`Still, we mustn't overlook the possibility that the bolt might have been fired instead of being used as a dagger. That's improbable; it's almost insane, on the face of it. If a crossbow is what I think it is, then it's highly unlikely that the murderer went wandering about the Tower of London carrying any such complicated apparatus.
`A knife, or the blow of a blackjack in the fog, would have done just as well. And because of the fog — as you say,
General — it's impossible that a marksman could have seen his target very far: certainly not to put a bolt so cleanly through the heart. Finally, there's the hat.' He took it from under his arm. `For whatever purpose, the murderer wanted to set his hat on the dead man's head. I think I may take it for granted that Mr Driscoll wasn't wearing it when he came to the Tower?'
`Naturally not. The Spur Guard and the warder at, the Middle Tower, who saw him come in, said he was wearing a cloth cap?
`Which isn't here now,' the chief inspector said, thoughtfully.. `But tell me, General. You said that so many people are always passing through here. - how did they happen to notice Driscoll?'
`Because they knew him. At least, that warder had a nodding acquaintance with him; the guard, of course, is always changing. He's quite a frequent visitor. Dalrye has got him out of so many scrapes in the past that Driscoll came to count on him that was why, he was here to-day!' I see. Now, before we go into this matter of the weapon, there's something, I want to know…. To begin with, we must admit this: whether he was shot or stabbed, he was killed very close to these steps. The murderer couldn't walk about here, with all the warders present, carrying a dead body; these steps were made to order for concealment, and they were used. So let's assume the most improbable course. Let's assume (a) that he was shot with a crossbow; (b) that the force of the shot — and it was a very powerful one knocked him over this rail, or that the murderer later pushed him over and; (c) that subsequently the killer decorated him with Sir William's hat. You see? Then from where could that bolt have been fired?'
General Mason massaged his imperial. They were peering at the wall across the way, at the gate of the Bloody Tower just opposite, and the bulk of a higher round tower just beside it.
`Well,' said the general, `it could have been fired from anywhere. From this lane, east or west, on either side of Traitors' Gate. From under the gate of the Bloody Tower; that's the most likely direction — a straight line. But it's tommyrot. You can't go marching about here with a crossbow, as though it were a rifle. It couldn't be done.'
Hadley nodded placidly.
`I know it couldn't: But, as you say, that's the most likely direction. So what about windows, or the top of a wall? Where could you stand and shoot a bolt from some such place? I shouldn't have asked, but I can't see anything beyond outlines in this fog.'