the pass where the rock was located. A draft of air up the hill made breathing a little easier as the trio descended into the pass, and in a surprizingly short time they had arrived at a long, odd-looking structure built of concrete, hardwood and sundry other materials, which lay alongside a huge, grayish-black rock. Of the size of the building they could not get any clear idea until they entered.
"Welcome to our castle," announced Walter, as the door was opened by a tame enough yellow negro. "Museum, laboratory and living quarters all in one, and the coolest place in Africa north of the equator."
Tiny electric lights, well placed, lighted the structure at will, and fans which brought the air supply through underground passages made the place quite comfortable.
They dined in the largest room, one side of which was formed by the surface of the rock, a common-looking formation to the casual glance.
By the time the meal was finished the brief African twilight was gone and the outer world was in blackness. Walter arose from the table and went back to the outer wall, where a number of switches controlled the electric current from his power plant.
"And now if you folks will excuse the lights," he said, "we'll have a look at the light of another century—nobody knows just which one."
The room was left in total blackness for a time, but as the eyes became accustomed to this, a curious sight began to dawn where the gray rock had been. Straight through the rock the little audience began to see—across the little pass, up the other side, even to a distant patch of sky visible above the profile of the hill at one place. This scene differed from that outside at the moment in only one particular, that many of the rocks were higher and sharper in the magical view, showing what centuries of wind and sand had done toward wearing them down. It was all very faint, and could be made out with difficulty.
Then, at the click of another switch, the scene grew clearer and as bright as day. The rock did not exist—they saw through it as through a piece of lens glass. A vagrant wind stirred a cloud of dust and sand to action.
"A dull day in the pass," commented Walter, "but it wasn't always that way. I'm going to speed it up until we strike something."
The scene whirled on, varying from dazzling light to blackness, representing days and nights, in periods of a minute or two, until Walter's quick eye caught a flash of red. Instantly he snapped off the switch and turned the current back to show the movement at its natural speed. A blazing camp-fire illuminated the rocks, and about it were gathered many strange, dark figures; hairy, heavy-jowled creatures that jostled one another roughly and showed grimaces of laughter when one of their number stumbled barefooted upon a red ember.
But why describe it further here? Why go into details regarding scenes that have been reproduced by camera and newspaper in every country on the globe?
Walter Frey was too intent on his experiment to note the effect of this phenomenon on his visitors until, after half an hour spent in drawing out the marvelous picture from the rock, he stopped the electric current and lighted up the cavernlike interior again. Then, after feasting his eyes on Isabel's glorified countenance, he turned to observe Henry Kopp's reactions.
His first impression was that Henry was suffering from a complex of some kind—probably an inferiority complex. He had slumped down in his chair somewhat, and his face had lost its aggressive, cocksure expression for the moment. Henry's eyes were still riveted on the dead-looking
