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.'
Davenport rose triumphantly to his feet. 'Let me have your opinion in writing,' he said, hand on blaster, 'and that will be good enough to get me permission to use a psycho-probe.'
Louis Peyton, dazed and unresisting, had only the numb realization that any testament he could now leave would have to include the fact of ultimate failure.
***
My stories generally bring me mail from my readers- usually very pleasant mail, even when some embarrassing point must be brought up. Alter this story was published, lor instance, I received a letter from a young man who said he was inspired by Dr. Urth's reasoning to check on the problem of whether differences in weight would really affect the manner in which an object was