"Pass on! Pass on!" boomed the tyrant, and as there was a difference of at least three octaves between the two men's voices, the unfortunate Professor obeyed the double bass, crossed the street at the risk of his life, and wandered inanely past the shop windows. But there is a Providence for such as he, as also for drunkards and babes; and there, right before him, was an ancient bow window of bottle-glass panes; the name of the shop in old Georgian script; the information that it had been founded in 1805; and, behind the glass, two telescopes, a microscope, a clock, several watches, and a sextant of immense age. The Professor went in. "What I want ... ah!" he said. Then his eye fell upon the very thing he desired. It lay there in a glass case, and the owner of the shop, no younger than his customer, brought it out with a palsied hand. "That's it," said the Professor, nodding genially. "That's it. That's what I want. That's it." Slipping it into his pocket, he made for the door, nodding good day. "Hi! Mister! That'll be five guineas," said the ancient. Oh! vileness of avaricious age! He had seen his client coming out by the garden gate by the Great House, he had noted guilty haste, he had noted academic idiocy, and he charged accordingly. "Oh, yes! Of course ... ah! _What_! Five guineas? ... five _guineas_! FIVE GUINEAS!" It was a sickener. But the wages of Sin is Death. He must have it--or something of the sort. And he must have it now, before Humphrey got home. Sin will not wait. [Illustration: _Deplorable moral lapse of Professor de Bohun (pronounced Boon)._] Believe me or not, but there was positively a flush upon the yellow cheek of the hoary intriguer, a flush that contrasted charmingly with his straggling white whiskers, as he parted with two half crowns and a note. It was a severe struggle. To comfort himself he pressed the stud again. Yes, it worked all right. He toddled back, and got in at the very moment when his cousin's car was buzzing up the drive, back from London. Professor de Bohun was determined to lose no time. He got rid of his overcoat and his hat with surprising agility, and met the master of the house at the door as though he had been in for hours. But his was not a temperament to introduce a subject with finesse. He went blindly at it. "Humphrey," he said, ere ever the Home Secretary was across the step, "I want to see you. I want to see you now ... yes, now ... rather urgently.... I want to see you now." The Man of Little Peace nodded wearily. "Come along," he said. His mind jumped back to the false scent of the morning. He suddenly wondered whether, after all, Cousin Bill was going to confess? Galton's statement had been clear enough. He had said in so many words that he had _seen_ an emerald in the Professor's hand. And the head of the family would have believed anything, almost of the Professor in the way of such follies since the great Mullingar affair.