The Dark Eyes of London by Edgar Wallace

She nodded, took out a telegram form from her rack, and began writing. Larry glanced through the reports mechanically, initialled one, and put the others aside.

Then he opened the cupboard and, taking out the tray, carried it to the table. He examined the watch again in the light of day, the swivel ring, the cigar-case, and lastly the roll of paper. By daylight the embossed characters were visible, and he put his finger-tips over them very gingerly. He was not, however, accustomed to reading Braille, and he realized that his hand was a heavy one compared with the delicate touch of his secretary. She had finished her writing, and rung a bell and handed the telegram to him to read.