In the office of the Works at Sardis, side by side at the table on which stood the telegraph instrument, Margaret Raleigh and Roland Clewe, receiving the daily reports from the Dipsey, had found themselves in such sympathy and harmony with the party they had sent out on this expedition that they too, in fancy, had slowly groped their way under the grim overhanging ice out into the open polar sea. They too had stood on the deck of the vessel which had risen like a spectre out of the waters, and in the cold, clear atmosphere had gazed about them at this hitherto unknown part of the world. They had thrilled with enthusiastic excitement when the ring on the deck of the Dipsey was placed over the actual location of the pole; they had been filled with anger when they heard of the conduct of Rovinski; and their souls had swelled with a noble love of country and pride in their own achievements when they heard that they, by their representative, had made the north pole a part of their native land. They had listened, scarcely breathing, to the stirring account of the anchoring of the great buoy to one end of the earth's axis, and they had exclaimed in amazement at the announcement that in the lonely waters of the pole whales were still to be found, when they were totally unknown in every other portion of the earth.

But now the stirring events in the arctic regions which had so held and enthralled them day by day had, after a time, ceased. Mr. Gibbs was engaged in making experiments, observations, and explorations, the result of which he would embody in carefully prepared reports, and Sammy's daily message promised to be rather monotonous. Roland Clewe felt the great importance of a thorough exploration and examination of the polar sea. The vessel he had sent out had reached this hitherto inaccessible region, but it was not at all certain that another voyage, even of the same kind, would be successful. Consequently he advised those in charge of the expedition not to attempt to return until the results of their work were as complete as possible. Should the arctic night overtake them before they left the polar sea, this would not interfere with their return in the same manner in which they had gone north, for in a submarine voyage artificial light would be necessary at any season. So, for a tune, Roland and Margaret withdrew in a great measure their thoughts from the vicinity of the pole, and devoted themselves to their work at home.

When Roland Clewe had penetrated with his Artesian ray as deeply into the earth beneath him as the photic power of his instrument would admit, he had applied all the available force of his establishment—the men working in relays day and night—to the manufacture of the instruments which should give increased power to the penetrating light, which he hoped would make visible to him the interior structure of the earth, up to this time as unknown to man as had been the regions of the poles.

Roland had devoted a great deal of time to the arrangement of a system of reflectors, by which he hoped to make it possible to look down into the cylinder of light produced by the Artesian ray without projecting any portion of the body of the observer into the ray. This had been done principally to provide against the possibility of a shock to Margaret, such as he received when he beheld a man with the upper part of his body totally invisible, and a section of the other portion laid bare to the eye of a person standing in front of it. But his success had not been satisfactory. It was quite different to look directly down into that magical perforation at his feet, instead of studying the reflection of the same, indistinctly and uncertainly revealed by a system of mirrors.

Consequently the plan of reflectors was discarded, and Roland determined that the right thing to do was to take Margaret into his confidence and explain to her why he and she should not stand together and look down the course of the Artesian ray. She scolded him for not telling her all this before, and a permanent screen was erected around the spot on which the ray was intended to work, formed of Venetian blinds with fixed slats, so that the person inside could readily talk and consult with others outside without being seen by them.

As might well be supposed, this work with the “photic borer,” as Clewe now called his instrument, was of absorbing interest. For a day or two after it was again put into operation Margaret and Roland could scarcely tear themselves away from it long enough for necessary sleep and meals, and several persons connected with the Works were frequently permitted to witness its wonderful operations.

Down, down descended that cylinder of light, until it had passed through all the known geological strata in that part of New Jersey, and had reached subterranean depths known to Clewe only by comparison and theory.

The apparent excavation had extended itself down so far that the disk at the bottom, although so brightly illuminated, was no longer clearly visible to the naked eye, and was rapidly decreasing in size on account of the perspective. But the telescopes which Clewe had provided easily overcame this difficulty. He was sure that it would be impossible for his light to penetrate to a depth which could not be made clearly visible by his telescopes.

It was a wonderful and weird sensation which came over those who stood, glass in hand, and gazed down the track of the Artesian ray. Far, far below them they saw that illuminated disk which revealed the character of the stratum which the light had reached. And yet they could not see the telescope which they held in their hands; they could not see their hands; they knew that their heads and shoulders were invisible. All observers except Clewe kept well back from the edge of the frightful hole of light down which they peered; and once, when the weight of the telescope which she held had caused Margaret to make an involuntary step forward, she gave a fearful scream, for she was sure she was going to fall into the bowels of the earth. Clewe, who stood always near by, with his hand upon the lever which controlled the ray, instantly shut off the light; and although Margaret was thus convinced that she stood upon commonplace ground, she came from within the screen, and did not for some time recover from the nervous shock occasioned by this accident of the imagination.

Clewe himself took great pleasure in making experiments connected with the relation of the observer to the action of the Artesian ray. For instance, he found that when standing and gazing down into the great photic perforation below him, he could see into it quite as well when he shut his eyes as when they were open; the light passing through his head made his eyelids invisible. He stood in the very centre of the circle of light and looked down through himself.

That this application of light which he had discovered would be of the greatest possible service in surgery, Roland Clewe well knew. By totally eliminating from view any portion of the human body so as to expose a section of said body which it was desirable to examine, the interior structure of a patient could be studied as easily as the exterior, and a surgeon would be able to dissect a living being as easily as if the subject were a corpse. But Clewe did not now wish to make public the extraordinary adaptations of his discovery to the uses of the medical man and the surgeon. He was intent upon discovering, as far as was possible, the internal structure of the earth on which he dwelt, and he did not wish to interfere at present with this great and absorbing object by distracting his mind with any other application of his Artesian ray.

