was from Burke," he said as he hung up the receiver. "Confidential agents of his have been about. No one from the ship seems to have been down to see Forsythe, but Forsythe has had people over at the ship. Burke says someone is sending off great bunches of messages to Hayti—he thinks the powerful wireless apparatus of the Haytien is being used."
For a moment Kennedy stood in the center of the laboratory, thinking. Then he appeared to make up his mind to something.
"Has that taxicab gone?" he asked, opening a cabinet from which he took several packages.
I looked out of the window. The ambulance had gone back, but the driver of the car had evidently waited to call up his office for instructions. I beckoned to him, and together Kennedy and I placed the packages in the car.
Thus we were able quickly to get back again to the wharf where the Haytien was berthed. Instead of going aboard again, however, Kennedy stopped just outside, where he was not observed and got out of the car, dismissing it.
In the office of the steamship company, he sought one of the employés and handed him a card, explaining that we were aiding Burke in the case. The result of the parley was that Kennedy succeeded in getting to the roof of the covered pier on the opposite side from that where the ship lay.
There he set to work on a strange apparatus, wires from which ran up to a flag pole on which he was constructing what looked like a hastily improvised wireless aerial. That part arranged, Kennedy followed his wires down again and took them in by a window to a sort of lumber-room back of the office. Outside everyone was too busy to watch what we were doing there and Craig could work uninterrupted.
"What are you doing?" I asked. "Installing a wireless plant?"
"Not quite," he smiled quietly. "This is a home-made wireless photo-recording set. Of course, wireless aerials of amateurs don't hum any more since war has caused the strict censorship of all wireless. But there is no reason why one can't receive messages, even if they can't be sent by everybody.
"This is a fairly easy and inexpensive means by which automatic records can be taken. It involves no delicate instruments and the principal part of it can be made in a few hours from materials that I have in my laboratory. The basis is the capillary electrometer."
"Sounds very simple," I volunteered, trying not to be sarcastic.
"Well, here it is," he indicated, touching what looked like an ordinary soft glass tube of perhaps a quarter of an inch diameter, bent U-shaped, with one limb shorter than the other.
"It is filled nearly to the top of the shorter limb with chemically pure mercury," he went on. "On the top of it, I have poured a little twenty per cent sulphuric acid. Dipping into the acid is a small piece of capillary tube drawn out to a very fine point at the lower end."
He filled the little tube with mercury also. "The point of this," he observed, "is fine enough to prevent the mercury running through of its own weight—about as fine as a hair."
He dipped the point and held it in the sulphuric acid and blew through the capillary tube. When the mercury bubbled through the point in minute drops, he stopped blowing. It drew back for a short distance by capillary attraction and the acid followed it up.
"You can see that connections are made to the mercury in the arm and the tube by short pieces of platinum wire," he continued. "It isn't necessary to go into the theory of the instrument. But the most minute difference of potential between the two masses of mercury will cause the fine point at the junction of the liquids to move up and down.
"Connected to the aerial and the earth, with a crystal detector in series, it is only a matter of applying an ordinary photo-recording drum, and the machine is made."
He had been setting up a light-tight box, inside of which was a little electric lamp. Opposite was a drum covered with bromide paper. He started the clockwork going and after a few moments' careful observation, we went away, and left the thing, trusting that no one was the wiser.
Nothing further occurred that day, except for frequent reports from Burke, who told us how his men were getting on in their shadowing of Forsythe & Co. Apparently, the death of Leon had put a stop to revolutionary plots, or at least had caused the plotters to change their methods radically.
The time was shortening, too, during which Burke could keep the passengers of the Haytien under such close surveillance, and it was finally decided that on the next morning they should be released, while all those suspected were to be shadowed separately by Secret Service agents, in the hope that once free they would commit some overt act that might lead to a clew.
Chapter XXXIII
The Respiration Calorimeter
It was early the next morning, about half an hour after the time set for the release of the passengers, that our laboratory door was flung open and Collette Aux Cayes rushed in, wildly excited.
"What's the matter?" asked Kennedy anxiously.
"Someone has been trying to keep me on the boat," she panted. "And all the way over here a man has been following me."
Kennedy looked at her a minute calmly. We could understand why she might have been shadowed, though it must have been a bungling job of Burke's operative. But who could have wanted her kept on the boat?
"I don't know," she replied, in answer to Kennedy's question. "But somehow I was the only one not told that we could go. And when I did go, one of the Secret Service men stopped me."
"Are you sure it was a Secret Service man?"
"He said he was."
"Yes, but if he had been, he would not have done that, nor let you get away, if he had. Can't you imagine anyone who might want you detained longer?"
She looked at us, half frightened. "N—not unless it is that man—or the woman with him," she replied, clasping her hands.
"You mean Castine?"
"Yes," she replied, avoiding the use of his name. "Ever since you had the body removed, he has been in great fear. I have heard him ask fifty times, 'Where have they taken him?' and 'Is he to be embalmed?'"
"That's strange," remarked Kennedy. "Why that anxiety from him? I remember that it was he who wanted the body left alone. Is it for fear that we might discover something which might be covered up?"
Kennedy disappeared into the anteroom and I heard him making a great fuss as he regulated the various pieces of machinery that surrounded the little chamber.
Some minutes later, he emerged.
"Meet us here in an hour," he directed Collette, "with your guardian."
Quickly Craig telephoned for a tank of oxygen to be sent over to the laboratory, then got Burke on the wire and asked him to meet us down at the dock.
We arrived first and Craig hurried into the lumber-room, where fortunately he found everything undisturbed. He tore off the strip of paper from the drum and held it up. On it was a series of marks, which looked like dots and dashes, of a peculiar kind, along a sort of base line.
