man," observed Thorndyke, "who would successfully practise the scientific detection of crime must take all knowledge for his province. There is no single fact which may not, in particular circumstances, acquire a high degree of evidential value; and in such circumstances success or failure is determined by the possession or non-possession of the knowledge wherewith to interpret the significance of that fact."
This obiter dictum was thrown off apropos of our investigation of the case rather magniloquently referred to in the press as "The Blue Diamond Mystery;" and more particularly of an incident which occurred in the office of our old friend, Superintendent Miller, at Scotland Yard. Thorndyke had called to verify the few facts which had been communicated to him, and having put away his notebook and picked up his green canvas-covered research-case, had risen to take his leave, when his glance fell on a couple of objects on a side-table—a leather handbag and a walking-stick, lashed together with string, to which was attached a descriptive label.
He regarded them for a few moments reflectively and then glanced at the superintendent.
"Derelicts?" he inquired, "or jetsam?"
"Jetsam," the superintendent replied, "literally jetsam—thrown overboard to lighten the ship."
Here Inspector Badger, who had been a party to the conference, looked up eagerly.
"Yes," he broke in. "Perhaps the doctor wouldn't mind having a look at them. It's quite a nice little problem, doctor, and entirely in your line."
"What is the problem?" asked Thorndyke.
"It's just this," said Badger. "Here is a bag. Now the question is, whose bag is it? What sort of person is the owner? Where did he come from and where has he gone to?"
Thorndyke chuckled. "That seems quite simple," said he. "A cursory inspection ought to dispose of trivial details like those. But how did you come by the bag?"
"The history of the derelicts," said Miller, "is this: About four o'clock this morning, a constable on duty in King's Road, Chelsea, saw a man walking on the opposite side of the road, carrying a hand-bag. There was nothing particularly suspicious in this, but still the constable thought he would cross and have a closer look at him. As he did so the man quickened his pace and, of course, the constable quickened his. Then the man broke into a run, and so did the constable, and a fine, stern chase started. Suddenly the man shot down a by-street, and as the constable turned the corner he saw his quarry turn into a sort of alley. Following him into this, and gaining on him perceptibly, he saw that the alley ended in a rather high wall. When the fugitive reached the wall he dropped his bag and stick and went over like a harlequin. The constable went over after him, but not like a harlequin—he wasn't dressed for the part. By the time he got over, into a large garden with a lot of fruit trees in it, my nabs had disappeared. He traced him by his footprints across the garden to another wall, and when he climbed over that he found himself in by-street. But there was no sign of our agile friend. The constable ran up and down the street to the next crossings, blowing his whistle, but of course it was no go. So he went back across the garden and secured the bag and stick, which were at once sent here for examination."
"And no arrest has been made?"
"Well," replied Miller with a faint grin, "a constable in Oakley Street who had heard the whistle arrested a man who was carrying a suspicious-looking object. But he turned out to be a cornet player coming home from the theatre."
"Good," said Thorndyke. "And now let us have a look at the bag, which I take it has already been examined?"
"Yes, we've been through it," replied Miller, "but everything has been put back as we found it."
Thorndyke picked up the bag and proceeded to make a systematic inspection of its exterior.
"A good bag," he commented; "quite an expensive one originally, though it has seen a good deal of service. You noticed the muddy marks on the bottom?"
"Yes," said Miller. "Those were probably made when he dropped the bag to jump over the wall."
"Possibly," said Thorndyke, "though they don't look like street mud. But we shall probably get more information from the contents." He opened the bag, and after a glance at its interior, spread out on the table a couple of sheets of foolscap from the stationery rack, on which he began methodically to deposit the contents of the bag, accompanying the process with a sort of running commentary on their obvious characteristics.