“Evidently the intruder gained access here,” said Holmes, tapping the high brick wall behind the Midland Bank.
“Look carefully Watson, I opine these holes were made by metal studded clogs!”
“But where the Devil would a fellow get those?”
Holmes took out a magnifying glass and looked carefully at the marks.
“One and five eights between the studs Watson. Don’t you see – the Bridlington quartz mine!”
“Good Lord Holmes! But…?”
Before Holmes could reply, Sir Arthur Conan Doyle suffered a fatal heart attack and so this mystery remains the only one unsolved in the entire Sherlock Holmes canon…