“That, my dear sir, is an assumption which I must decline to confirm.” “Nevertheless, it is true. And here is another to go with it: _you know where that vein can be found!_” Hartridge smiled again. “You are, constructively at least, my guest, Mr. Carfax; I should be unpardonably rude if I were to contradict you.” Carfax glanced aside at Tregarvon, and Tregarvon returned the glance as one who sees the shore from the crest of a tossing wave, but has no hope of reaching it. After a little pause Carfax renewed the attack. “This is a most extraordinary situation, don’t you think, Mr. Hartridge?” he began mildly. “Would a definite quantity of the thing known commercially as money tend to relieve it in any way?” The professor’s answer was prompt and decisive. “You are assuming that I have information to sell? I have not.” Carfax countered, quickly. “Then why have you just given us this pointer on Consolidated Coal? You profess to be willing to help us and you refuse to help us in one and the same breath.” “Oh, if you are going into motives, my dear sir, that is, indeed, a very deep subject. It would hardly be profitable to discuss it, even academically. Life, the really human variety of life, is full of paradoxes. You are wondering why the man from whom, a few hours ago, you took that small cube of steel, is now apparently trying to save you from loss. Call it one of the human paradoxes, if you will; only don’t sell to Consolidated Coal for a paltry hundred thousand dollars a property upon which more than three or four times that amount has been spent. This is what I enticed you up here to say to you; and having said it----” “Hold on,” Carfax interposed. “We have met some curious varieties of the genus enemy in this forgotten corner of the world, and you will pardon me if I say that you are not the least remarkable specimen, Mr. Hartridge. We are thankful for the pointer, and much more thankful for the assurance you have given us that we are not fishing in a barren pond. We----” The professor had risen and was moving toward the door. “I have given you no such specific assurance,” he denied. “No,” said Tregarvon, getting upon his feet and putting in a word for himself. “You may congratulate yourself upon your discretion. None the less, we shall continue to work on our problem, Mr. Hartridge, until we have found the value of ‘_pi_’.” It was a centre shot, visibly and palpably piercing the bull’s-eye. A blow would scarcely have disconcerted the schoolmaster more effectively. Yet he recovered instantly, had blandly excused himself upon the plea of pressing laboratory work, and was bowing himself out at the door, when he fired the return shot. “You have set yourselves an impossible task, gentlemen,” he offered mildly. “You forget that the value of ‘_pi_’ has never yet been exactly ascertained.” “Well, what do you make of it all?” Tregarvon asked, when the yellow car was rolling smoothly down the mountain pike on the return to Coalville.