.

It was long after midnight when we struck up into the country. The night was very dark, thick, and foggy. With the engine running as m.u.f.fled as possible and the lights dimmed, Kennedy quietly jammed on the brakes as we pulled up along the side of the road.

A few rods farther ahead I could make out the Belleclaire Sanatorium surrounded by its picketed stone wall. Not a light was visible in any of the windows.

"Now that we're here," I whispered, "what can we do?"

"You remember the paper I gave Mrs. Cranston when the excitement in the hall broke loose?"

"Yes," I nodded, as we moved over under the shadow of the wall.

"I wrote on a sheet from my note-book," said Kennedy, "and told her to be ready when she heard a pebble strike the window; and I gave her a piece of string to let down to the ground."

Kennedy threw the silk ladder up until it caught on one of the pickets; then, with the other ladder and the wedges, he reached the top of the wall, followed by me. We pulled the first ladder up as we clung to the pickets, and let it down again inside. Noiselessly we crossed the lawn.

Above was Mrs. Cranston's window. Craig picked up some bits of broken stone from a walk about the house and threw them gently against the pane. Then we drew back into the shadow of the house, lest any prying eyes might discover us. In a few minutes the window on the second floor was stealthily opened. The m.u.f.fled figure of Mrs. Cranston appeared in the dim light; then a piece of string was lowered.

To it Kennedy attached a light silk ladder and motioned in pantomime for her to draw it up. It took her some time to fasten the ladder to one of the heavy pieces of furniture in the room. Swaying from side to side, but clinging with frantic desperation to the ladder while we did our best to steady it, she managed to reach the ground. She turned from the building with a shudder, and whispered:

"This terrible place! How can I ever thank you for getting me out of it?"

Kennedy did not pause long enough to say a word, but hurried her across to the final barrier, the wall.

Suddenly there was a shout of alarm from the front of the house under the columns. It was the night watchman, who had discovered us.

Instantly Kennedy seized a chair from a little summer-house.

"Quick, Walter," he cried, "over the wall with Mrs. Cranston, while I hold him! Then throw the ladder back on this side. I'll join you in a moment, as soon as you get her safely over."

A chair is only an indifferent club, if that is all one can think of using it for. Kennedy ran squarely at the watchman, holding it out straight before him. Only once did I cast a hasty glance back. There was the man pinned to the wall by the chair, with Kennedy at the other end of it and safely out of reach.

Mrs. Cranston and I managed to scramble over the wall, although she tore her dress on the pickets before we reached the other side. I hustled her into the car and made everything ready to start. It was only a couple of minutes after I threw the ladder back before Craig rejoined us.

"How did you get away from the watchman?" I demanded, breathlessly, as we shot away.

"I forced him back with the chair into the hall and slammed the door.

Then I jammed a wedge under it," he chuckled. "That will hold it better than any lock. Every push will jam it tighter."

Above the hubbub, inside now, we could hear a loud gong sounding insistently. All about were lights flashing up at the windows and moving through the pa.s.sageways. Shouts came from the back of the house as a door was finally opened there. But we were off now, with a good start.

I could imagine the frantic telephoning that was going on in the sanatorium. And I knew that the local police of Montrose and every other town about us were being informed of the escape. They were required by the law to render all possible a.s.sistance, and, as the country boasted several inst.i.tutions quite on a par with Belleclaire, an attempt at an escape was not an unusual occurrence.

The post-road by which we had come was therefore impossible, and Kennedy swung up into the country, in the hope of throwing off pursuit long enough to give us a better chance.

"Take the wheel, Walter," he muttered. "I'll tell you what turns to make. We must get to the State line of New York without being stopped.

We can beat almost any car. But that is not enough. A telephone message ahead may stop us, unless we can keep from being seen."

I took the wheel, and did not stop the car as Kennedy climbed over the seat. In the back of the car, where Mrs. Cranston was sitting, he hastily adjusted the peculiar apparatus.

"Sounds at night are very hard to locate," he explained. "Up this side road, Walter; there is some one coming ahead of us."

I turned and shot up the detour, stopping in the shadow of some trees, where we switched off every light and shut down the engine. Kennedy continued to watch the instrument before him.

"What is it?" I whispered.

"A phonometer," he replied. "It was invented to measure the intensity of sound. But it is much more valuable as an instrument that tells with precision from what direction a sound comes. It needs only a small dry battery and can be carried around easily. The sound enters the two horns of the phonometer, is focused at the neck, and strikes on a delicate diaphragm, behind which is a needle. The diaphragm vibrates and the needle moves. The louder the sound the greater the movement of this needle.

"At this end, where it looks as though I were sighting like a surveyor, I am gazing into a lens, with a tiny electric bulb close to my eye. The light of this bulb is reflected in a mirror which is moved by the moving needle. When the sound is loudest the two horns are at right angles to the direction whence it comes. So it is only necessary to twist the phonometer about on its pivot until the sound is received most loudly in the horns and the band of light is greatest. I know then that the horns are at right angles to the direction from which the sound proceeds, and that, as I lift my head, I am looking straight toward the source of the sound. I can tell its direction to a few degrees."

I looked through it myself to see how sound was visualized by light.

"Hush!" cautioned Kennedy.

Down on the main road we could see a car pa.s.s along slowly in the direction of Montrose, from which we had come. Without the phonometer to warn us, it must inevitably have met us and blocked our escape over the road ahead.

That danger pa.s.sed, on we sped. Five minutes, I calculated, and we should cross the State line to New York and safety.

We had been going along nicely when, "Bang!" came a loud report back of us.

"Confound it!" muttered Kennedy; "a blowout always when you least expect it."