Almost before we knew it the speed demon had disappeared beyond the
circle of the flares.
“Suspiciously near the _Sybarite_,” remarked Kennedy, under his breath,
watching the scout cruiser to the last moment as she ran away.
I wondered whether he meant that the swift little motor-boat might
have some connection with Shelby Maddox and his new activities, but I
said nothing, for Kennedy’s attention was riveted on the wake left by
the boat. I looked, too, and could have sworn that there was something
moving in the opposite direction to that taken by the boat. What could
it be?
On the end of the dock was an incandescent lamp. Craig unscrewed the
bulb and inserted another connection in the bulb socket, an insulated
cable that led down to the apparatus on the float over which his
assistant was still working.
By this time quite a crowd had collected on the dock, and on the float,
watching us.
“Burke,” ordered Kennedy, “will you and Jameson make the people stand
back? We can’t do anything with so many around.”
As we pressed the new-comers back I saw that among them was Paquita.
Though I looked, I could not discover Sanchez, but thought nothing of
it, for there were so many about that it would have been hard to find
any particular person.
“If you will please stand back,” I implored, trying to keep the
curious from almost swamping the float, “you will all be able to
see what is going on just as well and, besides, it will be a great
deal safer――providing there is an explosion,” I added as a happy
afterthought, although I had almost as vague an idea what Kennedy was
up to as any of them.
The words had the effect I intended. The crowd gave way, not only
willing, but almost in panic.
As they pressed back, however, Paquita pressed forward until she was
standing beside me.
“Is――Mr. Maddox――out there?” she asked, pointing out at the _Sybarite_
anxiously.
“Why?” I demanded, hoping in her anxiety to catch her off guard.
She shot a quick glance at me. There was no denying that the woman was
clever and quick of perception.
“Oh, I just wondered,” she murmured. “I wanted to see him, so
much――that is all. And it’s very urgent.”
She glanced about, as though hoping to discover some means of
communicating with the yacht, even of getting out to it. But there did
not seem to be any offered.
I determined to watch her, and for that reason did not insist that she
get back as far as the rest of the crowd. All the time I saw that she
was looking constantly out at the _Sybarite_. Did she know something
about Shelby Maddox that we did not know? I wondered if, indeed, there
might be some valid reason why she should get out there. What did she
suspect?
Again she came forward, inquiring whether there was not some way of
communicating with the _Sybarite_, and again, when I tried to question
her, she refused to give me any satisfaction. However, I could not help
noticing that in spite of the cold manner in which Shelby had treated
her, she seemed now to be actuated more by the most intense fear for
him than by any malice against him.
What it meant I had the greatest curiosity to know, especially when I
noticed that Paquita was glancing nervously about as though in great
fear that some one might be present and see her. Nor did she seem to
be deterred from showing her feelings by the fact that she knew that I,
Kennedy’s closest friend, was watching and would undoubtedly report to
him. It was as though she had abandoned discretion and cast fear to the
winds.
As the minutes passed and nothing happened, Paquita became a trifle
calmer and managed to take refuge in the crowd.
I took the opportunity again to run my eye over them. Nowhere in
the crowd could I discover Winifred, or, in fact, any of the Maddox
family. They seemed to be studiously avoiding appearance in public just
now, and I could not blame them, for in a summer colony like that at
Westport facts never troubled gossipers.
“What do you suppose Kennedy is afraid of?” whispered Hastings in my
ear, nervously. “Your friend is positively uncanny, and I can almost
feel that he fears something.”
“I’m sure I don’t know,” I confessed, “but I’ve seen enough of him
to be sure that no one is going to catch him napping. Here’s Riley.
Perhaps he has some news.”
The Secret Service operative had shouldered his way through the throng,
looking for Burke, who was right behind me.
“What’s the matter,” demanded his chief.
“There’s another message, by telephone from the Seaville Station,”
Riley reported. “They say they are having the same trouble again――only
more of it.”
“That operator, Steel, came back again,” considered Burke. “Where is
he?”
“As soon as I got the message, I hunted him up and took the liberty of
sending him up to Mr. Kennedy’s room to look at that arrangement there.
I couldn’t make anything out of it myself, I knew, and I thought that
he could.”
“Did he?” inquired Burke.
“Yes. Of course he hadn’t seen it work before. But I told him as nearly
as I could what you had told me, and it didn’t take him very long to
catch on to the thing. After that he said that what was being recorded
now must be just the same as it had been before when Mr. Kennedy was
there――not messages, but just impulses.”
“Where is he――down here?”
“No, I left him up there. I thought it might be best to have some one
there. Did you want to speak to him? There’s a telephone down here in
the boat-house up to the switchboard at the Lodge.”
Riley jerked his thumb back over his shoulder at a little shelter built
on the end of the dock.
“N-no,” considered Burke. “I wouldn’t know what to tell him.”
“But I think you ought to tell Kennedy that,” I interrupted. “He might
know what to do.”
Together Riley and I walked across the float to where Craig was at
work, and briefly I told him what had happened.
He looked grave, but did not pause in his adjustment of the machine,
whatever it was.
“That’s all right,” he approved. “Yes, get the operator on the wire.
Tell him to stay up there. And――yes――tell him to detach that phonograph
recording device and go back to straight wireless. He might try to wake
up the operator on the _Sybarite_, if he can. I guess he must know the
call. Have him do that and then have that telephone girl keep the line
clear and connected from the boat-house up to my room. I want to keep
in touch with Steel.”
Riley and I pushed through the crowd and finally managed to deliver
Kennedy’s message, in spite of the excitement at the Lodge, which had
extended by this time to the switchboard operator. I left Riley in the
boat-house to hold the wire up to our room, and rejoined Burke and
Hastings on the float.
