"It got smaller," hazarded the Saint.
"It caused terrific pressure," said Mr. Fallen firmly. "Just imagine it. Thousands of millions of tons of rock — and—"
"And rock."
"And rock, cooling down, and shrinking up, and getting hard. Well, naturally, any bits of carbon that were floating around in the rock got squeezed. So what happened?" demanded Louie, triumphantly reaching the climax of his lucid description.
He paused dramatically, and the Saint wondered whether he was expected to offer any serious solution to the riddle; but before he had really made up his mind, Mr. Fallon was solving the problem for him.
"I'll tell you what happened," said Mr. Fallon impressively, leaning over into a strategic position in which he could tap the Saint on the shoulder. Once again he paused, but there was no doubt that this hiatus at least was motivated solely by the requirements of theatrical suspense. "Diamonds!" said Mr. Fallon, with an air of patronizing pride which almost suggested that he personally had been responsible for the event.
The Saint took a draught from his glass, and gazed at him with that air of slightly perplexed awe which was one of the most precious assets in his infinitely varied stock of facial expressions. It was a gaze pregnant with so much ingenuous interest, such naive wonder and curiosity, that Mr. Fallon felt the cockles of his heart warming to a temperature at which, on a cold day, he would be tempted to dispense with his overcoat. Since he was not wearing an overcoat, he gave rein to his emotions by insisting that he should stand another round of drinks.
"Yes," he resumed, when he had refilled their glasses. "Diamonds. And that's how I make them — not," he admitted modestly, "that I mean I make the earth go hot and then cool down again. But I do the same thing on a smaller scale."
The Saint knitted his brows. It was the most ostentatious sign of a functioning brain that he could permit himself in the part he was playing.
"Now you tell me, I think I have heard something like that before," he said. "Hasn't somebody else done the same thing — I mean made synthetic diamonds by cooling chunks of iron under pressure?"