But however thick it was, he bet that anybody who had the tools, time and strength to excavate would find, embedded somewhere in that mass, several large dust-collectors. He didn't know what shape they'd take, because that would depend on the culture that had built them, and their tastes in decorations would differ from Green's multimillennia-later society. But if they had architectural ideas similar to present-day Terrans they would have constructed the collectors in the shape of busts or of animals' heads or even of bookcases with false backs of books filling them, books that would in reality have been both chargers and filters. The busts or books would have been pierced with many tiny holes, and through these holes the charged particles of dust would have drifted. Once inside the collectors, they would have been burned. Looking at the blank dirt before him, Green could see what had happened through the ages. Some part of the burning mechanism had gone wrong--as was the custom of mechanisms everywhere. But the charging effect had continued. And though the dust had piled up around the collectors, the extraordinarily powerful fields had continued to work even through the thick blanket. In the beginning, of course, their field could not have caused any human being harm. But these batteries must have been built to adjust to whatever demand was made of them, though their builders, of course, could have had no idea of how great that demand would some day be. Nevertheless it had come, and the batteries had been equal to it. By the time the savages had found this room they were blocked off by this imposing wall. Through the death of their fellows they had discovered that touching the wall caused a terrible discharge of electrostatic electricity. The rest of the apparatus for execution and the ritual that went with it was foregone and logical, religiously speaking. Green swore with frustration. How he would love to get through that dirt before another charge built up! On the other side must be another doorway, and it must lead to the fuel and control rooms for this whole island. If he could get inside and there figure out the controls, he'd turn this island upside down and shake off the man-eating monsters. There'd be no holding him then! He remembered the story of Samdroo, the Tailor Who Turned Sailor. The legend went that Samdroo, his 'roller wrecked upon just such a roaming island as this one, had wandered into just such a cave and through rooms like these. But he'd found no barrier of electrically charged dirt and had walked into a room which contained many strange things. One of them was a great eye that allowed Samdroo to see in it what was happening outside the cave. Another was a board which contained many round faces over which raced little squiggles and lines. Of course, the story had its own explanations for what these things were, but Green could hardly fail to recognize TV, oscilloscopes and other instruments.