The Blue Scarab/A Fisher of Men

HE 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.

"Item one: a small leather dressing-wallet. Rather shabby, but originally of excellent quality. It contains two Swedish razors, a little Washita hone, a diminutive strop, a folding shaving-brush, which is slightly damp to the fingers and has a scent similar to that of the stick of shaving soap. You notice that the hone is distinctly concave in the middle and that the inscription on the razors, 'Arensburg, Eskilstuna, Sweden,' is partly ground away. Then there is a box containing a very dry cake of soap, a little manicure set, a well-worn toothbrush, a nailbrush, dental-brush, button-hook, corn-razor, a small clothes-brush and a pair of small hairbrushes. It seems to me, Badger, that this wallet suggests—mind, I only say 'suggests'—a pretty complete answer to one of your questions."

"I don't see how," said the inspector. "Tell me what it suggests to you."

"It suggests to me," replied Thorndyke, laying down the lens through which he had been inspecting the hair-brushes, "a middle-aged or elderly man with a shaven upper lip and a beard; a well-preserved, healthy man, neat, orderly, provident and careful as to his appearance; a man long habituated to travelling, and—though I don't insist on this, but the appearances suggest that he had been living for some time in a particular households and that at the time when he lost the bag, he was changing his residence."

"He was that," cackled the inspector, "if the constable's account of the way he went over that wall is to be trusted. But still, I don't see how you have arrived at all those facts."

"Not facts, Badger," Thorndyke corrected. "I said suggestions. And those suggestions may be quite misleading. There may be some factor, such as change of ownership of the wallet, which we have not allowed for. But, taking the appearances at their face value, that is what they suggest. There is the wallet itself, for instance—strong, durable, but shabby with years of wear. And observe that it is a travelling-wallet and would be subjected to wear only during travel. Then further, as to the time factor, there are the hone and the razors. It takes a good many years to wear a Washita hone hollow or to wear away the blade of a Swedish razor until the maker's mark is encroached on. The state of health, and to some extent the age, are suggested by the toothbrush and the dental-brush. He has lost some teeth, since he wears a plate, but not many; and he is free from pyorrhoea and alveolar absorption. You don't wear a toothbrush down like this on half a dozen rickety survivors. But a man whose teeth will bear hard brushing is probably well-preserved and healthy."

"You say that he shaves his upper lip but wears a beard," said the inspector. "How do you arrive at that?"

"It is fairly obvious," replied Thorndyke. "We see that he has razors and uses them, and we also see that he has a beard."

"Do we?" exclaimed Badger. "How do we?"

Thorndyke delicately picked a hair from one of the hairbrushes and held it up. "That is not a scalp hair," said he. "I should say that it came from the side of the chin."

Badger regarded the hair with evident disfavour. "Looks to me," he remarked, "as if a small tooth-comb might have been useful."

"It does," Thorndyke agreed, "but the appearance is deceptive. This is what is called a moniliform hair—like a string of beads. But the bead-like swellings are really parts of the hair. It is a diseased, or perhaps we should say an abnormal, condition." He handed me the hair together with his lens, through which I examined it and easily recognised the characteristic swellings.

"Yes," said I, "it is an early case of trichorrexis nodosa."

"Good Lord!" murmured the inspector. "Sounds like a Russian nobleman. Is it a common complaint?

"It is not a rare disease—if you can call it a disease," I replied, "but it is a rare condition, taking the population as a whole."

"It is rather a remarkable coincidence that it should happen to occur in this particular case," the superintendent observed.

"My dear Miller," exclaimed Thorndyke, "surely your experience must have impressed on you the astonishing frequency of the unusual and the utter failure of the mathematical laws of probability in practice. Believe me, Miller, the bread-and-butterfly was right. It is the exceptional that always happens."

Having discharged this paradox, he once more dived into the bag, and this time handed out a singular and rather unsavoury-looking parcel, the outer investment of which was formed by what looked like an excessively dirty towel, but which, as Thorndyke delicately unrolled it, was seen to be only half a towel which was supplemented by a still dirtier and excessively ragged coloured handkerchief. This, too, being opened out, disclosed an extremely soiled and rather frayed collar (which, like the other articles, bore no name or mark), and a mass of grass, evidently used as packing material.

The inspector picked up the collar and quoted reflectively, "He is a man, neat, orderly and careful as to his appearance," after which he dropped the collar and ostentatiously wiped his fingers.

Thorndyke smiled grimly but refrained from repartee as he carefully separated the grass from the contained objects, which turned out to be a small telescopic jemmy, a jointed auger, a screwdriver and a bunch of skeleton keys.

"One understands his unwillingness to encounter the constable with these rather significant objects in his possession," Thorndyke remarked. "They would have been difficult to explain away." He took up the heap of grass between his hands and gently compressed it to test its freshness. As he did so a tiny, cigar-shaped object dropped on the paper.

