Rob was perfectly at home in these queer surroundings; among them she had spent a great deal of her childhood, creeping, "mousy-quiet," to sit on a stool by her oblivious father, her chattering tongue silenced and her busy brain full of loving awe. Her father looked up now as she entered. "Ah, Rob, come in," he said. "I want to go over this with you. You read to me what I have written here, while I move the model according to those directions, and see if I have made it clear and correct." "Yes, Patergrey," said Rob, taking the closely written manuscript which he handed her, well used to this sort of service. And then she began to read. Sometimes, not fully understanding what she read, Rob paused and watched her father manipulate the model, and refer to its sections, until she comprehended perfectly what the words were intended to convey. So far from this interest on her part annoying the inventor, it delighted him, and largely explained what was unquestionably true--that Rob was his favorite daughter. "You will be as well able to exhibit this as I shall when it is done, Rob, my son," Mr. Grey laughed, well pleased, as, her point cleared up, Roberta read on, pausing only at a word from her father. "Wait a moment, Rob; this isn't quite right." "Mark that with the blue pencil, Rob; I'll say that more briefly." "Slowly, Rob; my fingers won't move as fast as your tongue." At last they were through, and Mr. Grey threw himself into his big chair with the shabby cushions, sighing contentedly. "That's all right, Rob," he said. "Next autumn will see the machine completed--December at the latest, I hope. What a help you are, Rob, my son!" "It's a comfort to hear you say that, like a sort of grace, every time we get through, Patergrey," said Rob. "But if I am a help to you, I wonder if I can get you to do something for me?" "Yes, you know you can," said Mr. Grey, anticipating a request to be taken fishing, or to go for a long stroll in the twilight. But Rob, who would never allow anyone to insinuate that her father could accomplish more than he did, had other plans in her teeming brain. With a sensitive flush, fearing to wound her father, she said: "Didn't you tell me, Patergrey, that a magazine had asked you to write a special article for it on something or other scientific, and offered you quite a sum of money if you'd do it?" "Why, yes," said Mr. Grey, startled into animation by the unexpected question. "On fuels and means of heating and lighting in the future, and the world's storage of such fuel; they thought I should be prepared for such an article--as I am. Yes, they asked me--why?"