They were off soon after that, but the mules had never seemed to move as slowly as they did that morning. Instead of an hour, more than two hours had passed before they finally came within hailing distance of the camp-fire. For some time, they had been finding difficulty in keeping it in sight, as the fire appeared to be dying down.
Tad shouted to attract the attention of the campers or the Professor to let them know the Pony Riders were coming. There was no reply, which caused the lads to wonder.
So they pushed the mules all they could, a vague apprehension that all was not as it should be, growing in their minds. They soon came upon the object of their search. What they found was a smouldering camp-fire.
"The camp is deserted," groaned Tad.
Not a person save themselves was within sight or sound. Professor
Zepplin, too, had disappeared.
CHAPTER XI
CHUNKY OBJECTS TO EGG WATER
"Well, doesn't that beat all!" marveled Tad.
"Certainly does," agreed Ned.
"Yes, but I don't understand—what does this mean?" exclaimed Walter.