In the two undivided faces of the cube, relatively squaring the center, were four borings somewhat smaller in diameter than an ordinary pencil, and extending through; and directly in the center was focused a network of insulated wires which dropped down out of the gloom overhead. In the other two sides of the great cube, just where the dividing lines of the halves came, were the funnel-like mouths of a two-inch boring. This, too, extended straight through.
Directly opposite each of the two mouths, a dozen feet away, was mounted a peculiarly-constructed heavy gun of the naval type. In a general sort of way these were not unlike twelve-inch ordnance, but the breech was much larger in proportion, the barrel longer, and the bore only two instead of twelve inches. The mountings were high, and the adjustment so delicate that, looking into the open breech of one gun, the bore through the twenty-foot cube and through the barrel of the gun on the other side seemed to be continuous.
"This is the diamond-making machine, gentlemen," said Mr. Wynne, and he indicated to Mr. Latham, Mr. Schultze and Mr. Czenki the cube and the two guns. "It is perfectly simple in construction, has enormous powers of resistance, as you may guess, and is as delicately fitted as a watch, being regulated by electric power. This cube is the solution of the high-pressure, high-temperature problem, which was only one of the many seemingly insuperable obstacles to be overcome. When the bolts are withdrawn one half slides back; when the bolts are in position it is as solid as if it were in one piece, and perfectly able to withstand a force greater than the ingenuity of man has ever before been able to contrive. This force is a combination of a heat one-half that of the sun on its surface, and a head-on impact of two one-hundred-pound projectiles fired less than forty feet apart with an enormous charge of cordite, and possessing an initial velocity greater than was ever recorded in gunnery.
"This vast force centers in a sort of furnace in the middle of the cube. The furnace is round, about three feet long and three feet in diameter, built of half a dozen fire-resisting substances in layers, perforated for electric wires, with an opening through it lengthwise of the exact size of the borings in the guns and in the cube. It fits snugly into a receptacle cut out for it in the center of the cube, and is intended to protect the steel of the cube proper from the intense heat. This heat reaches the furnace by electric wires which enter the cube from the sides, as you see, being brought here by a conduit along the river-bed from a large power-plant five miles away. Twenty-eight large wires are necessary to bring it; I own the power-plant, ostensibly for the operation of a small sugar refinery. I may add that the furnace is a variation of the principle employed by Professor Moissan, in Paris." He turned to Mr. Czenki. "You may remember having heard me mention him?"
"I remember," the expert acquiesced grimly.
"Now, pure carbon is vaporized, as you perhaps know, at a fraction less than five thousand degrees Fahrenheit," Mr. Wynne continued. "A carbon not merely chemically pure but absolutely pure, in highly compressed disks, is packed in the furnace, the furnace placed within the cube, the ends of the two-inch opening in the furnace being blocked to prevent expansion, the cube closed, the bolts fastened, and heat applied, for several minutes—a heat, gentlemen, of five thousand two hundred and eighty degrees Fahrenheit. The heat of the sun is only about ten thousand degrees. And then the pressure of about seven thousand tons to the square inch is added by means of the two guns. In other words, gentlemen, pure carbon, vaporized, is caught between two projectiles which enter the cube simultaneously from opposite sides, being fired by electricity. The impact is so terrific that what had been two feet of compressed carbon is instantly condensed into an irregular disk, one inch or an inch and a half thick. And that disk, gentlemen, is a diamond!
"The violence of the operation, coupled with the intense heat, fuses everything—furnace, projectiles, electric wires, fire-brick, even asbestos, into a single mass. The cube is opened, and this mass, white-hot, is dropped into cold water. This increases the pressure until the mass is cool. Then it is broken away, and in the center is a diamond—as big as a biscuit, gentlemen! Four small bores lead from the two-inch bore through the cube, and permit the escape of air as the projectiles enter. There is no rebound because the elastic quality of the carbon is crushed out of existence—driven, I may say, into the diamond itself. Of course the furnace, the two projectiles and the connecting electric wires are all destroyed at each charge, which brings the total cost of the operation to a little more than eight hundred dollars, including nearly three tons of brown sugar. The diamond resulting is worth at least a million when broken up for cutting, sometimes even two millions. That is all, I think."
There was a long, awed silence. Mr. Latham, leaning against the giant cube, stared thoughtfully at his toes; Mr. Schultze was peering curiously about him, thence off into the gloom; Mr. Czenki still had a question.
"I understand that all the diamonds were made in that disk-like shape," he remarked at last. "Then the uncut stones that were stolen were—"
"They were natural stones," interrupted Mr. Wynne, "imported for purposes of study and experiment. I told Chief Arkwright the truth, but not all of it. In the last twenty years Mr. Kellner had destroyed some twenty thousand dollars' worth of diamonds in this way. I may add that while Mr. Kellner had succeeded in making diamonds of large size he had never made a perfect one until eight years ago. But meanwhile the expenses of the work, as you will understand, were enormous, so during the past eight years about a million dollars' worth of diamonds have been sold, one or two at a time, to meet this expense."