"What is that?" asked the superintendent. "It looks like a chrysalis."

"It isn't," said Thorndyke. "It is a shell, a species of Clausilia, I think." He picked up the little shell and closely examined its mouth through his lens. "Yes," he continued, "it is a Clausilia. Do you study our British mollusca, Badger?"

"No, I don't," the inspector replied with emphasis.

"Pity," murmured Thorndyke. "If you did, you would be interested to learn that the name of this little shell is Clausilia biplicata."

"I don't care what its beastly name is," said Badger. "I want to know whose bag this is; what the owner is like; and where he came from and where he has gone to. Can you tell us that?"

Thorndyke regarded the inspector with wooden gravity. "It is all very obvious," said he, "very obvious. But still, I think I should like to fill in a few details before making a definite statement. Yes, I think I will reserve my judgment until I have considered the matter a little further."

The inspector received this statement with a dubious grin. He was in somewhat of a dilemma. My colleague was addicted to a certain dry facetiousness, and was probably pulling the inspector's leg. But, on the other hand, I knew, and so did both the detectives, that it was perfectly conceivable that he had actually solved Badger's problem, impossible as it seemed, and was holding back his knowledge until he had seen whither it led.

"Shall we take a glance at the stick?" said he, picking it up as he spoke and running his eye over its not very distinctive features. It was a common ash stick, with a crooked handle polished and darkened by prolonged contact with an apparently ungloved hand, and it was smeared for about three inches from the tip with a yellowish mud. The iron shoe of the ferrule was completely worn away and the deficiency had been made good by driving a steel boot-stud into the exposed end.

"A thrifty gentleman, this," Thorndyke remarked, pointing to the stud as he measured the diameter of the ferrule with his pocket calliper-gauge. "Twenty-three thirty-seconds is the diameter," he added, looking gravely at the inspector. "You had better make a note of that, Badger."

The inspector smiled sourly as Thorndyke laid down the stick, and once more picking up the little green canvas case that contained his research outfit, prepared to depart.

"You will hear from us, Miller," he said, "if we pick up anything that will be useful to you. And now, Jervis, we must really take ourselves off."

As the tinkling hansom bore us down Whitehall towards Waterloo, I remarked, "Badger half suspects you of having withheld from him some valuable information in respect of that bag."

"He does," Thorndyke agreed with a mischievous smile; "and he doesn't in the least suspect me of having given him a most illuminating hint."

"But did you?" I asked, rapidly reviewing the conversation and deciding that the facts elicited from the dressing-wallet could hardly be described as hints.

"My learned friend," he replied, "is pleased to counterfeit obtuseness. It won't do, Jervis. I've known you too long."

I grinned with vexation. Evidently I had missed the point of a subtle demonstration, and I knew that it was useless to ask further questions; and for the remainder of our journey, in the cab I struggled vainly to recover the "illuminating hint" that the detectives—and I—had failed to note. Indeed, so preoccupied was I with this problem that I rather overlooked the fact that the jettisoned bag was really no concern of ours, and that we were actually engaged in the investigation of a crime of which, at present, I knew practically nothing. It was not until we had secured an empty compartment and the train had begun to move that this suddenly dawned on me; whereupon I dismissed the bag problem and applied to Thorndyke for details of the "Brentford Train Mystery."

"To call it a mystery," said he, "is a misuse of words. It appears to be a simple train robbery. The identity of the robber is unknown, but there is nothing very mysterious in that; and the crime otherwise is quite commonplace. The circumstances are these: Some time ago, Mr. Lionel Montague, of the firm, Lyons, Montague & Salaman, art dealers, bought from a Russian nobleman a very valuable diamond necklace and pendant. The peculiarity of this necklace was that the stones were all of a pale blue colour and pretty accurately matched, so that in addition to the aggregate value of the stones—which were all of large size and some very large—was the value of the piece as a whole due to this uniformity of colour. Mr. Montague gave £70,000 for it, and considered that he had made an excellent bargain. I should mention that Montague was the chief buyer for the firm, and that he spent most of his time travelling about the Continent in search of works of art and other objects suitable for the purposes of his firm, and that, naturally, he was an excellent judge of such things. Now, it seems that he was not satisfied with the settings of this necklace, and as soon as he had purchased it he handed it over to Messrs. Binks, of Old Bond Street, to have the settings replaced by others of better design. Yesterday morning he was notified by Binks that the resetting was completed, and in the afternoon he called to inspect the work and take the necklace away if it was satisfactory. The interview between Binks and Montague took place in a room behind the shop, but it appears that Montague came out into the shop to get a better light for his inspection and Mr. Binks states that as his customer stood facing the door, examining the new settings, he, Binks, noticed a man standing by the doorway furtively watching Mr. Montague."

