It was even as the summoning guard had said, and the Secret Service Bureau was in a very active condition when Brainerd and myself arrived.

Already telephone messages were flying, or had flown, to the various districts, and at every gate, thanks to the almost perfect system instituted by Superintendent Bonfield, shrewd and keen-eyed men were on the alert for any and all suspicious personages, and woe to those whose descriptions were written down in the books of the secret service men. They must be able to give good account of themselves, or their liberty would be brief.

It was not difficult to guess why my friend and myself had been so promptly summoned, in spite of the fact that already more than three hundred men, trained detectives, from our own large cities and from abroad, were upon duty here.

It was because they were on duty, every man at his post, whatever that might be, and because Brainerd and myself—having newly arrived and being for the moment unoccupied—were both near and available. Because, too, we were specials, that is, not subject to routine orders.

The robbery had really been a large one, and a bold one.

A collection of gems, cut and uncut, belonging to a foreign exhibit, and placed almost in the centre of one of those great well-guarded buildings, must be, one would think, proof against attack. Carefully secured in their trays and boxes, shut and locked behind heavy plates of glass in bronzed iron frames, guarded by day by trusted employÉs always under the eye of manager or exhibitor, and by night by a guard of drilled watchmen, what collection could be safer?

Nevertheless, at night there sparkled in those crystal prisms a little silver leaf with slightly curved edges, holding what looked like a tiny heap of water-drops, congealed and sparkling, shot through by a winter sunbeam; several larger diamonds, uncut, but brilliant and of great value; some exquisite specimens of pink topaz, and one great limpid, gleaming emerald, the pride of the fine collection. This at night. In the morning—they were not.

We sat down, a small group, for we did not hold council in the outer office, nor with one superfluous member, and began to find or make for ourselves a starting-point.

The work had been done very deftly. One of the glass plates had been cut out close to the bronze frame, and the gems removed; but that was not the strange part of the affair. In their places counterfeit gems had been put, careful imitations of the originals, and the glass plate had been deftly put in its place again.

'Ah!' said the fussy and half-distracted little man who represented the great foreign house so neatly defrauded, 'Ah! if I had not come down this morning, not one othair would haf know. I am the one only expairt. See! I am praisant wen the plaice is un-cloase. I stant near, wen soomsing make a beeg chock'—he meant shock or jar—'ant richt town falls out the klass. Wen I haf zeen it, I go queek ant look at doze shems. Ach! I know it awal—'tis fawlze awal—effery stonzes!'

That was the story. They had found the glass cut, and false gems in place of the true.

When we had stemmed the tide of this foreign eloquence, which was not for some time, I asked:

'How many know of this?'

'Nopotty at all onlee——'

'Not more than half a dozen,' broke in the chief of the bureau. 'Of course it wouldn't do! These are not the things that we like to let the public into. It wouldn't harmonize.'

'Ah-h-h!' aspirated the little man. 'It would trive away awal the tiamont mershants togetheer! U-u-og!'

'Right you are,' murmured Dave; and then in a louder tone, 'Can you trust your people to keep silent?'

'Ah! neffear fe-ur; tay know it is for tare goo-et.'

'Where are they?'

'The attendants?' queried the captain. 'Two are in charge of the pavilion, which remains closed. Lausch here was very clever; he sent for me at once, meantime keeping everything under cover; and when I saw how the land lay, I ordered close mouths all around, and put up a card "Closed for repairs." Then I sent for you, and we came back here. Of course you will want to see the place.'

'The place and the people,' I said, somewhat impatiently; 'and we can't get it over too quick.'

We spent three of the long morning hours in viewing, first the case where the real gems had been, and next the shams that had taken their place; then the surroundings, and last, and one by one, the people engaged about the Lausch pavilion. They were all Viennese, speaking the English language fairly well, far better than Mr. Lausch himself; and after we had questioned them closely and carefully, we closeted ourselves together and discussed the few 'points' so far gathered, if points, upon investigation, they proved to be.

'Carl,' chuckled my friend when we were at last alone, 'one of our missions here at the great Columbian Exposition was to hunt diamond thieves—eh!'

Of course his meaning was plain to me, but I chose to differ with him; there was no better way of rousing his wits.

'Of all the expert thieves on the two continents, the only ones who will not come here will be those whose faces are in every rogues' gallery in the land,' I replied. 'It would be too much good luck to find Bob and Delbras mixed up in this deal.'

'And yet,' declared he, 'I am willing to wager that it's the work of Delbras et al. Who but he would have prepared himself with a full assortment of paste jewels. Honestly, old man, don't you agree with me?'

'Yesterday,' I replied, 'I was ready to swear that Greenback Bob and his friend Delbras were circulating, perhaps issuing, those two-dollar Government notes.'

'And what's to hinder you thinking so still, eh?'

'Only that it would be too much of a fairy story to find our work cut out for us in such a way.'

