Suddenly, as they came to the edge of a dry river bed, Dr. Kirshner halted his camel and looked about on the ground. The others waited a moment to see what he had discovered.
“An ancient tool of flint,” he announced, commanding his camel to kneel.
The archæologist picked up the instrument and examined it carefully with the aid of a flashlight. It was about a foot long and shaped to resemble a crescent. The inner edge was as sharp as a razor.
“Doubtless some kind of a knife,” Dr. Kirshner said, as the others crowded around him. “Shaped out of flint by people of the Neolithic age. Perhaps it was used to harvest crops.”
“Crops? In the desert?” Bob was amazed.
The scholar nodded.
“It is firmly believed that primitive people lived in what is now the desert rather than along river valleys of more modern prominence. Of course the Sahara was at that time much less arid, or dry, than it is today.”
Dr. Kirshner searched about for other relics, but found none.
“It is strange how that tool got on the surface of the ground,” he remarked, as they turned the dromedaries ahead. “Other expeditions have penetrated into this region, and it is quite obvious that they would have found it had it been in sight.”
“Perhaps a rainstorm washed it out of the ground,” suggested Mr. Holton.