'I confess,' he said, 'that I cannot understand why those people should be a hindrance; nevertheless, I am ready to believe that your reason is good and sufficient.'

'Thank you.'

'I trust,' he hastened to add, 'that you will judge me as generously when I say that I cannot oblige you. I know the name of the lady, it is true; but, much as I may desire to serve you, I cannot do so. My desire to avoid the lady, to remain unrecognised by her, is as strong as is yours to hold aloof from her escort. It's an odd position,' he added, with a slow half-smile. 'I trust the contents of Miss--of the bag were not of too great value--not indispensable to her?'

'By no means--quite the contrary; and this being the case, we will trouble ourselves no more about it. Of course I can't urge my request under the circ.u.mstances.' I could not repress a smile at the absurdity of the situation. 'And to say that I don't bear malice, as they say in making up a quarrel, let us exchange cards.' I produced my card, a simple pasteboard of the size known as the visiting-card, and with only my name engraved across it.

The guard drew back a step, and again that ready flush dyed his face.

'Pardon me. You are addressing me as one gentleman to another, and if I were to give you the name by which I am known here it would not be my true one. I will not give you a fict.i.tious name, and--I can give no other.'

I was silent a moment, then--'I will not urge you,' I said; 'but at least, as man and man, equals, we can shake bands.' And I held out my own.

His face cleared instantly, and he promptly placed his palm upon mine.

'I can do that,' he said, 'as man to man, as an equal, and'--he threw back his handsome head--'I shall never, I trust, have reason to hesitate before giving my hand as an honest man to an honest man; and now----' He paused, and I with him.

'And now,' I supplemented, 'we are neither of us idlers. This is your beat?'

'For the present.'

'Then--I hope we shall meet again. Success to you.'

'And to you.' He lifted his hat as I turned away, and looking back a moment after, I saw him once more a Columbian Guard on duty, piloting an old woman across the street and away from a sprinkling-cart.

'Handsome enough to be a prince,' I thought. 'An American prince, and poor, doubtless. Honest, I'll wager; and with a mystery. I wonder if the world is pouring all its mysteries into this White City of the world.'

CHAPTER IX.

IN DISGUISE.

Two days had pa.s.sed since my talk with my friend the guard, and although Brainerd, myself, and others had thoroughly searched Midway Plaisance, hoping to obtain a glimpse of our quarry or a hint of their presence, we had been unsuccessful. We found many things in Midway, but neither Greenback Bob nor his friend Delbras.

'I tell you,' Dave had said on the previous night, when we were discussing our failure and its probable reasons--'I tell you, Carl, these men began their business in Midway--I'm sure of it; and I solemnly believe that you're the fellow that scared them away.'

'I, indeed--how?'

'Simply by springing upon them in that Camp affair. I believe they spotted you.'

I felt chapfallen, for I was more than half inclined to believe that Dave's notion was the correct one, and I wondered that I had not thought of this myself.

'And if they did,' went on Dave, 'it would be the most natural thing in the world for them to "fold up their tents like the Arabs," etc.

Don't you think so?'

'Granting your first premises,' I conceded grudgingly, 'your second, of course, are tenable. Perhaps you have an idea where their "tents"

are now spread?'

'Oh, you always try the sarcastic dodge when you are beaten a bit,'

grinned Dave good-humouredly; 'but that's all right. I think we may as well give the Midway a rest, at any rate.'

'I suppose you have noted that the Woman's Building has had more than its share of stealing of late?' said I.

''M--no.'

'Well, you should read the papers, and look in at the bureau, once a day at least. They've had an attack upon the exhibits--failed, I believe--and a number of pockets picked.'

'Do you suggest the Woman's Building?'

'To-morrow I suggest the vicinity of the Court of Honour and the Administration Building. It's the Princess Eulalia's day, you remember; or had you failed to note that?'

'Go on, boy; wound me where I'm weakest,' scoffed Dave.

But I chose to ignore Dave's chaff.

'I suggest that we join the crowd early, and stay with it late.'

'Done!' cried he.

'It's hard to tell where they will elect to work. There will be a thinning out inside the buildings, but a crowd outside, and such a crowd as this will be--all with necks craned and attention fixed; ladies in gay attire, the cream of the city's visitors as well as the other side; and there will be at least half a dozen false cries of "There she comes!" and somebody's pocket will suffer at each cry.'

'Right you are!' agreed Dave. 'It'll be a swell crowd, and it's my opinion that our men will be in the thick of it.'

Early the next morning I went to see if anything had been reported concerning the diamond robbery, for as yet little had been accomplished. There was one of the attendants, a young woman, whom I had felt uncertain about. She was pretty, and I thought artful and vain; and I had learned from another employe of the Lausch Pavilion that she had formed the acquaintance of a rather flashily dressed person wearing much jewellery, and that just before the robbery she had been seen to receive two or three slyly-delivered _billets-doux_.

The girl was being closely watched, and one of the guards, who was stationed near, and who was said to have been seen loitering near the pavilion oftener and longer than was needful, was likewise under close surveillance.

But this morning there was something to report. It did not come through any of the men at work upon the case, nor was it in the nature of a discovery. It was an anonymous letter, and it came through the United States mail, having been posted in Chicago, at the up-town post-office.

It was addressed 'To whom it may concern,' at the bureau, and was brief and to the point.

'If you do not want to waste time,' the letter began, 'turn your attention to the men in charge of the robbed jewellery exhibit; and if you also keep an eye upon a certain up-town man who keeps a place advertised as a "jewellery-store," and with rather a shady reputation--a man not above doing a little business in uncut gems, say, in a very quiet way--you may find some of the lost gems between the two.'

There was no signature, and I saw at a glance that the writing was carefully disguised.

I was not inclined to treat this doc.u.ment seriously, though I could see that it had created quite a sensation at the office, and when asked my opinion concerning it I said:

'If this letter means anything but to mislead, it can mean but one of two things; either it is written by one of the thieves to draw us away from the right track, or it is written by someone who belongs to a gang, and who means, if possible and safe, to sell out his comrades for all he can get and a promise of safety. I've seen this done.'

'And what is your opinion?'

'I'm more than half inclined to think it is a hoax.'

'As how?'