A heated argument followed until finally a corporal of the guards was called and led off the tramp toward the headquarters.

It was only a few minutes before Woodward was convinced of the ident.i.ty of the tramp with his friend, Professor Arnold. At the head of a squad of cavalry, Woodward and the tramp dashed off.

Already on the qui vive, Elaine heard the sound of hoof-beats long before the rest of us crowded around her. For the moment we all stood ready to repel an attack from any quarter.

But it was not meant for us. It was Woodward at the head of a score or so of cavalrymen. With him rode a tramp on a horse which was strangely familiar to me.

"Oh," cried Elaine, "there's the man who saved me!"

As they pa.s.sed, the tramp paused a moment and looked at us sharply.

Although he carefully avoided Elaine's eyes, I fancied that only when he saw that she was safe was he satisfied to gallop off and rejoin the cavalry.

Around the old hotel, in every direction, Del Mar's men were searching for the tramp and Elaine, while in the hotel another search was in progress.

"Have you discovered anything?" asked Del Mar, entering.

"No, sir," they reported.

"Confound it!" swore Del Mar, going up-stairs again.

Here also were men searching. "Find anything?" he asked briefly.

"No luck," returned one.

Del Mar went on up to the top floor and out through the open scuttle to the roof. "That's how he got away, all right," he muttered to himself, then looking up he exclaimed under his breath, as his eye caught something far off, "The deuce--what's that?"

Leaning down to the scuttle, he called, "Jenkins--my field-gla.s.ses--quick!"

One of his men handed them to him and he adjusted them, gazing off intently. There he could see what looked like a squad of cavalry galloping along headed by an officer and a rough looking individual.

"Come--we must get ready for an attack!" he shouted diving down the scuttle again.

In the laboratory dining-room, his men, recalled, hastily took his orders. Each of them seized one of the huge black rubber newly completed gas bombs and ran out, making for a grove near-by.

Quickly as Del Mar had acted, it was not done so fast but that the troop of cavalry as they pulled up on the top of a hill and followed the directing finger of the tramp could see men running to the cover of the grove.

"Forward!" shouted Woodward.

As if all were one machine, the men and horses shot ahead, until they came to the grove about the old hotel. There they dismounted and spread out in a semi-circular order, advancing on the grove. As they did so, shots rang out from behind the trees. Del Mar's men, from the shelter were firing at them. But it seemed hopeless for the fugitives.

"Ready!" ordered Del Mar as the cavalrymen advanced, relentless.

Each of his men picked up one of the big black gas bombs and held it high up over his head.

"Come on!" urged Woodward.

His men broke into a charge on the grove.

"Throw them!" ordered Del Mar.

As far as he could hurl it, each of the men sent one of the black globes hurtling through the air. They fell almost simultaneously, a long line of them, each breaking into a thousand bits. Instantly dense, greenish-yellow fumes seemed to pour forth, enveloping everything. The wind which Del Mar had carefully noted when he chose the position in the grove, was blowing from his men toward the only position from which an attack could be made successfully.

Against Woodward's men as they charged, it seemed as if a tremendous, slow-moving wall of vapor were advancing from the trees. It was only a moment before it completely wrapped them in its stifling, choking, suffocating embrace. Some fell, overcome. Others tried to run, clutching frantically at their throats and rubbing their eyes.

"Get back--quick--till it rolls over," choked Woodward.

Those who were able to do so, picked up their stupefied comrades and retreated, as best they could, stumbling blindly back from the fearful death cloud of chlorine.

Meantime, under cover of this weird defence, Del Mar and his men, their own faces covered and unrecognizable in their breathing masks and goggles, dashed to one side, with a shout and disappeared walking and running behind and even through the safety of their impregnable gas barrier.

More slowly we of the hunt had followed Woodward's cavalry until, some distance off, we stood, witnessing and wondering at the attack. To our utter amazement we saw them carrying off their wounded and stupefied men. We hurried forward and gathered about, offering whatever a.s.sistance we could to resuscitate them.

As Elaine and I helped, we saw the unkempt figure of the tramp borne in and laid down. He was not completely overcome, having had presence of mind to tie a handkerchief over his nose and mouth.

Elaine hurried toward him with an exclamation of sympathy. Just recovering full consciousness, he heard her.

With the greatest difficulty, he seemed to summon some reserve force not yet used. He struggled to his feet and staggered off, as though he would escape us.

"What a strange old codger," mused Elaine, looking from me at the retreating figure. "He saved my life--yet he won't even let me thank him--or help him!"

CHAPTER XIII

THE SEARCHLIGHT GUN

"I don't understand it," remarked Elaine one day as, with Aunt Josephine and myself, she was discussing the strange events that had occurred since the disappearance of Kennedy, "but, somehow, it is as if a strange Providence seems to be watching over us."

"Nor do I," I agreed. "It does seem that, although we do not see it, a mysterious power for good is about us. It's uncanny."

"A package for you, Miss Dodge," announced Marie, coming in with a small parcel which had been delivered by a messenger who did not wait for an answer.

Elaine took it, looked at it, turned it over, and then looked at the written address again.

"It's not the handwriting of any one which I recognize," she mused.

"Now, I suppose I ought to be suspicious of it Yet, I'm going to open it."

She did so. Inside, the paper wrapping covered a pasteboard box. She opened that. There lay a revolver, which she picked up and turned over.

It was a curious looking weapon.

"I never knew so much about firearms as I have learned in the past few weeks," remarked Elaine. "But what do you suppose this is--and who sent it to me--and why?"

She held the gun up. From the barrel stuck out a little rolled-up piece of paper. "See," she cried, reading and handing the paper to me, "there it is again--that mysterious power."

Aunt Josephine and I read the note: