Up to the very moment that Paul Harley, who had withdrawn, rejoined us in the garden, Inspector Aylesbury had not grasped the significance of that candle burning upon the yew tree. He continued to stare at it as if hypnotized, and when my friend re-appeared, carrying a long ash staff and a sheet of cardboard, I could have laughed to witness the expression upon the Inspector’s face, had I not been too deeply impressed with that which underlay this strange business.  
Wessex, on the other hand, was watching my friend eagerly, as an earnest student in the class-room might watch a demonstration by some celebrated lecturer.
 
“You will notice,” said Paul Harley, “that I have had a number of boards laid down upon the ground yonder, near the sun-dial. They cover a spot where the turf has worn very thin. Now, this garden, because of its sunken position, is naturally damp. Perhaps, Wessex, you would take up these planks for me.”
 
Inspector Wessex obeyed, and Harley, laying the ash stick and cardboard upon the ground, directed the ray of an electric torch upon the spot uncovered.
 
“The footprints of Colonel Menendez!” he explained. “Here he turned from the tiled path. He advanced three paces in the direction of the sun-dial, you observe, then stood still, facing we may suppose, since this is the indication of the prints, in a southerly direction.”
 
“Straight toward the Guest House,” muttered Inspector Aylesbury.
 
“Roughly,” corrected Harley. “He was fronting in that direction, certainly, but his head may have been turned either to the right or to the left. You observe from the great depth of the toe-marks that on this spot he actually fell. Then, here”—he moved the light—“is the impression of his knee, and here again—”
 
He shone the white ray upon a discoloured patch of grass, and then returned the lamp to his pocket.
 
“I am going to make a hole in the turf,” he continued, “directly between these two footprints, which seem to indicate that the Colonel was standing in the military position of attention at the moment that he met his death.”
 
With the end of the ash stick, which was pointed, he proceeded to do this.
 
“Colonel Menendez,” he went on, “stood rather over six feet in his shoes. The stick which now stands upright in the turf measures six feet, from the chalk mark up to which I have buried it to the slot which I have cut in the top. Into this slot I now wedge my sheet of cardboard.”
 
As he placed the sheet of cardboard in the slot which he had indicated, I saw that a round hole was cut in it some six inches in diameter. We watched these proceedings in silence, then:
 
“If you will allow me to adjust the candle, gentlemen,” said Harley, “which has burned a little too low for my purpose, I shall proceed to the second part of this experiment.”
 
He walked up to the yew tree, and by means of bending the nail upward he raised the flame of the candle level with the base of the embedded bullet.
 
“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 Colon............