“Had they baggage with them?” Mr. Rider questioned.

“Yes, a trunk and a good-sized grip,” said the man.

The detective thought a moment.

Then he called for writing materials, hastily wrote a few lines, which he sealed, and directed to “Miss Richards.”

“There is a young lady by that name stopping here, I believe,” he remarked, as he laid the envelope before the clerk.

“Yes; she is with a Mrs. Montague.”

“That is the lady,” said the detective.  “Will you see that this letter is given into her own hands, and privately?  It is a matter of importance.”

“Yes, sir, I will myself attend to the matter,” responded the obliging clerk.

Mr. Rider deposited a piece of silver upon the envelope, touched his hat, and walked briskly from the hotel.

He jumped into a carriage that was waiting before the door.

“To the Grand Union Station,” he ordered.  “Be quick about it, and you shall have double fare.”

The man was quick about it, but the train for Chicago had been gone some time.

Mr. Rider had of course expected this, but he at once sought an interview with the ticket agent, and made earnest inquiries regarding those who had purchased tickets for Chicago that morning; but he could learn of no persons answering to the description of the miner and his supposed mother.

If he could have obtained any intelligence regarding them, he had intended to telegraph ahead, and order their arrest when they should arrive at the end of their journey.  But of course it would be of no use to put this plan into execution now, as he doubted very much their having gone to Chicago at all.

He was very much disheartened, and retraced his steps to his hotel, with a sickening sense of total defeat.

“Tom Rider,” he muttered, fiercely, as he packed his own grip to take the first train back to New York, “you might as well give up the business and take up some trade; you’ve been hoodwinked by these clever thieves often enough.”

But there was a very dogged, resolute expression on his plain face, nevertheless, as he turned it northward, which betrayed that he did not mean to give up his search quite yet.

That afternoon when Mona went down to dinner, the clerk of the hotel waylaid her and quietly slipped an envelope into her hand.

“Thank you,” she said, in a low tone, and hastily concealed it in her pocket.

When she was alone again she broke it open and read, with almost as much disappointment as the detective himself had experienced, when he found that his birds had flown, these words: 

“Gone!  They gave us the slip about eleven o’clock.  Save the scrap of cloth—­it may be needed later.  R.”

“Oh, dear!” sighed Mona, regretfully; “and the Palmer robbery is still as much of a mystery as ever.”

CHAPTER X.