"To begin with, there was the railway carriage; but a little thought showed me that nothing was to be done there. The compartment would have been inspected by the police, and then swept and cleaned and garnished, and coupled on to its train once more, and used by unconscious passengers for weeks since the uproar occurred in it.
"All that I had got to go upon were the notes and relics held at Scotland Yard.
"The police authorities were very good. Of course, they were keen enough to bring off the prosecution with professional éclat; but they were not exactly anxious to hand over a poor wretch to the hangman if he was not thoroughly deserving of a dance on nothing. They placed at my disposal every scrap of their evidence, and said that they thought the reading of it all was plain beyond dispute. I thought so, too, at first. They sent an inspector to my chambers as their envoy.
"On one point, though, after a lot of thought, I did not quite agree with them. I held a grisly relic in my hand, gazing at it fixedly. It was a portion of Walker's skull—a disc of dry bone with a splintered aperture in the middle.
"'And so you think the pickaxe made that hole,' I said to the inspector.
"'YOU THINK THE PICKAXE MADE THAT HOLE,' I SAID TO THE INSPECTOR."
"'I don't think there can be any doubt about it, Mr Grayson. Nothing else could have done it, and the point of the pick was smeared with blood.'
"'But would there be room to swing such a weapon in a third-class Metropolitan railway carriage?'
"'We thought of that, and at first it seemed a poser. The roof is low, and both Guide and Walker are tall men; but if Guide had gripped the shaft by the end, so, with his right hand pretty near against the head, so, he'd have had heaps of room to drive it with a sideways swing. I tried the thing for myself; it acted perfectly. Here's the pickaxe: you can see for yourself.'