Professor Duchard darted to the bench which lined one wall. Seized a strange-looking helmet which stood there. Rushed with it to Mark.
"The insulator-helmet!" he explained hastily, his blue eyes feverish with excitement. "Strap it on! Quickly!"
"Open up!" the alien voice roared again. "We want in!"
And then the angry accents of Adrian Vance:
"Break it down, officer! Don't let them get away!"
Mark hauled the frame on which the painting was stretched to a position in front of the mirror. Whirled back. Gripped his companion's hand.
"Will it work, professor? Will the mirror take me back through time?"
"That I cannot tell you, my boy. But it should. You know the formula I worked out. You understand the process by which it was constructed." A second's pause. "Actually, I believe it should work far better than the previous time mirror. The one Vance gave Elaine was very old, very crude. This one is the product of modern science, modern workmanship. It creates a tremendously larger rift in the space-time continuum—"
A shot rang out.
At the other end of the laboratory, the outside door burst open, lock shattered. Uniformed police rushed in, Adrian Vance at their head.