And then all at once Grannie stopped again, this time at the top of a high ridge. She shielded her eyes and stared off into the plain we had just crossed.
"Billy-boy," she said to me in a strange voice, "look down there and tell me what you see."
I followed the direction of her hand and a shock went through me from head to foot. Down there, slowly toiling across the sand, advanced a party of four persons. In the lead was a little old lady in a black dress. Behind her strode a grizzled Earth man in a flop-brimmed hat, another Earth man, and a Martian.
Detail for detail they were a duplicate of ourselves!
"A mirage!" said Ezra Karn.
But it wasn't a mirage. As the party came closer, we could see that their lips were moving, and their voices became audible. I listened in awe. The duplicate of myself was talking to the duplicate of Grannie Annie, and she was replying in the most natural way.
Steadily the four travelers approached. Then, when a dozen yards away, they suddenly faded like a negative exposed to light and disappeared.
"What do you make of it?" I said in a hushed voice.
Grannie shook her head. "Might be a form of mass hypnosis superinduced by some chemical radiations," she replied. "Whatever it is, we'd better watch our step. There's no telling what might lie ahead."
We walked after that with taut nerves and watchful eyes, but we saw no repetition of the "mirage." The wind continued to blow ceaselessly, and the sand seemed to grow more and more powdery.