ep in his eyes.

"Is it--"

Professor Duchard nodded.

"It is. That was the secret, my boy. The secret we sought but could not
find. The time mirror is merely a special glass which has been subjected
to a terrific electrical discharge, then silvered. That piece on the
floor is worthless, of course; too many elements were uncontrolled.

"But knowing the formula as we do; knowing exactly what we are searching
for and how to prepare it, I would stake my reputation that we can
duplicate the mirror Adrian Vance sent to Elaine."

Mark's eyes were gleaming. His jaw hard.

"Then do it!" he commanded.

"But what good would it do? We cannot bring Elaine back--"

"Maybe not." The other's tanned face was grim. "But we can send me back
to where she is."

"Send you back!"

"Yes." A pause. "You see, I've been thinking about the things you've
told me, Professor Duchard. About time travel, and how it works.

"You say we can't save Elaine. Well, that's probably true. Maybe she's
got to die in France, back in the days before the revolution."

A tremor of emotion passed over him as he said it. He swallowed hard.
Then:

"But if she must die, she can at least die easily. Cleanly. Quickly,
with a knife through her heart. She doesn't have to go the way Adrian
Vance wants her to--tortured by a bunch of drunken scum, then cut to
pieces without a chance to fight back."

* * * * *

There was pain in the professor's face, too, when he answered.

"I wish it were as easy as that, Mark."

Mark's voice was fierce.

"What's wrong with it? What's to stop me?"

The other sighed. Brushed back white hair with a sweep of one frail
hand.

"You cannot change history, my boy," he said sadly. "A study of
cosmology would show you that such things are immutable. You can go
backward or forward through time and participate in them, but you cannot
change them."

"How do you know? Who's traveled through time and then come back to say
we can't change events?"

"You do not understand--"

"And I don't care!" the younger man flared. "I may fail--but I'm going
to try! I'm not going to sit here, waiting for Elaine to die--"

"But you would have no memory of your life in this century! Remember
what Vance said--"

"Right. That's the one thing that might stop me. I'm counting on you to
take care of it, though. Is there anything you can do?"

There was a long moment of tension-studded silence. Then:

"Perhaps th