More, he sensed at once that this drum was sending some message. There was a rapidity about the strokes, a variation in the periods of pulsation, which was at once apparent.
He tried to line up the sound accurately, and fancied that he had it pretty well located, when it ceased abruptly. There was none of the gradual tapering off into silence which had characterized the other sounds from the big drum. It was simply that the drum was beating with steady resonant volume at one moment, and at the next it had ceased.
Phil listened.
The silence of the tropical jungle hemmed him in.
Then he heard something else, a rapid pound, pound, pound, that seemed to jar the earth. He crouched down in the shadows, and waited. The pounding grew louder, kept the same rhythm. A dark shape, moving through the trees, became visible.
Phil saw it was a savage, naked except for the loin cloth, and that the man was running down some established trail. The sound of his bare feet thudding on the ground was the noise that Phil had heard, some little time before he glimpsed the runner, and that thudding of the feet continued some little time after the naked savage had vanished in the jungle growth.
Phil waited, aware now that he must move with caution. He was on an island that was peopled with a savage and warlike tribe. He had no weapons worthy of the name, no means of escape. And he had the responsibility of caring for two people, both of whom were utterly helpless as far as any actual ability to care for themselves against any such obstacles.
Phil decided that he would work his way back to the camp, taking care not to leave a trail that could be followed, warning the two that they must take no chances of showing themselves, getting them, perhaps, in a better place of concealment.
He started through the brush, realizing that the trail which the native had followed was but a short distance below him. Evidently that trail had crossed downstream, then zigzagged up on the side of the stream he had crossed.
He had not taken more than a single step when he heard the smaller drum again, volleying forth a message, and almost at once the big master drum started its deep-throated booming.
Phil, standing there, perspiring, alarmed, every sense alert, could not be certain, but he felt that the big drum was relaying the same message that had been received by the smaller drum, sending it booming forth to every part of the island.
For there could be no question now but what the big drum was conveying a message. The change in tempo of the throbbing sounds could be readily perceived.
Suddenly the noise of a rifle shot cracked out, and it was followed almost at once by two more shots.
The noise of the reports drowned, out the sound of the drums as they echoed from crag to crag.
Then, after the noise of the shots had died away, there sounded the noise of the big drum again, booming forth a series of repeated signals. There were three rapid beats, a delayed moment, then two slow beats, a pause, and then one single booming beat of noise. Following that was silence, a silence which lasted for several seconds. Then the big drum repeated the signal.
Phil listened to the repetition of that signal for several minutes, and came to the conclusion, without having any evidence to base it on, other than the fact that the smaller drum was silenced, that the big drum was booming forth something in the nature of a call signal, waiting for a reply from the smaller drum.
Phil decided that the girl and Professor Parker could hear the signal of the master drum, which was booming in increased volume with every repetition. Indeed, it seemed that the signal must carry to every part of the island.
And Phil felt certain that the warning conveyed by that drummed signal would be sufficient to apprise the girl of the presence of hostile savages, and that she would use every precaution to insure against discovery.
The savage he had found had been armed only with bow and arrow. The sound of the rifle shot indicated the presence of a more civilized man, and it was very possible that some other white man, better armed, had been caught by the same tidal currents which followed the shifting of the poles of the earth, and that those currents had deposited him upon the same island.
Phil changed his plans, determined to make his way toward the place from which he had heard those rifle shots, particularly as they had seemed to be almost in the same locality as the source of the drum beats from the smaller drum.
Phil had an idea speed meant everything. He cast caution to the winds, broke from his concealment, found the trail the running savage had been following, and set out along it with swinging strides that devoured distance.
But Phil was taking care lest he should run into an ambush, and his trail-wise eyes took in every detail of his surroundings.
The trail was beaten hard by naked feet. It wound like a black ribbon through the dense growth of tree and shrub, vine and creeper, following the contours of the upper levels with a slope that showed some considerable engineering efficiency in its construction, an efficiency which is the result of laborious study in civilized schools, yet which comes instinctively to game animals and savages.
Phil dropped down a gully, following the trail, saw where a branch trail turned into the shrub on a shoulder of the next ridge, and decided to follow that branch trail. He was, he realized, getting close to the place from which that shot had sounded. Had he been trailing a deer hunter, he would have started to look for a dead deer along in here.
He slowed his pace, moved with every sense alert, his eyes taking in every bit of the slope, penetrating the shadows of the jungle.
It was the sight of a brown foot protruding into a patch of sunlight which sent him jumping into the shrubbery beside the trail, the bow raised, arrow on the string.
But the foot remained motionless, the toes pointing upward.
Phil stepped forward, silently, cautiously.
The foot was motionless. As he walked, a leg came into view above the foot, then another foot and leg, the latter twisted into a grotesque position.
Then, rounding a tree trunk, he saw the man.
Chapter 7
The Murderer
He knew, then, the target that had received those rifle bullets. The man had been struck in the back, a little to one side of the right shoulder blade. The bullet had ranged through the chest, emerging from the left side. Death had been instantaneous, and the heavy drum stick, padded with a ball of animal hide which the fingers of the right hand still held, told the story.
There was a huge drum suspended from the branches of the tree by a twisted grass rope. The drum was made from a section of a hollowed tree trunk, and the hide which stretched across it was apparently exceedingly heavy. Phil found himself wondering if it could be a strip of elephant hide.
The drummer was dressed as the others had been dressed, simply in a loin cloth. But there was no ivory ornament thrust through his nose, although the skin of the chest showed a species of tattooing.
Phil stepped around the body, mindful of the presence of the man with the rifle, mindful, also, of the fact that the savage had been shot down without warning, and in the back.
The possibility that the man who had fired that rifle shot would be a friend and ally became more remote as Phil reconstructed the scene of the shooting.
The drummer had been standing before the drum, in the very act of beating the resonant hide. Then had come the shot, and the force of the bullet had hurled him to one side, sprawled him in the position in which he now lay.
But how about the other shots?
Obviously this man had been taken completely by surprise. That meant that he had not received any warning of the presence of his slayer until the bullet had crashed him down into death.