"There is nothing very remarkable in that," said I. "If a man stands at a shop door with a necklace of blue diamonds in his hand, he is rather likely to attract attention."

"Yes," Thorndyke agreed. "But the significance of an antecedent is apt to be more appreciated after the consequences have developed. Binks is now very emphatic about the furtive watcher. However, to continue: Mr. Montague, being satisfied with the new settings, replaced the necklace in its case, put the latter into his bag—which he had brought with him from the inner room—and a minute or so later left the shop. That was about 5 p.m.; and he seems to have gone direct to the flat of his partner, Mr. Salaman, with whom he had been staying for a fortnight, at Queen's Gate. There he remained until about half-past eight, when he came out accompanied by Mr. Salaman. The latter carried a small suit-case, while Montague carried a handbag in which was the necklace. It is not known whether it contained anything else.

"From Queen's Gate the two men proceeded to Waterloo, walking part of the way and covering the remainder by omnibus."

"By omnibus!" I exclaimed, "with seventy thousand pounds of diamonds about them!"

"Yes, it sounds odd. But people who habitually handle portable property of great value seem to resemble those who habitually handle explosives. They gradually become unconscious of the risks. At any rate, that is how they went, and they arrived safely at Waterloo in time to catch the 9.15 train for Isleworth. Mr. Salaman saw his partner established in an empty first-class compartment and stayed with him, chatting, until the train started.

"Mr. Montague's destination was Isleworth, in which rather unlikely neighbourhood Mr. Jacob Lowenstein, late of Chicago, and now of Berkeley Square, has a sort of river-side villa with a motor boat-house attached. Lowenstein had secured the option of purchasing the blue diamond necklace, and Montague was taking it down to exhibit it and carry out the deal. He was proposing to stay a few days with Lowenstein, and then he was proceeding to Brussels on one of his periodic tours. But he never reached Isleworth. When the train stopped at Brentford, a porter noticed a suit-case on the luggage-rack of an apparently empty first-class compartment. He immediately entered to take possession of it, and was in the act of reaching up to the rack when his foot came in contact with something soft under the seat. Considerably startled, he stooped and peered under, when, to his horror, he perceived the body of a man, quite motionless and apparently dead. Instantly he darted out and rushed up the platform in a state of wild panic until he, fortunately, ran against the station master, with whom and another porter he returned to the compartment. When they drew the body out from under the seat it was found to be still breathing, and they proceeded at once to apply such restoratives as cold water and fresh air, pending the arrival of the police and the doctor, who had been sent for.

"In a few minutes the police arrived accompanied by the police surgeon, and the latter, after a brief examination, decided that the unconscious man was suffering from the effects of a large dose of chloroform, violently and unskilfully administered, and ordered him to be carefully removed to a local nursing home. Meanwhile, the police had been able, by inspecting the contents of his pockets, to identify him as Mr. Lionel Montague."

"The diamonds had vanished, of course?" said I.

"Yes. The handbag was not in the compartment, and later an empty handbag was picked up on the permanent way between Barnes and Chiswick, which seems to indicate the locality where the robbery took place."

"And what is our present objective?"

"We are going, on instructions from Mr. Salaman, to the nursing home to see what information we can pick up. If Montague has recovered sufficiently to give an account of the robbery, the police will have a description of the robber, and there may not be much for us to do. But you will have noticed that they do not seem to have any information at Scotland Yard at present, beyond what I have given you. So there is a chance yet that we may earn our fees."

Thorndyke's narrative of this somewhat commonplace crime, with the discussion which followed it, occupied us until the train stopped at Brentford Station. A few minutes later we halted in one of the quiet by-streets of this old-world town, at a soberly painted door on which was a brass plate inscribed "St. Agnes Nursing Home." Our arrival had apparently been observed, for the door was opened by a middle-aged lady in a nurse's uniform.

"Dr. Thorndyke?" she inquired; and as my colleague bowed assent she continued: "Mr. Salaman told me you would probably call. I am afraid I haven't very good news for you. The patient is still quite unconscious."

"That is rather remarkable," said Thorndyke.

"It is. Dr. Kingston, who is in charge of the case, is somewhat puzzled by this prolonged stupor. He is inclined to suspect a narcotic—possibly a large dose of morphine—in addition to the effects of the chloroform and the shock."

"He is probably right," said I; "and the marvel is that the man is alive at all after such outrageous treatment."

"Yes," Thorndyke agreed. "He must be pretty tough. Shall we be able to see him?"

"Oh, yes," the matron replied. "I am instructed to give you every assistance. Dr. Kingston would like to have your opinion on the case."

With this she conducted us to a pleasant room on the first floor, where, in a bed placed opposite a large window—left uncurtained—with the strong light falling full on his face, a man lay with closed eyes, breathing quietly and showing no sign of consciousness when we somewhat noisily entered the room. For some time Thorndyke stood by the bedside, looking down at the unconscious man, listening to the breathing and noting its frequency by his watch. Then he felt the pulse, and raising both eyelids, compared the two pupils.