Dave threw one sturdy leg across the chair nearest him, and settled himself in his favourite attitude for an argumentative discourse.

'Young man,' he began, 'if you can find anything connected with this White City that has sprung out of the lake and the prairie that has not a touch of the Arabian Nights about it, I want to know where it is. Can you show me anything more fairylike than this fairy city, built, as it has been, in the teeth of time?'

'Oh——'

'I tell you it's all a miracle, a nineteenth-century miracle! To come down to facts, now, you and I came here expecting to find Greenback Bob, didn't we?'

'Yes, of course.'

'And we have good reason to believe that Delbras is also here. Not much miracle about that, you'll admit.'

'No,' I assented, knowing that he must reach his climax in his own way.

'No; I should say so! But here is a miracle, a regular White City miracle. I wonder if Delbras and company know that—leaving a couple of thousand of blue-coated Columbian guards out of the question, and they're bright fellows, let me tell you—there are here three hundred and odd picked detectives, a squad at every gate, and every gate and every district connected by telephone with the main office here. Let a suspicious character appear, click goes the nearest telephone, sending the man's description to headquarters, and then, click, click, click, to every district, every gate, every man, goes this same description. Oh, the crooks whose faces are known will find a warm welcome here! It's only the fine workers, who have been so successful that they are not well known, who can make hay in this place.'

'All the same,' I here submitted, 'for such fellows as Delbras and his ilk, who know the world on both continents, this is a promising field, in spite of the telephone system and the detectives in plain clothes at every gate.'

'As how?'

'To the man who can speak several tongues, and is an adept at disguise, this Fair, with its citizens from every clime, will be a better place for concealment than London, Paris, and New York rolled into one.'

Dave gave utterance to a long, low whistle, and jerked himself to an upright position.

'You're right again!' he cried. 'Come, let's get down to business. What's your idea about this robbery?'

'About the same as yours, I fancy.'

'And what's that?'

I took out my notebook, wherein I had jotted down the most important items of testimony elicited from the Lausch attendants, saying:

'Get out your notes, Dave; let's see how they agree.' Dave produced his own briefer notes, and I began running my finger slowly down the pages.

'It was done during the day.'

'Of course!' impatiently.

'And slowly—that is, a little at a time.'

'How slowly?'

'Well, for instance, Lausch himself told of a young woman who was much taken with the pink topaz display—you remember?'

'Yes;' beginning to smile behind his book.

'He said that she wore a coat with a deep cape, and that she rested one arm upon the case.'

'Well, I did wonder what the woman's dress had to do with it. 'Gad, but you questioned those people until I began to feel sorry for them. What figure, now, is the dress likely to cut?'

I laughed.

'In this case let us suppose that the young woman is one of the gang.'

'Oh!'

'And let us fancy that while she peered at the pink topaz—you remember Lausch told us that she excused her nearness by saying that she was very near-sighted?'

'That's so.'

'Well, while looking at the gems, with her face bent over the case, one arm upon the edge, and with the voluminous cape outspread, what is to prevent her using the other hand and arm to draw a diamond point slowly and heavily along the glass, close to the metal?'

'By Jove! what indeed?'

'And why may not this act be repeated, three or four times, say, by the same woman, slightly changed as to dress, as she could have been? Lausch, you recall, accosted her.'

'Yes.'

When Dave grew laconic I knew him to be almost convinced.

'You will recall how each of the attendants remembered one or more instances of persons lingering long near the gems, or crowding so close as to attract the attention of some of them.'

'Umph!'

'And Lausch distinctly remembered how a good-natured guard came to his aid just as he was about to close his exhibits, and stood with his back to the case, and his arms carelessly outspread upon the edge chaffing with a group of late sight-seers, and keeping them from annoying him (Lausch) while he made things secure. Now I don't say that it was done, but I can see how that guard might have played into the hands of the gang, who might have been at hand three or four strong. Observe, the cases were high at the inner sides and shallow at the front, and while the top sheet of glass, for purposes of display, was a large one, those forming the outer side were small and set into stout bronzed squares not to exceed seven inches in depth and ten in length. Now, we will note that the back of the case, besides being higher than the front, is not of glass, but of wood, to admit of the use of a mirror for lining, and to double the show and glitter of the gems.'

'Upon—my—word!'

