He pointed to the huge oaken door and Frank saw that it was ajar. The snow on the porch was not deep and they saw that footprints led from the open door to a corner of the porch. At that point the snow on the railing was disturbed, as if a hurrying man had clung to it a moment before jumping over and into the drifts below. But the tracks led no further, for the drifting snow had covered all excepting a hollow where some body had landed.

"Thomas!" exclaimed Frank. "And he was in a hustle, by the looks of the tracks. Bet he was frightened while at the telephone and beat it."

They entered the house and closed the door behind them. It was growing quite dark and Frank searched for the light switch. This was near the door, and, at pressure on the upper b.u.t.ton, the s.p.a.cious old hall with its open staircase was revealed dimly by the single remaining bulb in a cl.u.s.ter set in the center of the high ceiling. The hall was unfurnished, excepting for a telephone table and chair, the chair having fallen to the floor and the receiver of the telephone dangling from the edge of the table by its cord.

"You must have heard the chair fall," commented Tommy, "and it sure does look as if Thomas left in a hurry. Wonder what it was that frightened him?"

The house was eerily silent and the words echoed awesomely through the adjoining rooms which connected with the hall through large open doorways.

"Spooky place, isn't it?" returned Frank.

And then they were both startled into immobility by a rumble that seemed to shake the foundations of the house. Heavier and heavier became this vibration, as if some large machine was coming up to speed. Louder and louder grew the rumble until it seemed that the rickety old house must be shaken down about their ears. Then there came a whistling scream from the depths of the earth--from far underground it seemed to be--and this mounted in pitch until their eardrums tingled. Then abruptly the sounds ceased, the vibration stopped, and once more there was the eery silence.

Rather white-faced, Tommy gazed at Frank.

"No wonder old Thomas beat it!" he said. "What on earth do you suppose that is?"

"Search me," replied Frank. "But whatever it is, I'll bet it has something to do with Leland's strange actions. And we're going to find out."

He had with him the large flashlamp from the car, and, by its light, the two made their way from room to room searching for the iron-bound door mentioned by Thomas.

They found all rooms on the first and second floors dusty and unused with the exception of two bedrooms, the kitchen and pantry, and the library. It was a gloomy and spooky old house. Floor boards creaked startlingly and unexpectedly and the sound of their footsteps echoed dismally.

"Where in time is that laboratory of Leland's?" exclaimed Frank, his ruddy features showing impatient annoyance, exaggerated to an appearance of ferocity by the light of the flashlamp.

"How about the cellar?" suggested Tommy.

"Probably where it is," agreed Frank, "but I don't relish this job so much. I'd hate to find Leland stiff down there, if that's where he is."

"Me, too," said Tommy. "But we're here now, so let's finish the job and get back home. It's cold here, too."

"You said it. No steam in the pipes at all. He must have let the fire go out in his furnace, and that's probably in the cellar too--usually is."

While talking, Frank had opened each of the four doors that opened from the kitchen, and the fourth revealed a stairway that led into the blackness beneath. With the beam of his torch directed at the steps, he proceeded to descend, and Tommy followed carefully. There was no light b.u.t.ton at the head of the stairs, where it would have been placed in a more modern house, and it was not until they had reached the furnace room that they located a light fixture with a pull cord.

An ordinary cellar, with furnace, coal bin, and a conglomeration of dust-covered trunks and discarded furniture, was revealed. And, at its far end, was the iron-bound door.

The door was locked and could not be shaken by the combined efforts of the two men.

"Have to have a battering ram," grunted Frank, casting about for a suitable implement.

"Here you are," called Tommy, after a moment's search. "Just the thing we are looking for."

He had come upon a pile of logs, and one of these, evidently a section of an old telephone pole, was of some ten or twelve inches diameter and about fifteen feet long. Frank pounced upon it eagerly, and, supporting most of the weight himself, led the attack on the heavy oak door with the iron bands.

No sound from within greeted the thunderous poundings. Clearly, if Leland was behind that door, he was either dead or unconscious.

Finally the double lock gave way and Tommy and Frank were precipitated headlong into the brightly lighted room beyond. Recovering their balance, they took stock of their surroundings and were amazed at what they saw--a huge laboratory, fitted out with every modern appliance that money could buy. A completely equipped machine shop there was; bench after bench covered with the familiar paraphernalia of the chemical and physical laboratory; huge retorts and stills; complicated electrical equipments; dozens of cabinets holding crucibles, flasks, bottles, gla.s.s tubing, and what not.

"Good Lord!" gasped Tommy. "Here's a laboratory to more than match our own. Why, Leland's got a fortune invested here!"

"I should say so. And a lot of stuff that our company does not even have. Some of it I don't know even the use of. But where is Leland?"

There was no sign of the man they had come to help. He was not in the laboratory, though the door had been locked from within and the lights left burning throughout.

With painstaking care they searched every nook and cranny of the large single room and were about to give up in despair when Tommy happened to observe an ivory b.u.t.ton set into the wall at the only point in the room where there were no machines or benches at hand. Experimentally he pressed the b.u.t.ton, and, at the answering rumble from under his feet, jumped back in alarm. Slowly there opened in the paneled oak wall a rectangular door, a door of large enough size to admit a man.

From the recess beyond there came a breath of air, foul with the musty odor of decayed vegetation, dank as the air of a tomb.

"Ah-h-h!" breathed Frank. "So that is where Ed Leland is hiding! The secret retreat of the gloomy scientist!"

He spoke half jestingly, yet when he squeezed his stalwart bulk through the opening and flashed the beam of his light into the darkness of a narrow pa.s.sage ahead he was a.s.sailed with vague forebodings. Tommy followed close behind and spoke not a word.

The pa.s.sage floor was thick with dust, but the marks of many footsteps going and returning gave mute evidence of the frequency of Leland's visits. The air was heavy and oppressive and the temperature and humidity increased as they progressed along the winding length of the rock-walled pa.s.sageway. The floor sloped, ever downward and, in spots, was slippery with slimy seepage. It seemed that they turned back on their course on several occasions but were descending deeper and deeper into the heart of the mountain. Then, abruptly, the pa.s.sage ended at the mouth of a shaft, which dropped vertically from almost beneath their feet.

"Whew!" exclaimed Frank. "Another step and I'd have dropped into it.

That's probably what happened to Leland."

He knelt at the rim of the circular opening and looked into the depths of the pit, Tommy following suit. The feeble ray of the flashlight was lost in the blackness below.

"Say, Frank," whispered Tommy, "turn off the flash. I think I saw a light down there."

And, with the snapping of the catch, there came darkness. But, miles below them, it seemed, there was a tiny pin-point of brilliance--an eery green light that was like a wavering phosph.o.r.escence of will-o'-the-wisp. For a moment it shone and was gone. Then came the dreadful vibration they had experienced in the hall of the house--the whistling scream that grew louder and louder until it seemed they must be deafened. The penetrating wail rose from the depths of the pit, and the vibration was all around them, in the damp rock floor on which they knelt, and in the very air of the cavern. Hastily Frank snapped on the light of his flash.

"Oh boy!" he whispered. "Leland is certainly up to something down there and no mistake! How're we going to get down?"

"Get down?" asked Tommy. "You don't want to go down there, do you?"

"Sure thing. We're this far now and, by George, we're going to find out all there is to learn."

"How deep do you suppose it is?"

"Pretty deep, Tommy. But we can get an idea by dropping a stone and counting the seconds until it strikes."

He played the light of the flash over the floor and soon located a smooth round stone of the size of a baseball. This he tossed over the rim of the pit and awaited results.