“I begin to have my suspicions,” said Frank sharply.
“If you wait a little longer, and go by there with your eyes shut, my lad, you will have something more than a suspicion.”
“Horrible!” said Frank shortly, as he once more raised his glass to his eyes. “You have given me the clue. I can make it out clearly now. Some poor camel that has strayed and lost its way, I suppose. Died from hunger and thirst.”
“More likely from old age or overwork,” replied the professor; “a milestone, only one of the many that mark the caravan tracks across the desert. Some one must have passed here within forty-eight hours.”
“How do you know?”
“By the appearance of that milestone. If we came by here to-morrow there would be nothing visible but some whitening bones. Look yonder without the glass. Look straight past the leading camel, low down at the horizon, and now raise your eyes. What can you see?”
“Glare,” said Frank.
“Try again.”
“Nothing but more glare, and the atmosphere quivering as it rises from the sand.”
“Try once more,” said the professor. “I can see one—two—three. Look higher.”