"Also, I could not have crashed far offshore. Do you know how rapidly the water deepens off the island?"

"Not in feet. I know it's steep, though; large ships can come quite close to the reef."

"That's what I thought; and I was in shallow water. We crashed, we will say, within a two-mile radius of this point." The Hunter momentarily shaded, on Bob's retina, a point a little way off the shore from the beach. "And much of that can be eliminated. He certainly did not crash on shore; my instruments showed him sinking after the initial check. I am equally sure he did not land in the lagoon, since you say it is very shallow, and he must have struck hard enough to reach its bottom instantly-at a guess, he must have had over fifty feet of water; I certainly did, though not much over, I should say.

"We can, then, act on the assumption that he landed in the two-mile semicircle to the west of the island, centered just off-shore from your beach. I admit that is not an absolute certainty, and it may be hard to prove, but it gives us something to start on. Have you any other ideas?"

"Just questions. How long would it have taken him to get ashore?"

"Your guess is as good as mine. If he had the luck I did, a few hours. If he was in very deep water, with even less oxygen than I, and a stronger sense of caution, he might have spent days or weeks crawling along the bottom to shore. I myself would never have attacked that shark, or ventured to swim out of touch with the bottom, unless I had been very sure I was near shore."

"How would he have known the right direction? Maybe he's still crawling around down there."

"Maybe. However, with the storm that night he could have determined the direction of the breakers as easily as I did; and if the bottom slopes as steeply as you think, it would have furnished another clue for him. I don't think that problem would have been serious. Of course he is known to be a coward; that may have kept him with the wreckage of his ship for quite a while."

"Then in order to go any farther we'll have to explore the reef for a mile or so each way from the beach, to see if he left any traces. Is that right? And if he has, what do you suppose he will have done after landing-same as you?" "Your first guess is right. As for the question, that depends. He would certainly want to find a host as soon as possible; but whether he simply waited for one where he landed, or went in search of something suitable, is hard to say. If he landed at a spot where any artificial structures are visible, he would probably have made his way to them, on the theory that intelligent beings were bound to come to them sooner or later. It's something that can't be predicted exactly, that's why I said I would have to know all the circumstances to guess his actions."

Bob nodded slowly, digesting this. Finally he asked, "What sort of traces are you likely to find at his place of landing? And if you don't find any, what will we do?"

"I don't know." There was no indication which question was being answered; and Bob finally grew tired of waiting for further explanation. It bothered him, for even he could see that the methods they had just outlined were not very promising. He thought intently for a time, half hoping his guest would come out with some supplementary technique from his own science. Suddenly an idea struck him.

"Hunter! I just thought of something! Remember the only time you could get to me, that day on the beach, was when I fell asleep?" The alien expressed assent. "Well, won't the same be true of this other fellow? He couldn't catch a person, or at least couldn't do it without being seen. You said yourself that it would take several minutes to get right inside; and even if this fellow doesn't care about the feelings or health of his host, he still wouldn't want to be seen. So it ought to narrow things down a bit if I found out who had been sleeping near the water in the last few months. There aren't any houses near the sea -Norm Hay's is the closest, and there shouldn't be too many people who made picnics the way we did that day. How about it?"

"You may have a point there. It is certainly worth trying; but remember, there is no part of the island that he could not reach given time enough, and everybody sleeps at some time or other-though he mightn't know that, come to think of it. Certainly anyone who has slept near the shore is, as you say, suspect"

A change in the rhythm of the engines interrupted the thoughtful silence that followed this remark, and Bob went back on deck, to find that the tanker had slowed and was turning to line up for the entrance to the western passage through the reef. A hasty trip along the catwalks took them to the bow, from which an unobstructed view could be had of the north reef and lagoon.

The reef, it seemed to the Hunter, was not too encouraging a field of search. Certainly no human being could have hidden there for long; and while his quarry could undoubtedly remain concealed, life in such a place would not be pleasant. Long sections of the barrier were barely visible above water, their position betrayed mostly by the breakers. Some portions were higher and had accumulated enough soil to support sparse vegetation-even coconut palms in one or two places. As the tanker nosed into the narrow passage, he realized that, in spite of this, searching the reef for clues might not be easy; it was never possible for a person to travel more than a few rods on foot, as he could see from the broken-up nature of the barrier; and on the outer side at least boating would be extremely dangerous-the endless breakers crashing through the openings in the coral created fierce and unpredictable currents and eddies almost certain to sweep any small craft against the rock-hard roughness of the reef. Even the tanker, big as she was and with plenty of steerage way, kept to the center of the marked channel while Bob and the Hunter watched the coral slip by on either side.

Even inside the lagoon they stayed carefully between the buoys, the Hunter noticed; and he recalled what Bob had said about the shallowness of the water here. On either side of them, scattered over the several square miles between reef and island proper, were angular concrete bulks that the Hunter assumed to be the culture tanks. These were from two to three hundred feet on a side, but their walls did not extend more than five or six feet above the water. The nearest was too far away for small details to be made out, but the Hunter was pretty sure it was covered by a roof consisting mostly of glass panes, while small square superstructures at various points were connected by catwalks to each other and to a diminutive landing stage on the side toward the channel.

Ahead of them was a larger structure, rather different in detail, and as they approached its purpose became evident Like the tanks, it was rectangular in shape, but it rose much higher out of the water-almost as high as the tanker's bridge for the central portions. The "deck" level was lower but still considerably above that of the culture tanks. This surface was covered with various structures, some obviously storage tanks and pumps, others more obscure in nature. On the side toward the approaching vessel were great mooring cables and even bigger hoses, with twenty or thirty men visible working around them. The structure obviously was the dock to which Bob had referred and which was used to store and transfer the fuel oils which were the chief product of the island.

Both watchers looked through Bob's eyes with interest as the tanker glided in to the dock and settled against the fenders. More lines snaked across and were pulled aboard, drawing the hoses after them; and in a remarkably short time the thudding of pumps showed that the last eight days' production was flowing into the tanker. It took a hail from the bridge to distract them from the process.