"Nothing remained but to search for his body. I was sure they had killed him and taken the chest. I had little expectation of finding him, dead or alive. None after I saw the stream of lava pouring into the sea. One saves his own life by instinct, I suppose. There I was. I had to live. It did not matter much, but I continued to do it by various shifts. That last day on the headland the fumes nearly got me. You may have noted the rather excited scrawl in the back of the ledger? Yes, I thought I was gone that time. But I got to the cave. It was low tide. Then the earthquake, and I was walled in.... Mr. Barnett's very accurate explosives--Slade's insistence--your risking your lives as you did, mites on the crust of a red-hot cheese--I hope you know how I feel about it all. One can't thank a man properly for the life....

"Oh, the pirates. Necessarily it must be a matter of theory, but I think we have it right. Slade and I built it up. For what it's worth, here it is. Let me see: you sighted the glow on the night of the 2d. Next day came the deserted ship. It must have puzzled you outrageously."

"It did," said Captain Parkinson, drily.

"Not an easy problem, even with all the data at hand. You, of course, had none. On Slade's showing, Handy Solomon and his worthy associates thought they had a chest full of riches when they got the doctor's treasure; believed they owned the machinery for making diamonds or gold or what-not of ready-to-hand wealth. It's fair to assume a certain eagerness on their part. Disturbed weather keeps them busy until they're well out from the island. Then to the chest. Opening it isn't so easy: I had the key, you know." He brought a curious and delicately wrought skeleton from his pocket. "Tipped with platinum," he observed. "Rather a gem of a key, I think. You see, there must have been some action, even through the keyhole, or he wouldn't have used a metal of this kind. But the crew was rich in certain qualities, it seems, which I failed, stupidly, to recognise in my acquaintance with them. Both Pulz and Perdosa appear to have been handy men where locks were concerned. First Pulz sneaks down and has his turn at the chest. He gets it open. Small profit for him in that: the next we know of him he is scandalising Handy Solomon by having a fit on the deck."

"That is what I couldn't figure out to save my life," said Slade eagerly.

"If you recollect, I told you of the Professor's plunge in the cold spring, in a sort of paroxysm, one day," said Darrow. "That was the physiological action of the celestium. At other times, I have seen him come out and deliberately roll in the creek, head under. Once he explained that the medium he worked in caused a kind of uncontrollable longing for water; something having none of the qualities of burning or thirst, but an irresistible temporary mania. It worried him a good deal; he didn't understand it. That, then, was what ailed Pulz. When he opened the chest there was, as I surmise, a trifling quantity of this stuff lying in the inner lid. It wasn't the celestium itself, as I imagine, but a sort of by- product with the physiological and radiant effects of the real thing, and it had been set there on guard, a discouragement to the spirit of investigation, as it were. So, when the top was lifted, our little guardian gets in its work, producing the light phenomenon that so puzzled Slade, and inspiring Pulz with a passion for the rolling wave, which is only interrupted by Handy Solomon's tackling him. As he fled he must have pulled down the cover."

"He did," said Slade. "I heard the clang. But I saw the radiance on the clouds. And the whole thickness of a solid oak deck was in between the sky and the chest."

"Oh, a little thing like an oak deck wouldn't interrupt the kind of rays the doctor used. He had his own method of screening, you understand. However, this inconsiderable guardian affair must have used itself up, which true celestium wouldn't have done. So when Perdosa sets his genius for lock-picking to the task, the inner box, full of the genuine article, has no warning sign-post, so to speak. Everything's peaceful until they raise the compound-filled hollow layer of the inner cover, which serves to interrupt the action. Then comes the general exit and the superior fireworks."

"That's when the rays ran through the ship," said Slade. "It seemed to follow the deck-lines."

"The stuff had a strange affinity for tar," said Darrow. "I told you of the circle of fire about Professor Schermerhorn's waist the day he gave me such a scare. That was the celestium working on the tarred rope he wore for a belt. It made a livid circle on his skin. Did I tell you of his experiments with pitch? It doesn't matter. Where was I?"

"At the place where we all jumped," said Slade.

"Oh, yes. And you dove into the small boat, trying to reach the water."

"Wait a bit," said Barnett. "If that was the exhibition of radiance we saw, it died out in a few minutes. How was that? Did they close the chest before they ran?"

"Probably not," replied Darrow. "Slade spoke of Pulz taking to the maintop and being shaken out by the sudden shock of a wave. That may have been a volcanic billow. Whatever it was, it undoubtedly heeled the ship sufficiently to bring down both lids, which were rather delicately balanced."

"Yes, for Billy Edwards found the chest closed and locked," said Barnett.

"Of course; it was a spring lock. You sent Mr. Edwards and his men aboard. No such experts as Pulz or Perdosa were in your crew. Consequently it took longer to get the chest open. When at length the lid was raised, there was a repetition of the tragedy. Mr. Edwards and his men leaped. Probably they were paralysed almost before they struck the water. Your bos'n, whom Slade picked up, was the only one who had time even to grab a life preserver before the impulse toward water became irresistible. There was no element of frig............