"Wait a bit, sir!" said Wake. "I've seen those vices. You can tilt the rifle any way you please in them, so even allowing for the bridge's being a good way below the sapling, why would anyone fix the rifle up so close to the ground? For the grazes weren't but a foot or two up, were they?"
Hemingway was not in the least put out of countenance by this. He said briskly: "We'll probably find there was a reason for that. As a matter of fact, I've found it already. There's a drop of seven or eight feet to the level of the bridge, and it stands to reason our bird wanted to get as low a trajectory as possible."
"There was something more than a vice there," said Cook, thinking it over. "The vice didn't fire the rifle. Why why, now we begin to understand that hair-trigger pull!"
"You cast your mind back again, and see if there isn't another peculiar circumstance which you begin to understand," recommended Hemingway. "What's that?"
"Miss Fanshawe's dog didn't bark," said Hemingway. "And why not? Because there wasn't anyone there to bark at. Funny how simple things are as soon as you stop looking at them from the wrong angle!"
"I certainly think you're on to something," admitted Cook. "I suppose I ought to have been on to it myself."
"You? Why, it's taken me long enough!" said Hemingway. "I don't blame you for not spotting it. You got the gun, and there wasn't a ha'porth of reason why anyone should have tumbled to it that it wasn't fired by some bloke who dropped it, and made off."
"Well, it's very kind of you to say so, I'm sure," responded Cook, a little dubiously.
"I don't see that the case is solved, not by a long chalk," remarked the Sergeant. "It's all very well: and I grant you you've pieced it together a fair treat, sir, but what I want to know is, what is this mysterious gadget which set the rifle off just at the right moment?"
"What I want to know," said Hemingway, "isn't what is it, because we'll find that out all in good time, but where is it?"