The white man who had helped to carry the chest was now kneeling, busied at some work, though what it was Tom at first could not see. He was whittling the point of a stick into a long wooden peg, and when, by-and-by, he had finished what he was about, he arose and stepped to where he who seemed to be the captain had stuck his cane upright into the ground as though to mark some particular spot. He drew the cane out of the sand, thrusting the stick down in its stead. Then he drove the long peg down with a wooden mallet which the negro handed to him. The sharp rapping of the mallet upon the top of the peg sounded loud in the perfect stillness, and Tom lay watching and wondering what it all meant.
The man, with quick-repeated blows, drove the peg farther and farther down into the sand until it showed only two or three inches above the surface. As he finished his work there was another faint flash of light, and by-and-by another smothered rumble of thunder, and Tom as he looked out towards the westward, saw the silver rim of the round and sharply outlined thundercloud rising slowly up into the sky and pushing the other and broken drifting clouds before it.
The two white men were now stooping over the peg, the negro man watching them. Then presently the man with the cane started straight away from the peg, carrying the end of a measuring-line with him, the other end of which the man with the plaited queue held against the top of the peg. When the pirate captain had reached the end of the measuring-line he marked a cross upon the sand, and then again they measured out another stretch of space.
So they measured a distance five times over, and then, from where Tom lay, he could see the man with the queue drive another peg just at the foot of a sloping rise of sand that swept up beyond into a tall white dune marked sharp and clear against the night sky behind. As soon as the man with the plaited queue had driven the second peg into the ground they began measuring again, and so, still measuring, disappeared in another direction which took them in behind the sand-dune, where Tom no longer could see what they were doing.
The negro still sat by the chest where the two had left him, and so bright was the moonlight that from where he lay Tom could see the glint of it twinkling in the whites of his eyeballs.