"No, I'm all right," answered Dick quietly, "but I'm wondering how I'm going to explain a mirage to these savages."
"A mirage!" exclaimed Dan with a catch in his voice. "So that's why we seemed to be getting farther away from that green spot all the time. But Dick, are you certain? I'd have sworn it was the real thing."
But even as they talked, Dan noticed the thinning haze ahead. It seemed to be rising and soon disappeared into the sky.
"Say, Dick, when did you catch on?" asked Dan.
"About five minutes ago. How am I going to explain it to them? They may never have seen one and may think that it is black magic. See, the caravan has vanished, too."
"Tell them it's Cimbula out there," said Dan with a laugh. "They'll believe that, all right."
While the boys were talking, the haze dissolved completely, leaving a far stretch of sandy waste.
"Ah-woe Tahara!" moaned Raal touching Dick's arm. "Look ahead. The spirit of evil has swallowed up the oasis. It is a warning, O Master. I have seen it many times before."
Dick gave a sigh of relief. At least the mirage was not unknown to the tribesmen.
"A warning, what do you mean, Raal?" asked Dick.
"Thus comes the oasis on the desert at times, leading men to destruction. Warriors depart to take possession of the new land and find themselves without food and drink. They ride around in circles in order to find the green oasis. Then at last the demons gobble them up. Did you not see the caravan disappear? It is a bad omen, so say my people."
Some of the tribesmen shielded their faces against the evil eye while others muttered anxiously. A few turned as if to flee back to their own land but at a sharp command from Dick they followed grumbling.
Dick halted his riders and they ate a hasty lunch while shielding themselves in the shadow of their horses.
Late that afternoon they came to the oasis in the desert. The men threw themselves flat on their stomachs by the spring, dipping up the water in their hands and drinking with loud sucking noises. It was hard for both man and beast to restrain the desire to overdo, for their parched throats seemed never to get enough.
As soon as the quickly prepared meal was over, the men stretched out on the green grass beneath the palms and slept.