"Why, dash it all, this is clear madness," cried Lord John. "Each of us seems to know what the others did and none of us knows what he did himself. Let's put it all together from the first. We got into a first-class smoker, that's clear, ain't it? Then we began to quarrel over friend Challenger's letter in the Times." "Oh, you did, did you?" rumbled our host, his eyelids beginning to droop. "You said, Summerlee, that there was no possible truth in his contention." "Dear me!" said Challenger, puffing out his chest and stroking his beard. "No possible truth! I seem to have heard the words before. And may I ask with what arguments the great and famous Professor Summerlee proceeded to demolish the humble individual who had ventured to express an opinion upon a matter of scientific possibility? Perhaps before he exterminates that unfortunate nonentity he will condescend to give some reasons for the adverse views which he has formed." He bowed and shrugged and spread open his hands as he spoke with his elaborate and elephantine sarcasm. "The reason was simple enough," said the dogged Summerlee. "I contended that if the ether surrounding the earth was so toxic in one quarter that it produced dangerous symptoms, it was hardly likely that we three in the railway carriage should be entirely unaffected." The explanation only brought uproarious merriment from Challenger. He laughed until everything in the room seemed to rattle and quiver. "Our worthy Summerlee is, not for the first time, somewhat out of touch with the facts of the situation," said he at last, mopping his heated brow. "Now, gentlemen, I cannot make my point better than by detailing to you what I have myself done this morning. You will the more easily condone any mental aberration upon your own part when you realize that even I have had moments when my balance has been disturbed. We have had for some years in this household a housekeeper--one Sarah, with whose second name I have never attempted to burden my memory. She is a woman of a severe and forbidding aspect, prim and demure in her bearing, very impassive in her nature, and never known within our experience to show signs of any emotion. As I sat alone at my breakfast--Mrs. Challenger is in the habit of keeping her room of a morning--it suddenly entered my head that it would be entertaining and instructive to see whether I could find any limits to this woman's inperturbability. I devised a simple but effective experiment. Having upset a small vase of flowers which stood in the centre of the cloth, I rang the bell and slipped under the table. She entered and, seeing the room empty, imagined that I had withdrawn to the study. As I had expected, she approached and leaned over the table to replace the vase. I had a vision of a cotton stocking and an elastic-sided boot. Protruding my head, I sank my teeth into the calf of her leg. The experiment was successful beyond belief. For some moments