“Oh, dear, no, not a bit; they’re as different as day and night. He’s only her half-brother anyway. She was the daughter of the Colonel’s second wife. Our Madam is the sweetest, gentlest lady you can imagine, an angel of goodness. But the Lieutenant here has always been a care to his family, they say. I guess he’s quieted down a bit now, for his father—he’s Colonel Leining, retired—made him get exchanged from the city to a small garrison town. There’s nothing much to do in Marburg, I dare say—well! you are a merry sort, aren’t you?” These last words, spoken in a tone of surprise, were called forth by a sudden sharp whistle from the detective, a whistle which went off into a few merry bars.
A sudden whistle like that from Muller’s lips was something that made the Imperial Police Force sit up and take notice, for it meant that things were happening, and that the happenings were likely to become exciting. It was a habit he could control only by the severest effort of the will, an effort which he kept for occasions when it was absolutely necessary. Here, alone with the harmless old man, he was not so much on his guard, and the sudden vibrating of every nerve at the word “Marburg,” found vent in the whistle which surprised old Franz. One young police commissioner with a fancy for metaphor had likened this sudden involuntary whistle of Muller’s to the bay of the hound when he strikes the trail; which was about what it was.
“Yes, I am merry sometimes,” he said with a laugh. “It’s a habit I have. Something occurred to me just then, something I had forgotten. Hope you don’t mind.”
“Oh, no, there’s no one here now, whistle all you like.”
But Muller’s whistle was not a continuous performance, and he had now completely mastered the excitation of his nerves which had called it forth. He threw another sharp look at the picture of the man who lived in Marburg, and then asked: “And now where is the button?”
“By the window there, beside the desk.” Franz led the way with his candle.
“Why, how funny! What are those mirrors there for?” asked the electrician in a tone of surprise, pointing to two small mirrors hanging in the window niche. They were placed at a height and at such a peculiar angle that no one could possibly see his face in them.
“Something the master is experimenting with, I guess. He’s always making queer experiments; he knows a lot about scientific things.”
Muller shook his head as if in wonderment, and bent to investigate the button which was fastened into the wall beneath the window sill. His quick ear heard a carriage stopping in front of the house, and heard the closing of the front door a moment later. To facilitate his examination of the button, the detective had seated himself in the armchair which stood beside the desk. He half raised himself now to let the light of the candle fall more clearly on the wiring—then he started up altogether and threw a hasty glance at the mirrors above his head. A ray of light had suddenly flashed down upon him—a ray of red light, and it came reflected from the mirrors. Muller bit his lips to keep back the betraying whistle.
“What’s the matter?” asked the butler. “Did you drop anything?”