'Now let us suppose our guard as standing before the case and directly in front of the diamonds. He is facing outward, and before him, hovering close, are some others, two or three, or more. On the other sides of the octagonal pavilion the other assistants are busy "closing up." Lausch in person presides at the small safe in the centre of the place. Now, while he is busy, with his eyes averted for a moment, a hand thrust under the outstretched arm of the guard may gently press something adhesive against the already cut glass and pull it out, and soon, when Lausch bends down to open the safe, or to place some article therein, the hand draws out the little tray of gems; it was small, and could have been concealed under one of those wraps thrown conveniently across the arm. Now, a little ruse to substitute the false gems and replace the glass under the guard's concealing arm, and the thing is done. If it all happened at the closing hour, when the big building was shadowy and one could see clearly only a short distance, when every exhibitor was occupied with his own, and visitors, for the most part, were intent upon reaching the nearest exit—it was bound to succeed. Of course this is all theory, but——'

'It's the explanation of that theft, or I'm a sinner!' cried Dave, jumping up and beginning to pace the floor nervously. 'Carl, old man, I'll never chaff your "bump of imagination," after to-day. I'm ready to begin work on just that theory.'

'Steady, steady, Dave.'

'All right, sir; at least we can make a beginning—we can find that guard.'

'How?'

'Take his description from Lausch—find out who was detailed here——'

I put up my hand, and he stopped—staring.

'Dave, there is not a Columbian guard on the force who would, or could, have played that part—if it was played. It was simply one of the band wearing a guard's uniform.'

My friend sat down opposite me, and for some time not a word passed between us. Then he took up his notebook, and, drawing a small table toward us, said:

'Let's go over the ground slowly, and see if there is anything here to corroborate your theory, or to point to any other conclusion.'

And now I knew that Dave was fixed, so far as his opinions were concerned, and that while he might declare himself convinced by my wisdom, he had been all the time simply establishing his own convictions, and that he was now ready for earnest work.

It was some time before we came out from the superintendent's little inner sanctum, but we were now quite ready to begin our campaign; and when we were given carte blanche as to methods, and were promised as many men as we might need for the work, we could ask for nothing more, or better.

Our first demand was peremptory. There must be no publicity; no word of the robbery must reach the vigilant reporters who were everywhere in search of news.

Next, we caused an accurate description of Greenback Bob to be sent to all the gates and different districts, with orders for an instant report of the fact should he be seen, and that once seen he must be constantly shadowed.

Before we left the place we had arranged with Lausch to put a man of our own choosing into the pavilion, whose business it would be to keep constant watch over his people. For while he was ready to vouch for their honesty, we were not; rather, we were not willing to let any possibility of a clue escape us. A second man was placed where he could cultivate these people, and as much as possible outside of business hours. Not that we expected much from this, for we had seen no slightest sign of dishonesty among these people, who seemed to shun all society and to have no acquaintances outside their own pavilion.

After considering long, we decided not to bring the name of Delbras into the case, or to attempt to set any watch upon him in the regular way. To 'locate' Delbras should be our own especial work, and to freshen our memories we reviewed the information furnished our chief by the French commissaire.

So far as was known there was no picture of him extant, and the French report described him about as follows:

'Nationality, French; age, probably about thirty to thirty-three years; height, six feet, or nearly; weight, one hundred and seventy-five pounds, approximate; figure good; square shoulders, military air; features, regular; thin lipped; chin sharply pointed; wears at times heavy beard, at others moustache and goatee; eyes dark, called black; hair same, heavy, and sometimes worn quite long; hands well kept, with long slender fingers; speaks English perfectly, accomplished, etc.; a small triangular scar upon temple close to roots of hair. Known to have been in Paris and London in early winter, and to have crossed to New York about January 1st. Returned to Paris some time in March, and crossed last to New York in early May by steamer Normandie.'

'Well,' had been Dave's comment as we reperused this summary of M. Delbras, 'he may disguise himself in many ways, but he can't change his height very much, nor the colour of his eyes, nor his "regular features"'—Dave's features were not strictly regular, and it was a weakness of his always to resent this descriptive phrase—'nor his slim fingers, nor the scar on his temple close to the roots of the hair.'

We had spent a long morning in the rooms of the Secret Service Bureau, and as we were about to take leave, with but a step between us and the outer door, it was hastily opened and a guard entered, followed by two people whom I recognised as Farmer and Mrs. Camp. With a backward step and a quick glance at Dave, I turned and deliberately seated myself.

The only occupants of the outer office at the moment of their entry were the officer in command, who had just accompanied us from the inner office, and the subordinate who was in charge of this outer office, where complaints were received and first hearings granted.

I had drawn back quickly, but the eye of Mrs. Camp was still keen, though she looked a trifle subdued.

'The good land!' she ejaculated, catching at her husband's arm. 'Here's one of 'em now, Camp! They've caught him, anyhow!'

The words furnished Dave with a clue to the situation, and he dropped into a chair beside me, and, after one droll look in my direction, gave himself up to a fit of silent mirth.

Meantime the guard had advanced with dignity and announced to the officer at the desk:

'This man has a complaint to bring, sir.'

'Wait!' It was Mrs. Camp, standing determinedly near the door of entrance, who spoke. 'Afore you make a complaint, Adam Camp, about a raskil that ain't here, s'pose you jest make sure that this here one that is here in our midst don't git away.'