"Men from the surface," she said, "you, Frank Rowley, and you, Arnold Thompson, are about to witness the powers of that hemisphere of metal you were pleased to term 'Silver Dome.' As you rightly surmised, the dome is of silver--mostly. There are small percentages of platinum, iridium, and other elements, but it is more than nine-tenths pure silver. To you of the surface the alloy is highly valuable for its intrinsic worth by your own standards, but to us the value of the dome lies in its function in revealing to us the past and present events of our universe. The dome is the 'eye' of a complicated apparatus which enables us to see and hear any desired happening on the surface of the earth, beneath its surface, or on the many inhabited planets of the heavens. This is accomplished by means of extremely complex vibrations radiated from the hemisphere, these vibrations penetrating earth, metals, buildings, space itself, and returning to our viewing and sound reproducing spheres to reveal the desired past or present occurrences at the point at which the rays of vibrations are directed. * * * * * "In order to view the past on our own planet, the rays, which travel at the speed of light, are sent out in a huge circle through space, returning to earth after having spent the requisite number of years in transit. Instantaneous effect is secured by a connecting beam that ties together the ends of the enormous arc. This, of course, is beyond your comprehension, since the Ninth Dimension is involved. When it is desired that events of the present be observed, the rays are projected direct. The future can not be viewed, since, in order to accomplish this, it would be necessary that the rays travel at a speed greater than that of light, which is manifestly impossible." "Great guns!" gasped Frank. "This crystal sphere then, is capable of bringing to our eyes and ears the happenings of centuries past?" "It is, my dear Frank," said Phaestra, "and I would that I were able to describe the process more clearly." She smiled, and in the unearthly light of the sphere she appeared more beautiful than before, if such a thing were possible. On the pedestal which supported the sphere there was a glittering array of dials and levers. Several of these controls were now adjusted by Phaestra, the delicate motions of her tapered fingers being watched by the visitors with intense admiration. There came a change in the note of the sphere, a steadying of the flickerings within. "Behold!" exclaimed Phaestra. * * * * *