It is not intended to describe in detail the various stages of the progress of the Artesian ray into the subterranean regions. Sometimes it revealed strata colored red, yellow, or green by the presence of iron ore; sometimes it showed for a short distance a glittering disk, produced by the action of the light upon a deep-sunken reservoir of water; then it passed on, hour by hour, down, down into the eternal rocks.

When the Artesian ray had begun to work its way through the rocks, Margaret became less interested in observing its progress. Nothing new presented itself; it was one continual stony disk which she saw when she looked down into the shaft of light beneath her. Observation was becoming more and more difficult even to Roland Clewe, and at last he was obliged to set up a large telescope on a stand, and mount a ladder in order to use it.

Day after day the Artesian ray went downward, always revealing rock, rock, rock. The appliances for increased electric energy were working well, and Clewe was entirely satisfied with the operation of his photic borer.

One morning he came hurriedly to Margaret at her house, and announced with glistening eyes that his ray had now gone to a greater degree into the earth than man had ever yet reached.

“What have you found?” she asked, excitedly. “Rock, rock, rock,” he answered. “This little State of ours rests upon a firm foundation.”

Although Roland Clewe found his observations rather monotonous work, he was regular and constant at his post, and gave little opportunity to his steadily progressing cylinder of light to reach and pass unseen anything which might be of interest.

It was nearly a week after he had announced to Margaret that he had seen deeper into the earth than any man before him that he mounted his ladder to take his final observation for the night. When he looked through his telescope his eye was dazzled by a light which obliged him suddenly to close it and lift his head. At first he thought that he had reached the fabulous region of eternal fire, but this he knew to be absurd; and, besides, the light was not that of fire or heated substances. It was pale, colorless; and although dazzling at first, he found, when very cautiously he applied his eye again to the telescope, that it was not blinding. In fact, he could look at it as steadily as he could upon a clear sky.

But, gaze as he would, he could see nothing—nothing but light; subdued, soft, beautiful light. He knew the ray was passing steadily downward, for the mechanism was working with its accustomed regularity, but it revealed to him nothing at all. He could not understand it; his brain was dazed. He thought there might be something the matter with his eyesight. He got down from the ladder and hurriedly sent for Margaret, and when she came he begged her to look through the telescope and tell him what she saw. She went inside the screen, ascended the ladder, and looked down.

“It isn't anything,” she called out presently. “It looks like lighter air; it can't be that. Perhaps there is something the matter with your telescope.”

Clewe had thought of that, and as soon as she came out he examined the instrument, but the lenses were all right. There was nothing the matter with the telescope.

That night Roland Clewe spent in the lens-house, almost constantly at the telescope, but nothing did he see but a disk of soft, white light.

“The world can't be hollow!” he said to Margaret the next morning. “It can't be filled with air, or nothing, and my ray would not illuminate air or nothing. I cannot understand it. If you did not see what I see, I should think I was going crazy.”

“Don't talk that way,” exclaimed Margaret. “This may be some cavity which the ray will soon pass through, and then we shall come to the good old familiar rock again.”

But Clewe could not be consoled in this way. He could see no reason why his ray acting upon the emptiness of a cavern should produce the effect he beheld. Moreover, if the ray had revealed a cavern of considerable extent he could not expect that it could now pass through it, for the limit of its operations was almost reached. His electric cumulators would cease to act in a few hours more. The ray had now descended more than fourteen miles—its limit was fifteen.

Margaret was greatly troubled because of the effect of this result of the light borer upon Roland. His disappointment was very great, and it showed itself in his face. His Artesian ray had gone down to a distance greater than had been sometimes estimated as the thickness of the earth's crust, and the result was of no value. Roland did not believe that the earth had a crust. He had no faith in the old-fashioned idea that the great central portion was a mass of molten matter, but he could not drive from his mind the conviction that his light had passed through the solid portion of the earth, and had emerged into something which was not solid, which was not liquid, which was in fact nothing.

All his labors had come to this: he had discovered that the various strata near the earth's surface rested upon a vast bed of rock, and that this bed of rock rested upon nothing. Of course it was not impossible that the arrangement of the substances which make up this globe was peculiar at this point, and that there was a great cavern fourteen miles below him; but why should such a cavern be filled with a light different from that which would be shown by his Artesian ray when shining upon any other substances, open air or solid matter?

He could go no deeper down—at least at present. If he could make an instrument of increased power, it would require many months to do it.

“But I will do it,” said he to Margaret. “If this is a cavern, and if it has a bottom, I will reach it. I will go on and see what there is beyond. On such a discovery as I have made one can pass no conclusion whatever. If I cannot go farther, I need not have gone down at all.”

“No,” said Margaret, “I don't want you to go on—at least at present; you must wait. The earth will wait, and I want you to be in a condition to be able to wait also. You must now stop this work altogether. Stop doing anything; stop thinking about it. After a time—say early in winter—we can recommence operations with the Artesian ray; that is, if we think well to do so. You should stop this and take up something else. You have several enterprises which are very important and ought to be carried on. Take up one of them, and think no more for a few months of the nothingness which is fourteen miles below us.”

It was not difficult for Roland Clewe to convince himself that this was very good advice. He resolved to shut up his lens-house entirely for a time, and think no more of the great work he had done within it, but apply himself to something which he had long neglected, and which would be a distraction and a recreation to his disappointed mind.