All along the line the girls were trying to make merry, trying to forget the terrible heat, a deadly burning heat, but their efforts in this direction were not very successful.
Heat waves shimmered over the white sands of the desert with not a breath of air stirring to relieve the deadly monotony. It did not seem possible to Elfreda Briggs that human beings long could endure such heat, and she wondered at the cheerfulness of her companions.
Hi Lang rode around behind the line of riders to see what it was that Emma Dean had discovered, but he paused at the dry water hole for but a moment, then hurried back to his position. Now and then one of the riders would dismount and examine a patch of ground, only to meet with disappointment.
They had come up to a vast cup-like depression in the desert, white with the alkali crust that covered its bottom, when Hi fired a signal shot to indicate that they were to halt for a rest.
"What is that big hole?" called Lieutenant Wingate.
"A prehistoric lake, in whose alkaline dust no plant, not even sage-brush, can grow, and upon which a puddle of rainwater becomes an almost deadly poison. This is one of the most thoroughly hated spots on the desert, hated and shunned by most of those who travel this way."
"Is there not water under the crust at the bottom?" asked Miss
Dean.
"Not a drop. There probably has not been in centuries. No water is known to have been found within a few miles of this spot either, but, as I have said, one never knows, and the traveler must take nothing for granted."
"Fine place for a summer outing," observed Hippy.
"Probably there is on all the globe no other spot more forbidding, more desolate, more deadly," added the guide. "We must be going. Move on!"