The gate closed, a gong rang twice, somewhere up ahead an engine gave half a dozen spasmodic coughs, and the forward section of the train began to pull out. McAllister, gasping for breath, a terrible pain in his side, his ulster seeming to weigh a thousand pounds, stumbled upon the platform of the car next the last. As he did so, the slim young man rushed to the gate and commenced to beat frantically upon it. The gate-man, indignant, approached to make use of severe language. "Open this gate!" yelled the man. "There's a burglar in disguise on that train. Didn't you see him run through? Open up!" "Whata yer givin' us?" answered Gate. "Who are yer, anyhow?" "I'm a detective sergeant!" shrieked the one outside, excitedly exhibiting a shield. "I order you to open this gate and let me through." Gate looked with exasperating deliberateness after the receding train; its red lights were just passing out of the station. "Oh, go to--!" said he through the bars. * * * * * "Is this car 2241?" inquired the breathless McAllister at the same moment, as he staggered inside. "Sho, boss," replied the porter, grinning from ear to ear as he received the ticket and its accompanying half-dollar. "Drawin'-room, sah? Yes-sah. Right here, sah! Yo' frien', he arrived some time ago. May Ah enquire what personage yo represent, sah? A most magnificent sword, sah!" "Where's the smoking compartment?" asked McAllister. "Udder end, sah!" Now McAllister had no inclination to feel his way the length of that swaying car. He perceived that the smoking compartment of the car behind would naturally be much more convenient. "I'm going into the next car to smoke for a while," he informed the darky. No one was in the smoking compartment of the Benvolio, which was bright and warm, and McAllister, throwing down his ulster, stretched luxuriously across the cushions, lit a cigar, and watched with interest the myriad lights of the Greater City marching past, those near at hand flashing by with the velocity of meteors, and those beyond swinging slowly forward along the outer rim of the circle. And the idea of this huge circle, its circumference ever changing with the forward movement of its pivot, beside which the train was rushing, never passing that mysterious edge which fled before them into infinity, took hold on McAllister's imagination, and he fancied, as he sped onward, that in some mysterious way, if he could only square that circle or calculate its radius, he could solve the problem of existence. What was it he had learned when a boy at St. Andrew's about the circle? Pi R--one--two--two Pi R! That was it! "2πr." The smoke from his cigar swirled thickly around the Pintsch light in the ceiling, and Henry VIII, oblivious of the anachronism, with his sword and feathered cap upon the sofa beside him, gazed solemnly into space. "Br-r-clink!--br-r-clink!" went the track. "Two Pi R!" murmured McAllister. "Two Pi R!" III