He sprang to catch it, but it avoided his fingers and fluttered out of the window.

Thrusting his head forth, he saw it sail away and settle slowly at the foot of one of the great trees amid which the academy buildings stood.
Out of the room darted Bart, and down the stairs he bounded.

He was soon outside, and, recovering the paper, which he readily found, he hastened back.
"Great Scott!" he muttered.

"I left that ring under the microscope!" The thought that he had allowed the ring to escape his sight for a moment filled him with anxiety.
What if he should not find it where he had left it a few moments before?
A cold sweat started out on his face, and he literally tore up the stairs and rushed headlong into the experimenting room, the door of which he had left open.
And then, when he looked for the mysterious ring, he found it had vanished!.