Fay straightened his back. He tried to pierce the gloom in the direction of Saidee Isaacs. He glanced down at the table. The sheet of paper had been whisked away by Sir Richard, who placed it in the box.
MacKeenon switched on the light. The room was filled with dazzling brilliancy. Sir Richard pointed to the sheath of cipher papers which were piled in the tin containers.
“See anything there now?� he asked Fay.
The cracksman passed his hand over his eyes and stared at the topmost sheet. The cipher-writing had vanished. The lines of letters, which had been typed for a blind, alone showed.
“Now I know,� sad Fay, “how Ace-in-the-hole Harry worked the gulls on the passenger boats. He
wore heavy smoked glasses and marked the backs of the cards with phosphor or luminous paint. It was the same thing as putting the light out—as far as he was concerned.â€�
“The trifles!� chuckled Sir Richard. “You threw Mononsonburg’s key away. Those glasses were thick enough and dark enough to read the writing on the sheets in daylight. The secrets of the German dyes are written between the lines by a fine pen dipped in radium salts.�
The Prime Minister drew out a flat watch and consulted it. He turned toward two men high in the Government whom Sir Richard had called.
“Gentlemen,� he said, “we must be going. Sir Richard has entertained us exceedingly. I’d sum the matter up by saying everything was tried except putting out the light. But then, who would have thought of so simple a thing as that?�
Sir Richard nodded to Saidee Isaacs.