"His condition doesn't appear alarming," was his conclusion. "The breathing is rather shallow, but it is quite regular, and the pulse is not bad though slow. The contracted pupils strongly suggest opium, or more probably morphine. But that could easily be settled by a chemical test. Do you notice the state of the face, Jervis?"

"You mean the chloroform burns? Yes, the handkerchief or pad must have been saturated. But I was also noticing that he corresponds quite remarkably with the description you were giving Badger of the owner of the dressing-wallet. He is about the age you mentioned—roughly about fifty—and he has the same old- fashioned treatment of the beard, the shaven upper lip and the monkey-fringe under the chin. It is rather an odd coincidence."

Thorndyke looked at me keenly. "The coincidence is closer than that, Jervis. Look at the beard itself."

He handed me his lens, and, stooping down, I brought it to bear on the patient's beard. And then I started back in astonishment; for by the bright light I could see plainly that a considerable proportion of the hairs were distinctly moniliform. This man's beard, too, was affected by an early stage of trichorrexis nodosa!

"Well!" I exclaimed, "this is really an amazing coincidence. I wonder if it is anything more."

"I wonder," said Thorndyke. "Are those Mr. Montague's things, Matron?"

"Yes," she replied, turning to the side table on which the patient's effects were neatly arranged. "Those are his clothes and the things which were taken from his pockets, and that is his bag. It was found on the line and sent on here a couple of hours ago. There is nothing in it."

Thorndyke looked over the various objects—keys, card-case, pocket-book, etc.—that had been turned out of the patient's pockets, and then picked up the bag, which he turned over curiously and then opened to inspect the interior. There was nothing distinctive about it. It was just a plain, imitation leather bag, fairly new, though rather the worse for its late vicissitudes, lined with coarse linen to which two large, wash-leather pockets had been roughly stitched. As he laid the bag down and picked up his own canvas case, he asked: "What time did Mr. Salaman come to see the patient?"

"He came here about ten o'clock this morning, and he was not able to stay more than half an hour as he had an appointment. But he said he would look in again this evening. You can't stay to see him, I suppose?"

"I'm afraid not," Thorndyke replied; "in fact we must be off now, for both Dr. Jervis and I have some other matters to attend to."

"Are you going straight back to the chambers, Jervis?" Thorndyke asked, as we walked down the main street towards the station.

"Yes," I replied in some surprise. "Aren't you?"

"No. I have a little expedition in view."

"Oh, have you?" I exclaimed, and as I spoke it began to dawn on me that I had overestimated the importance of my other business.

"Yes," said Thorndyke "the fact is that—ha! excuse me one moment, Jervis." He had halted abruptly outside a fishing-tackle shop and now, after a brief glance in through the window, entered with an air of business. I immediately bolted in after him, and was just in time to hear him demand a fishing-rod of a light and inexpensive character. When this had been supplied he asked for a line and one or two hooks; and I was a little surprised—and the vendor was positively scandalised—at his indifference to the quality or character of these appliances. I believe he would have accepted cod-line and a shark-hook if they had been offered.

"And now I want a float," said he.

The shopkeeper produced a tray containing a varied assortment of floats over which Thorndyke ran a critical eye, and finally reduced the shopman to stupefaction by selecting a gigantic, pot-bellied scarlet-and-green atrocity that looked like a juvenile telegraph buoy.

I could not let this outrage pass without comment. "You must excuse me, Thorndyke," I said, "if I venture to point out that the Greenland whale no longer frequents the upper reaches of the Thames."

"You mind your own business," he retorted, stolidly pocketing the telegraph buoy when he had paid for his purchases. "I like a float that you can see."

Here the shopman, recovering somewhat from the shock of surprise, remarked deferentially that it was a long time since a really large pike had been caught in the neighbourhood; whereupon Thorndyke finished him off by replying: "Yes, I've no doubt. They don't use the right sort of floats, you know. Now, when the pike see my float, they will just come tumbling over one another to get on the hook." With this he tucked the rod under his arm and strolled out, leaving the shopman breathing hard and staring harder.

"But what on earth," I asked, as we walked down the street (watched by the shopman who had come out on the pavement to see the last of us), "do you want with such an enormous float? Why, it will be visible a quarter of a mile away."

"Exactly," said Thorndyke. "And what more could a fisher of men require?"

This rejoinder gave me pause. Evidently Thorndyke had something in hand of more than common interest; and again it occurred to me that my own business engagements were of no special urgency. I was about to mention this fact when Thorndyke again halted—at an oilshop this time.

"I think I will step in here and get a little burnt umber," said he.

I followed him into the shop, and while the powder-colour was being weighed and made up into a little packet I reflected profoundly. Fishing-tackle and burnt umber had no obvious associations. I began to be mystified and correspondingly inquisitive.

