Frank knew the country so well that he had no difficulty in guiding them to the spot where he and Mark had separated.  From here they followed the star that Frank had pointed out to Mark, and riding abreast, but about a hundred feet apart, they kept up a continual shouting, and occasionally fired a gun, but got no answer.

At length Mr. March detected a glimmer of light on the ground, and dismounting, found a few charred sticks, one of which still glowed with a coal of fire.

“Halloo!” he shouted; “here’s where Mark emptied his fire-pan.”

They all gathered around, and having brought a supply of light-wood splinters with which to make torches, they each lighted one of these, and began a careful search for further evidences of the missing boy.

A shout from Jan brought them to him, and he showed the broken fire-pan which he had just picked up.

A little farther search revealed the deep imprints of the horse’s hoofs when he had plunged and reared as the burning brands fell on his back; and then, step by step, often losing it, but recovering it again, they followed the trail until they came upon the rifle lying on the ground, cold and wet with the night dew.

Mr. March, holding his torch high above his head, took a step in advance of the others as they were examining the rifle, and uttered a cry of horror.

“A sink-hole!  Good heavens! the boy is down there!”

A cold chill went through his hearers at these words, and they gathered close to the edge of the opening and peered into its black depths.

“We must know beyond a doubt whether or not he is down there before we leave this place,” said Mr. Elmer, with forced composure, “and we must have a rope.  Frank, you know the way better than any of us, and can go quickest.  Ride for your life back to the house, and bring that Manila line you used to catch the alligator with.  Don’t let his mother hear you—­a greater suspense would kill her.”

While Frank was gone the others carefully examined the “sink hole,” and cut away the bushes and vines from around its edges.  It was an irregular opening, about twenty feet across, and a short distance below the surface had limestone sides.

Begging the others to be perfectly quiet, Mr. Elmer lay down on the ground, and reaching as far over the edge as he dared, called,

“Mark! my boy!  Mark!” but there was no answer.  Still Mr. Elmer listened, and when he rose to his feet he said,

“March, it seems as though I heard the sound of running water down there.  Listen, and tell me if you hear it.  If it is so, my boy is dead!”

Mr. March lay down and listened, and the others held their breath.  “Yes,” he said, “I hear it.  Oh, my poor friend, I fear there is no hope.”

The first faint streaks of day were showing in the east when Frank returned with the rope and an additional supply of torches.

“Now let me down there,” said Mr. Elmer, preparing to fasten the rope around him, “and God help me if I find the dead body of my boy.”