she had a grievance against him; she is left-handed, and you remember that the murder was committed by a left-handed person.”
“Anything else?”
“Yes. I have seen those Italians, and the whole thing was a put-up job. A woman, in a widow’s dress and veil, paid them to go and play the fool outside the building, and she gave them the letter that was left with the porter. They haven’t identified her yet, but she seems to agree in size with Miss Curtis.”
“And how did she get out of the chambers, with the door bolted on the inside?”
“Ah, there you are! That’s a mystery at present—unless you can give us an explanation.” The inspector made this qualification with a faint grin, and added: “As there was no one in the place when we broke into it, the murderer must have got out somehow. You can’t deny that.”
“I do deny it, nevertheless,” said Thorndyke. “You look surprised,” he continued (which was undoubtedly true), “but yet the whole thing is exceedingly obvious. The explanation struck me directly I looked at the body. There was evidently no practicable exit from the flat, and there was certainly no one in it when you entered. Clearly, then, the murderer had never been in the place at all.”
“I don’t follow you in the least,” said the inspector.
“Well,” said Thorndyke, “as I have finished with the case, and am handing it over to you, I will put the evidence before you seriatim. Now, I think we are agreed that, at the moment when the blow was struck, the deceased was standing before the fireplace, winding the clock. The dagger entered obliquely from the left, and, if you recall its position, you will remember that its hilt pointed directly towards an open window.”
“Which was forty feet from the ground.”
“Yes. And now we will consider the very peculiar character of the weapon with which the crime was committed.”
He had placed his hand upon the knob of a drawer, when we were interrupted by a knock at the door. I sprang up, and, opening it, admitted no less a person than the porter of Brackenhurst Chambers. The man looked somewhat surprised on recognizing our visitors, but advanced to Thorndyke, drawing a folded paper from his pocket.
“I’ve found the article you were looking for, sir,” said he, “and a rare hunt I had for it. It had stuck in the leaves of one of them shrubs.”
Thorndyke opened the packet, and, having glanced inside, laid it on the table.
“Thank you,” said he, pushing a sovereign across to the gratified official. “The inspector has your name, I think?”
“He have, sir,” replied the porter; and, pocketing his fee, he departed, beaming.
“To return to the dagger,” said Thorndyke, opening the drawer. “It was a very peculiar one, as I have said, and as you will see from this model, which is an exact duplicate.” Here he exhibited Polton’s production to the astonished detective. “You see that it is extraordinarily slender, and free from projections, and of unusual materials. You also see that it was obviously not made by an ordinary dagger-maker; that, in spite of the Italian word scrawled on it, there is plainly written all over it ‘British mechanic.’ The blade is made from a strip of common three-quarter-inch tool steel; the hilt is turned from an aluminium rod; and there is not a line of engraving on it that could not be produced in a lathe by any engineer’s apprentice. Even the boss at the top is mechanical, for it is just like an ordinary hexagon nut. Then, notice the dimensions, as shown on my drawing. The parts A and B, which just project beyond the blade, are exactly similar in diameter—and such exactness could hardly be accidental. They are each parts of a circle having a diameter of 10.9 millimetres—a dimension which happens, by a singular coincidence, to be exactly the calibre of the old Chassepôt rifle, specimens of which are now on sale at several shops in London. Here is one, for instance.”
He fetched the rifle that he had bought, from the corner in which it was standing, and, lifting the dagger by its point, slipped the hilt into the muzzle. When he let go, the dagger slid quietly down the barrel, until its hilt appeared in the open breech.
“Good God!” exclaimed Marchmont. “You don’t suggest that the dagger was shot from a gun?”
“I do, indeed; and you now see the reason for the aluminium hilt—to diminish the weight of the already heavy projectile—and also for this hexagonal boss on the end?”
“No, I do not,” said the inspector; “but I say that you are suggesting an impossibility.”
“Then,” replied Thorndyke, “I must explain and demonstrate. To begin with, this projectile had to travel point foremost; therefore it had to be made to spin—and it certainly was spinning when it entered the body, as the clothing and the wound showed us. Now, to make it spin, it had to be fired from a rifled barrel; but as the hilt would not engage in the rifling, it had to be fitted with something that would. That something was evidently a soft metal washer, which fitted on to this hexagon, and which would be pressed into the grooves of the rifling, and so spin the dagger, but would drop off as soon as the weapon left the barrel. Here is such a washer, which Polton has made for us.”
He laid on the table a metal disc, with a hexagonal hole through it.
“This is all very ingenious,” said the inspector, “but I say it is impossible and fantastic.”
“It certainly sounds rather improbable,” Marchmont agreed.
“We will see,” said Thorndyke. “Here is a makeshift cartridge of Polton’s manufacture, containing an eighth charge of smokeless powder for a 20-bore gun.”
He fitted the washer on to the boss of the dagger in the open breech of the rifle, pushed it into the barrel, inserted the cartridge, and closed the breech. Then, opening the office-door, he displayed a target of padded strawboard against the wall.
“The length of the two rooms,” said he, “gives us a distance of thirty-two feet. Will you shut the windows, Jervis?”
I complied, and he then pointed the rifle at the target. There was a dull report—much less loud than I had expected—and when we looked at the target, we saw the dagger driven in up to its hilt at the margin of the bull’s-eye.
“You see,” said Thorndyke, laying down the rifle, “that the thing is practicable. Now for the evidence as to the actual occurrence. First, on the original dagger there are linear scratches which exactly correspond with the grooves of the rifling. Then there is the fact that the dagger was certainly spinning from left to right—in the direction of the rifling, that is—when it entered the body. And then there is this, which, as you heard, the porter found in the garden.”
He opened the paper packet. In it lay a metal disc, perforated by a hexagonal hole. Stepping into the office, he picked up from the floor the washer that he had put on the dagger, and laid it on the paper beside the other. The two discs were identical in size, and the margin of each was indented with identical markings, corresponding to the rifling of the barrel.
The inspector gazed at the two discs in silence for a while; then, looking up at Thorndyke, he said:
“I give in, Doctor. You’re right, beyond all doubt; but how you came to think of it beats me into fits. The only question now is, Who fired the gun, and why wasn’t the report heard?”
“As to the latter,” said Thorndyke, “it is