"What do you want the burnt umber for?" I asked as soon as we were outside.

"To mix with plaster," he replied readily.

"But why do you want to colour the plaster? And what are you going to do with it?"

"Now, Jervis," he admonished with mock severity, "you are not doing yourself justice. An investigator of your experience shouldn't ask for explanations of the obvious."

"And why," I continued, "did you want to know if I was going straight back to the chambers?

"Because I may want some assistance later. Probably Polton will be able to do all that I want, but I wished to know that you would both be within reach of a telegram."

"But," I exclaimed, "what nonsense it is to talk of sending a telegram to me when I'm here!"

"But I may not want any assistance, after all."

"Well," I said doggedly, "you are going to have it whether you want it or not. You've got something on and I'm going to be in it."

"I like your enthusiasm, Jervis," he chuckled; "but it is quite possible that I shall merely find a mare's nest."

"Very well," said I. "Then I'll help you to find it. I've had plenty of experience in that line, to say nothing of my natural gifts. So lead on."

He led on, with a resigned smile, to the station, where we were fortunate enough to find a train just ready to start. But our journey was not a long one, for at Chiswick Thorndyke got out of the train, and on leaving the station struck out eastward with a very evident air of business. As we entered the outskirts of Hammersmith he turned into a by-street which presently brought us out into Bridge Road. Here he turned sharply to the right and, at the same brisk pace, crossed Hammersmith Bridge and made his way to the towing path. As he now slowed down perceptibly, I ventured to inquire whether this was the spot on which he proposed to exhibit his super-float.

"This, I think, will be our fishing-ground," he replied; "but we will look over it carefully and select a suitable pitch."

He continued to advance at an easy pace, and I noticed that, according to his constant habit, he was studying the peculiarities of the various feet that had trodden the path within the last day or two, keeping, for this purpose on the right-hand side, where the shade of a few pollard willows overhanging an indistinct dry ditch had kept the ground soft. We had walked on for nearly half a mile when he halted and looked round.

"I think we had better turn back a little way," said he. "We seem to have overshot our mark."

I made no comment on this rather mysterious observation, and we retraced our steps for a couple of hundred yards, Thorndyke still walking on the side farthest from the river and still keeping his eyes fixed on the ground. Presently he again halted, and looking up and down the path, of which we were at the moment the only occupants, placed the canvas case on the ground and unfastened its clasps.

"This, I think, will be our pitch," said he.

"What are you going to do?" I asked.

"I am going to make one or two casts. And meanwhile you had better get the fishing-rod fixed together so as to divert the attention of any passers-by."

I proceeded to make ready the fishing-tackle, but at the same time kept a close watch on my colleague's proceedings. And very curious proceedings they were. First he dipped up a little water from the river in the rubber mixing bowl with which he mixed a bowlful of plaster, and into this he stirred a few pinches of burnt umber, whereby its dazzling white was changed to a muddy buff. Then, having looked up and down the path, he stooped and carefully poured the plaster into a couple of impressions of a walking-stick that were visible at the edge of the path and finished up by filling a deep impression of the same stick, at the margin of the ditch, where it had apparently been stuck in the soft, clayey ground.

As I watched this operation, a sudden suspicion flashed into my mind. Dropping the fishing-rod, I walked quickly along the path until I was able to pick up another impression of the stick. A very brief examination of it confirmed my suspicion. At the centre of the little shallow pit was a semicircular impression—clearly that of a half-worn boot-stud.

"Why!" I exclaimed, "this is the stick that we saw at Scotland Yard!"

"I should expect it to be and I believe it is," said Thorndyke. "But we shall be better able to judge from the casts. Pick up your rod. There are two men coming down the path."

He closed his "research-case" and drawing the fishing-line from his pocket, began meditatively to unwind it.

"I could wish," said I, "that our appearance was more in character with the part of the rustic angler; and for the Lord's sake keep the float out of sight, or we shall collect a crowd."

Thorndyke laughed softly. "The float," said he, "was intended for Polton. He would have loved it. And the crowd would have been rather an advantage—as you will appreciate when you come to use it."

The two men—builder's labourers, apparently—now passed us with a glance of faint interest at the fishing-tackle; and as they strolled by I appreciated the value of the burnt umber. If the casts bad been made of the snow-white plaster they would have stared conspicuously from the ground and these men would almost certainly have stopped to examine them and see what we were doing. But the tinted plaster was practically invisible.

"You are a wonderful man, Thorndyke," I said, as I announced my discovery. "You foresee everything."

He bowed his acknowledgments, and having tenderly felt one of the casts and ascertained that the plaster had set hard, he lifted it with infinite care, exhibiting a perfect facsimile of the end of the stick, on which the worn boot-stud was plainly visible, even to the remains of the pattern. Any doubt that might have remained as to the identity of the stick was removed when Thorndyke produced his calliper-gauge.

