And yet, not one of all those sounds but echoed more bitter slavery for men.  Not one of all those many activities but boded ill to humanity.  For the whole plan and purpose of the place was the devising of still wider forms of human exploitation and enslavement.  Its every motive was to serve the greed of Flint and Waldron.  Outwardly honest and industrious, it inwardly loomed sinister and terrible, a type and symbol of its masters’ swiftly growing power.  Such, in its essence, was the great experiment station of these two men who lusted for dominion over the whole world.

As the long, glittering car drew up at the main gate of the enclosure, a sharp-eyed watchman peered through a sliding wicket therein.  Satisfied by his inspection, he withdrew; and at once the big gate rolled back, smoothly actuated by electricity.  The car purred onward, into the enclosure.  When the gate had closed noiselessly behind it, the chauffeur ran it down a splendidly paved roadway, swung to the right, past the machine shops, and drew it to a stand in front of the administration building.

Flint and his partner alighted, and stood for a moment surveying the scene with satisfaction.  Then Flint turned to the chauffeur.

“Put the car in the garage,” he directed.  “We may not want it till afternoon.”

The blase one touched his cap and nodded, in obedience.  Then, as the car withdrew, the partners ascended the broad steps.

“Good chap, that Herrick,” commented Waldron, casting a glance at the retreating chauffeur.  “Quick-witted, and mum.  Give me a man who knows how to mind and keep still about it, every time!”

“Right,” assented Flint.  “Obedience is the first of all virtues, and the second is silence.  Well, it looks to me as though we had the whole world coming our way, now, along that very same path of virtue.  Once we get this air proposition really to working, the world will obey.  It will have to!  And as for silence, we can manage that, too.  The mere turn of a valve, and—!”

Waldron smiled grimly, as though in derision of what he seemed to think his partner’s chimerical hopes, but made no answer.  Together they entered the administration building.  Five minutes later, Herzog, their servile experimenter, stood bowing and cringing before them.

“Got it, Herzog?” demanded Flint, while Waldron lighted still another of those costly cigars—­each one worth a good mechanic’s daily wage.

“Yes, sir, I believe so, sir,” the scientist replied, depreciatingly.  “That is, at least, on a small scale.  Two weeks was the time you allowed me, sir, but—­”

“I know.  You’ve done it in eleven days,” interrupted, the Billionaire.  “Very well.  I knew you could.  You’ll lose nothing by it.  So no more of that.  Show us what you’ve done.  Everything all ready?”

“Quite ready, sir,” the other answered.  “If you’ll be so good as to step into the electro-chemical building?”