He turned a switch, made some adjustments, and grasped the handles on the varnished box, which thereupon emitted a low hymenopterous humming, and advanced upon the dollar like a hunter stalking skittish game. As he neared the coin, the humming began to keen up the scale. He stood still, and the sound held steady; again toward the dollar and the wail of the box slid up and up until, held directly above the coin, it gave forth the whine of a band saw eating into a pine knot.
The Saint walked over and inspected the setup. He picked up the dollar and tossed it back to the bartender.
“Let’s see what it does about this change in my pocket,” he said, slapping his trouser leg.
Mr McDill moved the device over the indicated area, but the humming remained at a low murmur. He ceased his efforts and grinned.
“You ain’t got any change in your pocket, mister.”
Grinning in turn, the Saint pulled out the pocket. It was empty.
“Can’t fool the Doodlebug,” said McDill complacently. “See” — he held the box for the Saint to look at — “it works the same way for any other kind o’ metal.”
The Saint duly noted the markings etched along the sliding scale on top. He moved the indicator to “Gold,” and the Doodlebug, which had been humming like a happy bee, suddenly whined like an angry mosquito. The Saint jerked back his left wrist with the gold watch on it, and the machine dropped again to a gentle hum. McDill set it on the bar, and it fell completely silent.
“Ain’t she a beauty?” the little man demanded.
“Lovely,” Simon agreed. “Just what you need any time you drop a silver dollar.”