"Twenty-three thirty-seconds was the diameter, I think," said he as he opened the jaws of the gauge and consulted his notes. He placed the cast between the jaws, and as they were gently slid into contact, the index marked twenty-three thirty-seconds.

"Good," said Thorndyke, picking up the other two casts and establishing their identity with the one which we had examined. "This completes the first act." Dropping one cast into his case and throwing the other two into the river, he continued: "Now we proceed to the next and hope for a like success. You notice that he stuck his stick into the ground. Why do you suppose he did that?"

"Presumably to leave his hands free."

"Yes. And now let us sit down here and consider why he wanted his hands free. Just look around and tell me what you see."

I gazed rather hopelessly at the very undistinctive surroundings and began a bald catalogue. "I see a shabby-looking pollard willow, an assortment of suburban vegetation, an obsolete tin saucepan—unserviceable—and a bald spot where somebody seems to have pulled up a small patch of turf."

"Yes," said Thorndyke. "You will also notice a certain amount of dry, powdered earth distributed rather evenly over the bottom of the ditch. And your patch of turf was cut round with a large knife before it was pulled up. Why do you suppose it was pulled up?"

I shook my head. "It's of no use making mere guesses."

"Perhaps not," said he, "though the suggestion is fairly obvious when considered with the other appearances. Between the roots of the willow you notice a patch of grass that looks denser than one would expect from its position. I wonder"

As he spoke, he reached forward with his stick and prised vigorously at the edge of the patch, with the result that the clump of grass lifted bodily; and when I picked it up and tried it on the bald spot, the nicety with which it fitted left no doubt as to its origin.

"Ha!" I exclaimed, looking at the obviously disturbed earth between the roots of the willow, which the little patch of turf had covered; "the plot thickens. Something seems to have been either buried or dug up there; more probably buried."

"I hope and believe that my learned friend is correct," said Thorndyke, opening his case to abstract a large, powerful spatula.

"What do you expect to find there?" I asked.

"I have a faint hope of finding something wrapped in the half of a very dirty towel," was the reply.

"Then you had better find it quickly," said I, "for there is a man coming along the path from the Putney direction."

He looked round at the distant figure, and driving the spatula into the loose earth stirred it up vigorously.

"I can feel something," he said, digging away with powerful thrusts and scooping the earth out with his hands. Once more he looked round at the approaching stranger—who seemed now to have quickened his pace but was still four or five hundred yards distant. Then, thrusting his hands into the hole, he gave a smart pull. Slowly there came forth a package, about ten inches by six, enveloped in a portion of a peculiarly filthy towel and loosely secured with string. Thorndyke rapidly cast off the string and opened out the towel, disclosing a handsome morocco case with an engraved gold plate.

I pounced on the case and, pressing the catch, raised the lid; and though I had expected no less, it was with something like a shock of surprise that I looked on the glittering row and the dazzling cluster of steely-blue diamonds.

As I closed the casket and deposited it in the green canvas case, Thorndyke, after a single glance at the treasure and another along the path, crammed the towel into the hole and began to sweep the loose earth in on top of it. The approaching stranger was for the moment hidden from us by a bend of the path and a near clump of bushes, and Thorndyke was evidently working to hide all traces before he should appear. Having filled the hole, he carefully replaced the sod of turf and then, moving over to the little bare patch from whence the turf had been removed, he began swiftly to dig it up.

"There," said he, flinging on the path a worm which he had just disinterred, "that will explain our activities. You had better continue the excavation with your pocket knife, and then proceed to the capture of the leviathans. I must run up to the police station and you must keep possession of this pitch. Don't move away from here on any account until I come back or send somebody to relieve you. I will hand you over the float; you'll want that." With a malicious smile he dropped the gaudy monstrosity on the path, and having wiped the spatula and replaced it in the case, picked up the latter and moved away towards Putney.

At this moment the stranger reappeared, walking as if for a wager, and I began to peck up the earth with my pocket-knife.

As the man approached he slowed down by degrees until he came up at something like a saunter. He was followed at a little distance by Thorndyke, who had turned as if he had changed his mind, and now passed me with the remark that "Perhaps Hammersmith would be better." The stranger cast a suspicious glance at him and then turned his attention to me.

"Lookin' for worms?" he inquired, halting and surveying me inquisitively.

I replied by picking one up (with secret distaste) and holding it aloft, and he continued, looking wistfully at Thorndyke's retreating figure:

"Your pal seems to have had enough."

"He hadn't got a rod," said I; "but he'll be back presently."

"Ah!" said he, looking steadily over my shoulder in the direction of the willow. "Well, you won't do any good here. The place where they rises is a quarter of a mile farther down—just round the bend there. That's a prime pitch. You just come along with me and I'll show you."

