Mona felt very weary after the unusual excitement of the evening; her nerves were also considerably unstrung, and she resolved not to wait for Mrs. Montague’s return, but retire at once.

She arose and began to prepare for bed, but having sent some clothing away to be washed that morning, she found that her night-robe had gone with the other articles, and unlocking her trunk, she began to look for another.

“I thought I put an extra one in the tray,” she mused, as she searched for but failed to find it.

This obliged her to remove the tray and to unpack some of the contents beneath.

While thus employed she took out a box, and without thinking what it contained, carelessly set it across a corner of the trunk.

She finally found the garment she needed, and then began to replace the clothing which she had been obliged to remove during her search.

While thus engaged she turned suddenly to reach for something that had slipped from her grasp, and in the act she hit her elbow against the box setting on the corner of her trunk, and knocked it to the floor.

“Oh! my mirror!” she cried, in a voice of terror, and hastily gathering up the box, uncovered it to see if the precious relic had been injured.

To her great joy she found that it had not been broken by the fall; but as she lifted it from the box, to examine it still further, the bottom of the frame dropped out, and with it the things which Mr. Dinsmore had concealed within it.

“Mercy!” Mona excitedly exclaimed; “it looks like a little drawer, and here are some letters and a box which some one has hidden in it!  Can it be that these things once belonged to Marie Antoinette, and have been inclosed in this secret place all these long years?” she wonderingly questioned.

“No, surely not, for they would be yellow with age,” she continued, as she began to examine them.

“Ah!” with a start, and growing pale, “here is a letter addressed to me—­For Mona—­and in Uncle Walter’s handwriting!  He must have known about the secret of this mirror, and put these letters here with some special object in view.  What can it mean?”

She grew dizzy—­almost faint with the excitement of her discovery, and the things dropped from her nerveless fingers upon her lap.

“There is some secret here!” she whispered, as she gazed down at them, an expression of dread in her startled eyes.  “Perhaps it is the secret which I have so long wanted to know!  Can it be that the mystery of my mother’s sad fate is about to be solved—­that Uncle Walter had not the courage to tell me all, that never-to-be-forgotten morning, but wrote it out and hid it here for me to find later?  Ah!” and she lifted her head as if suddenly recalling something, “this was what he tried to make me understand the day he died!  He sent me for the mirror, not to remind me to keep it always, as I thought at the time, but to explain the secret of it, so that I could find what he had hidden here.  Oh, how he suffered because he could not show me!  Why could I not have understood?” and her tears fell thick and fast, as she thus lived over again that painful experience.