"We'll do what we can," Wade told him gloomily. "But it's going to be pretty hard to keep the force looking for someone they can't see! Even if they believe in the story at all. But I wouldn't worry about the thing, sir—visible or invisible, a crook can only keep free so long when thousands are concentrating on finding him."
"I sincerely hope you're right," said President Ellsworth as he turned to the door, hat in hand. "I'll see you tomorrow about it, Grantham—and take care of yourself until then."
When he had gone Dr. Grantham said quietly, "I am glad that he does not fully realize the appalling nature of this thing. I did not want to worry him to no purpose. Whether it was Gray who took the projector or another, is really immaterial now. The fact, the great fact, is that someone has it who has proved himself ruthless. And with it, he can loose such a terror upon New York—yes and upon the nation—as might be utterly without precedent!"
"One man?" asked Wade, skeptically.
"One man—but an invisible one!" Grantham exclaimed. "Have you realized what this means? It means that there are no limits to this man's power, whoever he is. It means that he can strike down any he wishes though that person surround himself with a thousand body-guards. It means that there is no fortress or strong-room that can keep him out, nothing that he cannot take for himself in full light of day. He can be, if he desires, an invisible tyrant ruling the world with terror!"
Wade's face was graver as he turned with Grantham, and with Carton and Burns to the door.
"Well, the most we can hope for now is to get him before he can use the thing," he said. "Whether it's Gray or another, we ought to be able somehow to——"
He halted, and his hand shot forward to a little table just inside the door. On it rested a big square white envelope addressed in a bold hand to "Dr. Grantham."
Wade's countenance was impassive as he grasped it. "This wasn't here when President Ellsworth left," he said. "I saw him take his hat from that table. Is that Gray's handwriting?"
"That or a good imitation of it," said Grantham slowly.