"I must stay here until my friend comes back," said I. "But I'll tell him what you say."

With this I seated myself stolidly on the bank and, having flung the baited hook into the stream, sat and glared fixedly at the preposterous float. My acquaintance fidgeted about me uneasily, endeavouring from time to time to lure me away to the "prime pitch" round the bend. And so the time dragged on until three-quarters of an hour had passed.

Suddenly I observed two taxicabs crossing the bridge, followed by three cyclists. A minute or two later Thorndyke reappeared, accompanied by two other men, and then the cyclists came into view, approaching at a rapid pace.

"Seems to be a regular procession," my friend remarked, viewing the new arrivals with evident uneasiness. As he spoke, one of the cyclists halted and dismounted to examine his tyre, while the other two approached and shot past us. Then they, too, halted and dismounted, and having deposited their machines in the ditch, they came back towards us. By this time I was able—with a good deal of surprise—to identify Thorndyke's two companions as Inspector Badger and Superintendent Miller. Perhaps my acquaintance also recognised them, or possibly the proceedings of the third cyclist—who had also laid down his machine and was approaching on foot—disturbed him. At any rate he glanced quickly from the one group to the other and, selecting the smaller one, sprang suddenly between the two cyclists and sped away along the path like a hare.

In a moment there was a wild stampede. The three cyclists, remounting their machines, pedalled furiously after the fugitive, followed by Badger and Miller on foot. Then the fugitive, the cyclists, and finally the two officers disappeared round the bend of the path.

"How did you know that he was the man?" I asked, when my colleague and I were left alone.

"I didn't, though I had pretty strong grounds for suspicion. But I merely brought the police to set a watch on the place and arrange an ambush. Their encircling movement was just an experimental bluff; they might have been chary of arresting the fellow if he hadn't taken fright and bolted. We have been fortunate all round, for, by a lucky chance, Badger and Miller were at Chiswick making inquiries and I was able to telephone to them to meet me at the bridge."

At this moment the procession reappeared, advancing briskly; and my late adviser marched at the centre securely handcuffed. As he was conducted past me he glared savagely and made some impolite references to a "blooming nark."

"You can take him in one of the taxis," said Miller, "and put your bicycles on top." Then, as the procession moved on towards the bridge he turned to Thorndyke. "I suppose he's the right man, doctor, but he hasn't got any of the stuff on him."

"Of course he hasn't," said Thorndyke.

"Well, do you know where it is?"

Thorndyke opened his case and taking out the casket, handed it to the superintendent. "I shall want a receipt for it," said he.

Miller opened the casket, and at the sight of the glittering jewels both the detectives uttered an exclamation of amazement, and the superintendent demanded: "Where did you get this, sir?

"I dug it up at the foot of that willow."

"But how did you know it was there?"

"I didn't," replied Thorndyke; "but I thought I might as well look, you know," and he bestowed a smile of exasperating blandness on the astonished officer.

The two detectives gazed at Thorndyke, then they looked at one another and then they looked at me; and Badger observed, with profound conviction, that it was a "knock-out." "I believe the doctor keeps a tame clairvoyant," he added.

"And may I take it, sir," said Miller, "that you can establish a prima facie case against this man, so that we can get a remand until Mr. Montague is well enough to identify him?"

"You may," Thorndyke replied. "Let me know when and where he is to be charged and I will attend and give evidence."

On this Miller wrote out a receipt for the jewels and the two officers hurried off to their taxicab, leaving us, as Badger put it, "to our fishing."

As soon as they were out of sight, Thorndyke opened his case and mixed another bowlful of plaster. "We want two more casts," said he; "one of the right foot of the man who buried the jewels and one of the right foot of the prisoner. They are obviously identical, as you can see by the arrangement of the nails and the shape of the new patch on the sole. I shall put the casts in evidence and compare them with the prisoner's right boot."

I understood now why Thorndyke had walked away towards Putney and then returned in rear of the stranger. He had suspected the man and had wanted to get a look at his footprints. But there was a good deal in this case that I did not understand at all.

"There," said Thorndyke, as he deposited the casts, each with its pencilled identification, in his canvas case, "that is the end of the Blue Diamond Mystery."

"I beg your pardon," said I, "but it isn't. I want a full explanation. It is evident that from the house at Brentford you made a bee line to that willow. You knew then pretty exactly where the necklace was hidden. For all I know, you may have had that knowledge when we left Scotland Yard."

"As a matter of fact, I had," he replied. "I went to Brentford principally to verify the ownership of the wallet and the bag."

"But what was it that directed you with such certainty to the Hammersmith towing-path?"

It was then that he made the observation that I have quoted at the beginning of this narrative.

"In this case," he continued, "a curious fact, well known to naturalists, acquired vital evidential importance. It associated a bag, found in one locality, with another apparently unrelated locality. It was the link that joined up the two ends of a broken chain. I offered that fact to Inspector Badger, who, lacking the knowledge wherewith to interpret it, rejected it with scorn."

