I come now to a part of my narrative which would have been deemed altogether incredible in those closing years of the nineteenth century that witnessed the first steps towards the solution of the deepest mysteries of the ether, although men even then held in their hands, without knowing it, powers which, after they had been mastered and before use had made them familiar, seemed no less than godlike.
For six months after Hall’s departure for San Francisco I heard nothing from him. Notwithstanding my intense desire to know what he was doing, I did not seek to disturb him in his retirement. In the meantime things ran on as usual in the world, only a ripple being caused by renewed discoveries of small nuggets of artemisium on the Tetons, a fact which recalled to my mind the remark of my friend when he dislodged a flake of the metal from a crevice during our ascent of the peak. At last one day I received this telegram at my office in New York:
“SAN FRANCISCO, May 16, 1940.
“Come at once. The mystery is solved.
“(Signed) HALL.”
As soon as I could pack a grip I was flying westward one hundred miles an hour. On reaching San Francisco, which had made enormous strides since the opening of the twentieth century, owing to the extension of our Oriental possessions, and which already ranked with New York and Chicago among the financial capitals of the world, I hastened to Hall’s laboratory. He was there expecting me, and, after a hearty greeting, during which his elation over his success was manifest, he said:
“I am compelled to ask you to make a little journey. I found it impossible to secure the necessary privacy here, and, before opening my experiments, I selected a site for a new laboratory in an unfrequented spot among the mountains this side of Lake Tahoe. You will be the first man, with the exception of my two devoted assistants, to see my apparatus, and you shall share the sensation of the critical experiment.”
“Then you have not yet completed your solution of the secret?”
“Yes, I have; for I am as certain of the result as if I had seen it, but I thought you were entitled to be in with me at the death.”
From the nearest railway station we took horses to the laboratory, which occupied a secluded but most beautiful site at an elevation of about six thousand feet above sea-level. With considerable surprise I noticed a building surmounted with a dome, recalling what we had seen from the Grand Teton on the roof of Dr. Syx’s mill. Hall, observing my look, smiled significantly, but said nothing. The laboratory proper occupied a smaller building adjoining the domed structure. Hall led the way into an apartment having but a single door and illuminated by a skylight.
“This is my sanctum sanctorum,” he said, “and you are the first outsider to enter it. Seat yourself comfortably while I proceed to unveil a little corner of the artemisium mystery.”
Near one end of the room, which was about thirty feet in length, was a table, on which lay a glass tube about two inches in diameter and thirty inches long. In the farther end of the tube gleamed a lump of yellow metal, which I took to be gold. Hall and I were seated near another table about twenty-five feet distant from the tube, and on this table was an apparatus furnished with a concave mirror, whose optical axis was directed towards the tube. It occurred to me at once that this apparatus would be suitable for experimenting with electric waves. Wires ran from it to the floor, and in the cellar beneath was audible the beating of an engine. My companion made an adjustment or two, and then remarked:
“Now, keep your eyes on the lump of gold in the farther end of the tube yonder. The tube is exhausted of air, and I am about to concentrate upon the gold an intense electric influence, which will have the effect of making it a kind of kathode pole. I only use this term for the sake of illustration. You will recall that as long ago as the days of Crookes it was known that a kathode in an exhausted tube would project particles, or atoms, of its substance away in straight lines. Now watch!”
I fixed my attention upon the gold, and presently saw it enveloped in a most beautiful violet light. This grew more intense, until, at times, it was blinding, while, at the same moment, the interior of the tube seemed to have become charged with a luminous vapor of a delicate pinkish hue.
“Watch! Watch!” said Hall. “Look at the nearer end of the tube!”
“Why, it is becoming coated with gold!” I exclaimed.
He smiled, but made no reply. Still the strange process continued. The pink vapor became so dense that the lump of gold was no longer visible, although the eye of violet light glared piercingly through the colored fog. Every second the deposit of metal, shining like a mirror, increased, until suddenly there came a curious whistling sound. Hall, who had been adjusting the mirror, jerked away his hand and gave it a flip, as if hot water had spattered it, and then the light in the tube quickly died away, the vapor escaped, filling the room with a peculiar stimulating odor, and I perceived that the end of the glass tube had been melted through, and the molten gold was slowly dripping from it.
“I carried it a little too far,” said Hall, ruefully rubbing the back of his hand, “and when the glass gave way under the atomic bombardment a few atoms of gold visited my bones. But there is no harm done. You observed that the instant the air reached the kathode, as I for convenience call the electrified mass of gold, the action ceased.”
“But your anode, to continue your simile,” I said, “is constantly exposed to the air.”
“True,” he replied, “but in the first place, of course, this is not really an anode, just as the other is not actually a kathode. As science advances we are compelled, for a time, to use old terms in a new sense until a fresh nomenclature can be invented. But we are now dealing with a form of electric action more subtile in its effects than any at present described in the text-books and the transactions of learned societies. I have not yet even attempted to work out the theory of it. I am only concerned with its facts.”
“But wonderful as the exhibition you have given is, I do not see,” I said, “how it concerns Dr. Syx and his artemisium.”
“Listen,” replied Hall, settling back in his chair after disconnecting his apparatus. “You no doubt have been told how one night the Syx engine was heard working for a few minutes, the first and only night work it was ever known to have done, and how, hardly had it started up when a fire broke out in the mill, and the engine was instantly stopped. Now there is a very remarkable story connected with that, and it will show you how I got my first clew to the mystery, although it was rather a mere suspicion than a clew, for at first I could make nothing out of it. The alleged fire occurred about a fortnight after our discovery of the double tunnel. My mind was then full of suspicions concerning Syx, because I thought that a man who would fool people with one hand was not likely to deal fairly with the other.
“It was a glorious night, with a full moon, whose face was so clear in the limpid air that, having found a snug place at the foot of a yellow-pine-tree, where the ground was carpeted with odoriferous needles, I lay on my back and renewed my early acquaintance with the romantically named mountains and ‘seas’ of the Lunar globe. With my binocular I could trace those long white streaks which radiate from the crater ring, called ‘Tycho,’ and run............