"I think so. Mr. Brotherson - the Brooklyn one,- is up in his shed. He sleeps there now, I am told, and soundly too I've no doubt."

"What half the inventors on both sides of the water are engaged upon just now. A monoplane, or a biplane, or some machine for carrying men through the air. I know, for I helped him with it. But you'll find that if he succeeds in this undertaking, and I believe he will, nothing short of fame awaits him. His invention has startling points. But I'm not going to give them away. I'll be true enough to him for that. As an inventor he has my sympathy; but - Well, we will see what we shall see, to-morrow. You say that he is bound to be present when Miss Scott relates her tragic story. He won't be the only unseen listener. I've made my own arrangements with Miss Scott. If he feels the need of watching her and his brother Oswald, I feel the need of watching him."

"You take a burden of intolerable weight from my shoulders. Now I shall feel easier about that interview. But I should like to ask you this: Do you feel justified in this continued surveillance of a man who has so frequently, and with such evident sincerity, declared his innocence?"

"I do that. If he's as guiltless as he says he is, my watchfulness won't hurt him. If he's not, then, Mr. Challoner, I've but one duty; to match his strength with my patience. That man is the one great mystery of the day, and mysteries call for solution. At least, that's the way a detective looks at it."

" May Heaven help your efforts!"

"I shall need its assistance," was the dry rejoinder. Sweetwater was by no means blind to the difficulties awaiting him.

The day was a grey one, the first of the kind in weeks. As Doris stepped into the room where Oswald sat, she felt how much a ray of sunshine would have encouraged her and yet how truly these leaden skies and this dismal atmosphere expressed the gloom which soon must fall upon this hopeful, smiling man.

He smiled because any man must smile at the entrance of so lovely a woman, but it was an abstracted smile, and Doris, seeing it, felt her courage falter for a moment, though her steps did not, nor her steady compassionate gaze. Advancing slowly, and not answering because she did not hear some casual remark of his, she took her stand by his side and then slowly and with her eyes on his face, sank down upon her knees, still without speaking, almost without breathing.