"This is an American-made pistol, and unless it happens to have been sold in England there is precious little chance of our discovering its owner." Tarling was looking at the weapon, turning it over and over in his hand.
Presently he looked at the butt and uttered an exclamation.

Following the direction of his eyes, Whiteside saw two deep furrows running diagonally across the grip.
"What are they ?" he asked.
"They look like two bullets fired at the holder of the revolver some years ago, which missed him but caught the butt." Whiteside laughed.
"Is that a piece of your deduction, Mr.Tarling ?" he asked.
"No," said Tarling, "that is a bit of fact.

That pistol is my own!".