The young lady took out her watch. "You had better be thankful that I'm not the man-eating variety--it's nearly lunch-time!" If Professor Hooker's eyes had been as sensitive to delicate shades of the complexion as they were to the varied hues shown in his spectrophotometer, he would have noticed that a pink flush--very nearly wave-length 6250, he would have said--spread over her face as she caught his eye; but this incident wholly escaped his notice. At the same moment, the bellow of a factory whistle somewhere over Alexandria way caused Professor Hooker to arouse himself out of his state of semilethargy. "By thunder, it's one o'clock!" he exclaimed, and, without further ado, he arose, bolted across the Circle, and made a flying leap for a street-car which was just swinging into Connecticut Avenue. The tailor-made girl followed him with an amused gaze. "I really believe I know more mathematics than he does," she remarked complacently to herself. "But isn't he just a dear?" And with that, she too, arose and walked briskly away, as if she knew exactly where she was going--which she did. III He was fifteen minutes late to lunch, and the other boarders had made way with everything on the table except a single chop and a few scrapings of macaroni which Mrs. Mullins, the landlady, had carefully rescued and preserved for him. But Professor Hooker, who ate merely as a matter of form, did not notice the absence of the other courses and, automatically obeying the law of compensation, evened up on the sago pudding, of which there was an inevitable abundance. Then he went up to his room, lit his pipe, seated himself, cross-legged, sideways on his bed, and got to work at his note-book again. The equation, however, in spite of the young lady's clever suggestions, still refused to be solved. For an hour, he chewed his pencil, arising occasionally and walking up and down, three steps each way, in front of the marble-topped walnut bureau, until the middle-aged spinster who occupied the room below was ready to scream with nerves. As however, she was waiting for a man to come and take her out walking, she was obliged to possess her soul and feet in patience. * * * * * "I ought to have let that young woman finish up this calculation for me." Hooker at last conceded to the face in the glass. "I can't handle the thing myself, and now I'll have to go out to Georgetown and bother Thornton with it."