building, he was hesitant about
approaching it. Tony knew him, and might see him first. Phil circled
the brick building, keeping under cover or far enough away; all around
it was a belt of thirty feet of lawn between the building and the
sidewalk. Ought he have called the police and given them his idea? Or
should he wait till darkness and see what he could do alone?

Then suddenly he saw her. Across the street, standing in the shelter
of a delivery truck in front of an apartment, she was observing Tony's
building intently. The aristocratic chin, the brightness of the eyes,
the waves of her hair, and the general sunny expression! It could not
be anyone else. Post haste he ran across the street.

"Pardon me!" he cried excitedly, lifting his hat and then digging
hastily into his inner pocket. "I'm sure you must be the--"

"Well, the nerve!" the young woman said icily, and pointing her chin
at the opposite horizon she walked haughtily away.

By that time Phil had dug out his picture and was running after her.

"Please," he said, "just a moment!" And he held the picture out in
front of her face.

"Now, where in the world--?" She looked at him in puzzled and
indignant inquiry, and then burst out laughing.

"It _is_ you, isn't it?" Phil asked. "What are you laughing at?"

"Oh, you looked so abject. I'm sure your intentions must be good. Now
tell me where you got my picture."

"Let us walk this way," suggested Phil, leading away from Tony's
building.

* * * * *

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 neighborh