“By heavens!” cried Wessex, suddenly divining the object of these proceedings, “Mr. Harley, this is genius!” “Thank you, Wessex,” Harley replied, quietly, but nevertheless he was unable to hide his gratification. “You see my point?” “Certainly.” “In ten minutes we shall know the truth.” “Oh, I see,” muttered Inspector Aylesbury; “we shall know the truth, eh? If you ask me the truth, it’s this, that we are a set of lunatics.” “My dear Inspector Aylesbury,” said Harley, good humouredly, “surely you have grasped the lesson of experiment number one?” “Well,” admitted the other, “it’s funny, certainly. I mean, it wants a lot of explaining, but I can’t say I’m convinced.” “That’s a pity,” murmured Wessex, “because I am.” “You see, Inspector,” Harley continued, patiently, “the body of Colonel Menendez as it lay formed a straight line between the sun-dial and the hut in the garden of the Guest House. That is to say: a line drawn from the window of the hut to the sun-dial must have passed through the body. Very well. Such an imaginary line, if continued _beyond_ the sun-dial, would have terminated near the base of the _seventh yew_ tree. Accordingly, I naturally looked for the _bullet_ there. It was not there. But I found it, as you know, in the ninth tree. Therefore, the shot could not possibly have been fired from the Guest House, because the spot in the ninth yew where the bullet had lodged is not visible from the Guest House.” Inspector Aylesbury removed his cap and scratched his head vigorously. “In order that we may avoid waste of valuable time,” said Harley, finally, “let us take a hasty observation from here. As a matter of fact, I have done so already, as nearly as was possible, without employing this rough apparatus.” He knelt down beside the yew tree, lowering his head so that the candlelight shone upon the brown, eager face, and looked upward, over the top of the sun-dial and through the hole in the cardboard. “Yes,” he muttered, a note of rising excitement in his voice. “As I thought, as I thought. Come, gentlemen, let us hurry.” He walked rapidly out of the garden, and up the steps, whilst we followed dumb with wonder--or such at any rate was the cause of my own silence. In the hall Pedro was standing, a bunch of keys in his hand, and evidently expecting Harley. “Will you take us by the shortest way to the tower stairs?” my friend directed. “Yes, sir.” Doubting, wondering, scarcely knowing whether to be fearful or jubilant, I followed, along a carpeted corridor, and thence, a heavy, oaken door being unlocked, across a dusty and deserted apartment apparently intended for a drawing room. From this, through a second doorway we were led into a small, square, unfurnished room, which I knew must be situated in the base of the tower. Yet a third door was unlocked, and: “Here is the stair, sir,” said Pedro.