'Now what do you want of me?'

'Proof that he was on the Moon sometime in August. It's got to be done quickly. I can't hold him on suspicion much longer. And if news of the murder gets out, the world press will blow up like an asteroid striking Jupiter's atmosphere. A glamorous crime, you know-first murder on the Moon.'

'Exactly when was the murder committed?' asked Urth, in a sudden transition to brisk cross-examination.

'August twenty-seventh.'

'And the arrest was made when?'

'Yesterday, August thirtieth.'

'Then if Peyton were the murderer, he would have had time to return to Earth.'

'Barely. Just barely.' Davenport's lips thinned. 'If I had been a day sooner-If I had found his place empty-'

'And how long do you suppose the two, the murdered man and the murderer, were on the Moon altogether?' • 'Judging by the ground covered by the footprints, a number of days. A week, at the minimum.'

'Has the ship they used been located?'

'No, and it probably never will. About ten hours ago, the University of Denver reported a rise in background radioactivity beginning day before yesterday at 6 p.m. and persisting for a number of hours.

It's an easy thing. Dr. Urth, to set a ship's controls so as to allow it to blast off without crew and blow up, fifty miles high, in a micropile short.'

'If I had been Peyton,' said Dr. Urth thoughtfully, 'I would have killed the man on board ship and blown up corpse and ship together.'

'You don't know Peyton,' said Davenport grimly. 'He enjoys his victories over the law. He values them. Leaving the corpse on the Moon is his challenge to us.'

'I see.' Dr. Urth patted his stomach with a rotary motion and said, 'Well, there is a chance.' That you'll be able to prove he was on the Moon?'

That I'll be able to give you my opinion.'

'Now?'

The sooner the better. If, of course, I get a chance to interview Mr. Peyton.'

That can be arranged. I have a non-grav jet waiting. We can be in Washington in twenty minutes.'

But a look of the deepest alarm passed over the plump extraterrologist's face. He rose to his feet and pattered away from the T.B.I, agent toward the duskiest corner of the cluttered room.

'No!'

'What's wrong, Dr. Urth?'

'I won't use a non-grav jet. I don't believe in them.' 

Davenport stared confusedly at Dr. Urth. He stammered, 'Would you prefer a monorail?'

Dr. Urth snapped, 'I mistrust all forms of transportation. I don't believe in them. Except walking. I don't mind walking.' He was suddenly eager. 'Couldn't you bring Mr. Peyton to this city, somewhere within walking distance? To City Hall, perhaps? I've often walked to City Hall.'

Davenport looked helplessly about the room. He looked at the myriad volumes of lore about the light-years. He could see through the open door into the room beyond, with its tokens of the worlds beyond the sky. And he looked at Dr. Urth, pale at the thought of non-grav jet, and shrugged his shoulders.

'I'll bring Peyton here. Right to this room. Will that satisfy you?' Dr. Urth puffed out his breath in a deep sigh. 'Quite.'

'I hope you can deliver, Dr. Urth.'

'I will do my best, Mr. Davenport.'

Louis Peyton stared with distaste at his surroundings and with contempt at the fat man who bobbed his head in greeting. He glanced at the seat offered him and brushed it with his hand before sitting down. Davenport took a seat next to him, with his blaster holster in clear view.

The fat man was smiling as he sat down and patted his round abdomen as though he had just finished a good meal and were intent on letting the world know about it.

He said, 'Good evening, Mr. Peyton. I am Dr. Wendell Urth, extraterrologist.' Peyton looked at him again, 'And what do you want with me?'

'I want to know if you were on the Moon at any time in the month of August.'

'I was not.'

'Yet no man saw you on Earth between the days of August first and August thirtieth.'

'I lived my normal life in August. I am never seen during that month. Let him tell you.' And he jerked his head in the direction of Davenport.

Dr. Urth chuckled. 'How nice if we could test this matter. If there were only some physical manner in which we could differentiate Moon from Earth. If, for instance, we could analyze the dust in your hair and say, "Aha, Moon rock." Unfortunately we can't. Moon rock is much the same as Earth rock. Even if it weren't, there wouldn't be any in your hair unless you stepped onto the lunar surface without a spacesuit, which is unlikely.'

Peyton remained impassive.

Dr. Urth went on, smiling benevolently, and lifting a hand to steady the glasses perched precariously on the bulb of his nose. 'A man traveling in space or on the Moon breathes Earth air, eats Earth food. He carries Earth environment next to his skin whether he's in his ship or in his spacesuit. We are looking for a man who spent two days in space going to the Moon, at least a week on the Moon, and two days coming back from the Moon. In all that time he carried Earth next to his skin, which makes it difficult.'

'I'd suggest,' said Peyton, 'that you can make it less difficult by releasing me and looking for the real murderer.' 

'It may come to that,' said Dr. Urth. 'Have you ever seen anything like this?' His hand pushed its pudgy way to the ground beside his chair and came up with a gray sphere that sent back subdued highlights.

Peyton smiled. 'It looks like a Singing Bell to me.'

'It is a Singing Bell. The murder was committed for the sake of Singing Bells. What do you think of this one?'

'I think it is badly flawed.'

'Ah, but inspect it,' said Dr. Urth, and with a quick motion of his hand, he tossed it through six feet of air to Peyton.

Davenport cried out and half-rose from his chair. Peyton brought up his arms with an effort, but so quickly that he managed to catch the Bell.

Peyton said, 'You damned fool. Don't throw it around that way.'

'You respect Singing Bells, do you?'

'Too much to break one. That's no crime, at least.' Peyton stroked the Bell gently, then lifted it to his ear and shook it slowly, listening to the soft clicks of the Lunoliths, those small pumice particles, as they rattled in vacuum.

Then, holding the Bell up by the length of steel wire still attached to it, he ran a thumbnail over its surface with an expert, curving motion. It twanged! The note was very mellow, very flutelike, holding with a slight vibrato that faded lingeringly and conjured up pictures of a summer twilight. For a short moment, all three men were lost in the sound.

And then Dr. Urth said. Throw it back, Mr. Peyton. Toss it here!' and held out his hand in peremptory gesture.

Automatically Louis Peyton tossed the Bell. It traveled its short arc one-third of the way to Dr. Urth's waiting hand, curved downward and shattered with a heartbroken, sighing discord on the floor.

Davenport and Peyton stared at the grey slivers with equal wordlessness and Dr. Urth's calm voice went almost unheard as he said, 'When the criminal's cache of crude Bells is located, I'll ask that a flawless one, properly polished, be given to me, as replacement and fee.'

'A fee? For what?' demanded Davenport irritably.

'Surely the matter is now obvious. Despite my little speech of a moment ago, there is one piece of Earth's environment that no space traveler carries with him and that is Earth's surface gravity. The fact that Mr. Peyton could so egregiously misjudge the toss of an object he obviously valued so highly could mean only that his muscles are not yet readjusted to the pull of Earthly gravity. It is my professional opinion, Mr. Davenport, that your prisoner has, in the last few days, been away from Earth. He had either been in space or on some planetary object considerably smaller in size than the Earth-as, for example, the Moon.'