"Who goes where?" interrupted Emma.
"Please be quiet," rebuked Grace.
"I am coming to that," resumed the guide. "Two things I wish you to look for, alkali crusts that may cover a tank, and discolorations on the desert. That is, if you find a spot darker than the prevailing color of the ground, that discoloration may be the result of moisture. Do you get me?"
"Yes," answered the Overlanders in chorus.
"In the event of such a discovery, shout, or if I am too far away to hear your voice, fire one shot into the air. About the crusts that I spoke of, when you find one, hop off and break it in. You probably will not see water, even though it is there, but, after you have broken open the crust, thrust your head into the opening and sniff the air."
"What we need is a thirsty bird dog in this outfit," observed
Hippy, without the suggestion of a smile on his face.
Hi Lang permitted himself a brief silent laugh.
"What are we to sniff for?" questioned Emma in all seriousness.
"For a damp odor. The air under the crust, too, will be perhaps a degree cooler than the outer air. If it is a dry tank you will get a dry, earthy odor that you cannot mistake. The one who finds water will, as I have suggested, shout or shoot. The others will hold their positions until I have investigated.
"Another thing. Ponies familiar with desert conditions, as most of ours are, sometimes can smell water when they can't see it. If one of your animals suddenly bolts in a direction that you think he should not go, give him his head for a little way. He may lead you to water."