Kennedy had been working with redoubled energy, now that the light
bombs had gone out after serving their purpose. We stood apart now as
he made a final inspection of the apparatus which he and his assistant
had installed.
Finally Craig pressed down a key which seemed to close a circuit
including the connection in the electric-light socket and the
arrangement that had been let over the edge of the float. Standing
where we were we could feel a sort of dull metallic vibration under our
feet, as it were.
“What are you doing?” inquired Hastings, looking curiously at a
headgear which Kennedy had over his ears.
“It works!” exclaimed Craig, more to Watkins than to us.
“What does?” persisted Hastings.
“This Fessenden oscillator,” he cried, apparently for the first time
recognizing that Hastings had been addressing him.
“What is it?” we asked crowding about. “What does it do?”
“It’s a system for the employment of sound for submarine signals,” he
explained, hurriedly. “I am using it to detect moving objects in the
water――under the water, perhaps. It’s really a submarine ear.”
In our excitement we could only watch him in wonder.
“People don’t realize the great advance that has been made in the
use of water instead of air as a medium for transmitting sounds,” he
continued, after a pause, during which he seemed to be listening,
observing a stop watch, and figuring rapidly on a piece of paper, all
at once. “I can’t stop to explain this apparatus, but, roughly, it is
composed of a ring magnet, a copper tube which lies in an air gap of a
magnetic field, and a stationary central armature. The magnetic field
is much stronger than that in an ordinary dynamo of this size.”
Again he listened, as he pressed the key, and we felt the peculiar
vibration, while he figured on the paper.
“The copper tube,” he resumed mechanically to us, though his real
attention was on something else, “has an alternating current induced in
it. It is attached to solid disks of steel, which in turn are attached
to a steel diaphragm an inch thick. Surrounding the oscillator is a
large watertight drum.”
“Then it makes use of sound-waves in the water?” queried Hastings,
almost incredulously.
“Exactly,” returned Craig. “I use the same instrument for sending and
receiving――only I’m not doing any real sending. You see, like the
ordinary electric motor, it is capable of acting as a generator, too
and a very efficient one. All I have to do is to throw a switch in one
direction when I want to telegraph or telephone under water, and in the
other direction when I want to listen.”
“Talking through water!” exclaimed Burke, awestruck by the very idea,
as though it were scarcely believable.
“That’s not exactly what I’m doing now,” returned Kennedy, indulgently,
“although I could do it if there was any one around this part of the
country equipped to receive and reply. I rather suspect, though, that
whoever it is is not only not equipped, but wouldn’t want to reply,
anyhow.”
“Then what are you doing?” asked Burke, rather mystified.
“Well, you see I can send out signals and listen for their
reflection――really the echo under water. More than that, I can get the
sounds direct from any source that is making them. If there was a big
steamer out there I could hear her engines and propellers, even if I
couldn’t see her around the point. Light travels in straight lines, but
you can get sounds around a corner, as it were.”
“Oh,” I exclaimed, “I think I see. Even if that little scout cruiser
did disappear around the point, you can still hear her through the
water. Is that it?”
“Partly,” nodded Kennedy. “You know, sound travels through water at a
velocity of about four thousand feet a second. For instance, I find
I can get an echo from somewhere practically instantaneously. That’s
the bottom of the bay――here. Another echo comes back to me in about a
twentieth of a second. That, I take it, is reflected from the sea wall
on the shore, back of us, at high tide. It must be roughly a hundred
feet――you see, that corresponds. It is a matter of calculation.”
“Is that all?” I prompted, as he paused again.
“No, I’ve located the echo from the _Sybarite_ and some others. But,”
he added slowly, “there’s one I can’t account for. There’s a sound
that is coming to me direct from somewhere. I can’t just place it, for
there isn’t a moving craft visible and it doesn’t give the same note
as that little cruiser. It’s sharper. Just now I tried to send out my
own impulses in the hope of getting an echo from it, and I succeeded.
The echo comes back to me in something more than five seconds. You see,
that would make twenty thousand-odd feet. Half of that would be nearly
two miles, and that roughly corresponds with the position where we
saw the scout cruiser at first, before it fled. There’s something out
there.”
“Then I was right,” I exclaimed excitedly. “I thought I saw something
in the wake of the cruiser.”
Kennedy shook his head gravely. “I’m afraid you were,” he muttered.
“There’s something there, all right. That wireless operator is up in
our room and you have a wire from the boathouse to him?”
“Yes,” I returned. “Riley’s holding it open.”
Anxiously Kennedy listened again in silence, as though to verify some
growing suspicion. What was it he heard?
Quickly he pulled the headgear off and before I knew it had clapped it
on my own head.
“Tell me what it sounds like,” he asked, tensely.
I listened eagerly, though I was no electrical or mechanical engineer,
and such things were usually to me a sealed book. Still, I was able to
describe a peculiar metallic throbbing.
“Record the time for the echo from it,” ordered Kennedy, thrusting the
stop watch into my hands. “Press it the instant you hear the return
sound after I push down the key. I want to be sure of it and eliminate
my own personal equation from the calculation. Are you ready?”
I nodded and an instant later, as he noted the time, I heard through
the oscillator the peculiar vibration I had felt when the key was
depressed. On the _qui vive_ I waited for the return echo. Sure
enough, there it was and I mechanically registered it on the watch.
“Five and thirty-hundredths seconds,” muttered Kennedy. “I had five and
thirty-five hundredths. It’s coming nearer――you hear the sound direct
again?”