"I did see, and I wasn't satisfied; but I didn't tell the inspector what I thought. It was clearer to me than ever that Guide had not committed the murder. What I asked the inspector was this: 'Had either of the men got any luggage in the carriage?'
"The inspector answered, with a laugh, 'Not quite, Mr. Grayson, or you would see it here.'
"Then I took on paper a rough outline of that fragment of bone, and an accurate sketch of exact size of the gash in it, and the inspector went away. One thing his visit had shown me. Andrew Walker was not slain by a blow from behind by the pickaxe.
"I met Barnes whilst I was nibbling lunch, and told him this. He heard me doubtfully. 'You may be right,' said he, 'but I'm bothered if I see what you have to go upon.'
"'You know what a pickaxe is like?' I said.
"'Certainly.'
"'A cross-section of one of the blades would be what?'
"'Square—or perhaps oblong.'
"'Quite so. Rectangular. What I want to get at is this: it wouldn't even be diamond shape, with the angles obtuse and acute alternately.'
"'Certainly not. The angles would be clean right-angles.'