And, as they walked, he told her the story. When he got through she stood and looked at him a long time in silence.
"You look square to me," she said. "You're working on my side already. Will you help me."
"I'll do anything—anything—" Phil said, and couldn't think of any other way of expressing his willingness, for the wonderful eyes bore radiantly upon him.
"First I must tell you my story," she began. "But before I can do so, you must promise me that it is to remain an absolute secret. You're a newspaper man—"
Phil gave his promise readily.
"My father is Professor Bloomsbury at the University of Chicago. He has been experimenting in mathematical physics, and I have been assisting him. He has succeeded in proving experimentally the concept of tensors. A tensor is a mathematical expression for the fact that space is smooth and flat, in three dimensions, only at an infinite distance from matter; in the neighborhood of a particle of matter, there is a pucker or a wrinkle in space. My father has found that by suddenly removing a portion of matter from out of space, the pucker flattens out. If the matter is heavy enough and its removal sudden enough, there is a violent disturbance of space. By planning all the steps carefully my father has succeeded in swinging a section of space on a pivot through an angle of 180 degrees, and causing two portions of space to change places through hyperspace, or as you might express it popularly, through the fourth dimension."
Phil held his hands to his head.
"It is not difficult," she went on smiling. "Loan me your pocket knife and a piece of paper from your notebook. If I cut out a rectangular piece of paper from this sheet and mount it on a pivot or shaft at A B, I can rotate it through 180 degrees, just like a child's teeter-totter, so that X will be where Y originally was. That is in two dimensions. Now, simply add one dimension all the way round and you will have what daddy is doing with space. He does it by shoving fifty or a hundred pounds of lead right out of space; the sudden flattening out of the tensors causes a section of space to flop around, and two portions of space change places. The first time he tried it, his desk disappeared, and we've never seen it again. We've thought it was somewhere out in hyperspace; but this terrible story of yours about disappearing safes, and the fact that you have this picture, means that someone has got the desk."
"Surely you must have suspected that long ago, when the disappearances first began?" Phil suggested.