"May I interrupt, sir?" said Henry.

"Huh? Oh-no, I don't want any more coffee, waiter," said Peterborough, absently.

"No, sir. I mean, concerning the eclipse."

Trumbull said, "Henry's a member of the club, Martin. He broke the tie on the matter of the discussion. Remember?''

Peterborough put a hand to his forehead. "Oh, sure. Ask away-uh-Henry.''

"Actually, sir, would the photographs be that much better in a vacuum than in the thin air of the stratosphere? Would the difference in quality be enough to result in murder, unless Murderer was a close approach to a homicidal maniac?"

"That's the thing," said Peterborough, nodding. "That's what bothers me. That's why I keep saying I need a motive. These differences in quality of photos aren't big enough."

"Let us consider, then," said Henry, "Mr. Rubin's dictum that in telling a story one should look backward."

"I know the ending," said Peterborough. "I have the backward look."

"I mean it in another sense-that of deliberately looking in the other direction, the unaccustomed direction. In an eclipse, we always look at the Moon-just the Moon in a Lunar eclipse, and the Moon covering the Sun in a Solar eclipse-and that's what we take photographs of. What if we take a backward look at the Earth?"

"What's to see on Earth, Henry?" asked Gonzalo.

"When the Moon moves into the Earth's shadow, it is always in the full phase and it is usually completely darkened. What happens to the Earth when it moves into the Moon's shadow? It certainly doesn't darken completely."

"No," said Peterborough emphatically. "The Moon's shadow is thinner and shorter than the Earth's, and the Earth itself is larger than the Moon. Even when Earth passes as deeply as it can into the Moon's shadow, only a tiny bit of the Earth is darkened, a little dot of darkness that makes up, at most, about 1/600 of the Earth's circle of light."

' 'Could you see it from the Moon?'' asked Henry.

"If you knew where to look and especially if you had a good pair of binoculars. You would see it start small, move west to east across the face of the Earth, getting bigger, then smaller, and then vanish. Interesting, but certainly not spectacular."

"Not from the Moon, sir," said Henry. "Now suppose we reverse the positions of the characters. It is Victim who has the airplane and who can get a photograph from the stratosphere. It is Murderer who intends to trump his opponent's ace by taking a better photograph from space-a marginally better photograph. Suppose, though, that Victim, against all expectations, from his airplane over-trumps Murderer in his spaceship."

Avalon said, "How can he do that, Henry?"

"Victim, in his plane, suddenly realizes he needn't look at the Moon. He looks backward at the ground and sees the Moon's shadow, racing toward him. The Moon's shadow is just a dark dot when seen from the Moon; it's just the coming of temporary night as seen from the Earth's surface-but from a plane in the stratosphere, it is a racing circle of darkness moving at 1440 miles an hour, swallowing up the land and sea-and clouds, for that matter-as it goes. The plane can move ahead of it, and it is no longer necessary to take single snapshots. A movie camera can produce the most dramatic film. In this way, Murderer, having fully expected to outdo Victim, finds that Victim has captured world attention even though he had only an airplane to Murderer's spaceship."

Gonzalo broke into loud applause, and Trumbull said, "Right on!" Even Rubin smiled and nodded.

As for Peterborough, he fired up at once saying, "Sure! And the approaching shadow would have a thin red rim, for at the moment the shadow overtakes you, the red prominences cast their light unmasked by the Sun's white light. That's it, Henry! The backward look does it!-If I write this one properly, I don't care even if it doesn't sell.-I won't care even" (his voice shook) "if-uh-she doesn't like it and doesn't go out with me. The story is more important!"

Henry smiled gently and said, "I'm glad to hear that, sir. A writer should always have a proper sense of priorities."