"I remember that you gave him the name of that little shell that dropped out of the handful of grass."

"Exactly," said Thorndyke. "That was the crucial fact. It told us where the handful of grass had been gathered."

"I can't imagine how," said I. "Surely you find shells all over the country?"

"That is, in general, quite true," he replied, "but Clausilia biplicata is one of the rare exceptions. There are four British species of these queer little univalves (which are so named from the little spring door with which the entrance of the shell is furnished): Clausilia laminata, Rolphii, rugosa and biplicata. The first three species have what we may call a normal distribution, whereas the distribution of biplicata is abnormal. This seems to be a dying species. It is in process of becoming extinct in this island. But when a species of animal or plant becomes extinct, it does not fade away evenly over the whole of its habitat, but it disappears in patches, which gradually extend, leaving, as it were, islands of survival. This is what has happened to Clausilia biplicata. It has disappeared from this country with the exception of two localities; one of these is in Wiltshire, and the other is the right bank of the Thames at Hammersmith. And this latter locality is extraordinarily restricted. Walk down a few hundred yards towards Putney, and you have walked out of its domain; walk up a few hundred yards towards the bridge, and again you have walked out of its territory. Yet within that little area it is fairly plentiful. If you know where to look—it lives on the bark or at the roots of willow trees—you can usually find one or two specimens. Thus, you see, the presence of that shell associated the handful of grass with a certain willow tree, and that willow was either in Wiltshire or by the Hammersmith towing-path. But there was nothing otherwise to connect it with Wiltshire, whereas there was something to connect it with Hammersmith. Let us for a moment dismiss the shell and consider the other suggestions offered by the bag and stick.

"The bag, as you saw, contained traces of two very different persons. One was a middle-class man, probably middle-aged or elderly, cleanly, careful as to his appearance and of orderly habits; the other, uncleanly, slovenly and apparently a professional criminal. The bag itself seemed to appertain to the former person. It was an expensive bag and showed signs of years of careful use. This, and the circumstances in which it was found, led us to suspect that it was a stolen bag. Now, we knew that the contents of a bag had been stolen. We knew that an empty bag had been picked up on the line between Barnes and Chiswick, and it was probable that the thief had left the train at the latter station. The empty bag had been assumed to be Mr. Montague's, whereas the probabilities—as for instance, the fact of its having been thrown out on the line—suggested that it was the thief's bag, and that Mr. Montague's had been taken away with its contents.

"The point, then, that we had to settle when we left Scotland Yard was whether this apparently stolen bag had any connection with the train robbery. But as soon as we saw Mr. Montague it was evident that he corresponded exactly with the owner of the dressing-wallet; and when we saw the bag that had been found on the line—a shoddy, imitation leather bag—it was practically certain that it was not his, while the roughly-stitched leather pockets, exactly suited to the dimensions of house-breaking tools, strongly suggested that it was a burglar's bag. But if this were so, then Mr. Montague's bag had been stolen, and the robber's effects stuffed into it.

"With this working hypothesis we were now able to take up the case from the other end. The Scotland Yard bag was Montague's bag. It had been taken from Chiswick to the Hammersmith towpath, where—judging from the clay smears on the bottom—it had been laid on the ground, presumably close to a willow tree. The use of the grass as packing suggested that something had been removed from the bag at this place—something that had wedged the tools together and prevented them from rattling; and there appeared to be half a towel missing. Clearly, the towpath was our next field of exploration.

"But, small as this area was geographically, it would have taken a long time to examine in detail. Here, however, the stick gave us invaluable aid. It had a perfectly distinctive tip, and it showed traces of having been stuck about three inches into earth similar to that on the bag. What we had thus to look for was a hole in the ground about three inches deep, and having at the bottom the impression of a half-worn boot-stud. This hole would probably be close to a willow.

"The search turned out even easier than I had hoped. Directly we reached the towpath I picked up the track of the stick, and not one track only, but a double track, showing that our friend had returned to the bridge. All that remained was to follow the track until it came to an end and there we were pretty certain to find the hole in the ground, as, in fact, we did."

"And why," I asked, "do you suppose he buried the stuff?"

"Probably as a precaution, in case he had been seen and described. This morning's papers will have told him that he had not been. Probably, also, he wanted to make arrangements with a fence and didn't want to have the booty about him."

There is little more to tell. When the case was heard on the following morning, Thorndyke's uncannily precise and detailed description of the course of events, coupled with the production of the stolen property, so unnerved the prisoner that he pleaded guilty forthwith.

As to Mr. Montague, he recovered completely in a few days, and a handsome pair of Georgian silver candlesticks may even to this day be seen on our mantelpiece testifying to his gratitude and appreciation of Thorndyke's brilliant conduct of the case.