Now, on this day two weeks after they'd left the island, Miran was shooting the sun, and Green was waiting until he was through, so he could check on him. If his calculations were correct the yacht should be directly east of Estorya two hundred miles. If they maintained their average rate of twenty-five miles an hour they'd reach the windbreak in a little over eight hours. The fat merchant quit looking through the eyepiece of his instrument and walked to the cockpit where his charts and papers were. Green took the sextant from him and made his own observations, then checked with Miran in the narrow and crowded cockpit. "We agree," said Green, indicating with the pencil tip a round scarlet spot on the chart. "We should be sighting this island within four hours." "Yes," replied Miran. "That is an old landmark. It has been there a hundred miles due east of Estorya since before my grandfather's time. It was once a roaming island, but it long ago quit moving and has stayed in that one spot. That is nothing unusual. Every captain knows of these fixed islands scattered all over the Xurdimur, and every now and then we have to add a new red mark to our charts because one of the roamers has settled down." He paused, then added a statement that set Green's heart to beating fast. "The unusual thing about this island is that it did not stop of its own accord. It was halted by the magic of the Estoryans, and it has been kept in that one place ever since by their magic." "What do you mean?" asked Green, eagerly. Miran's round, pale-blue eye stared at him blankly. "What do you mean what do I mean? I mean just what I said, nothing more." "I mean, what magic did they contrive to halt this roamer?" "Why, they put up certain peculiar towers in its path, and when the island began going backwards to get out of the trap and go around it, they moved other towers to block its retreat. These towers moved fast on many well-greased wheels. Once the circle was completed the island couldn't move. Nor has it been able to move since." "These towers intrigue me. How did the Estoryans know how to halt these islands? And if they've succeeded with one, why not with the others?" "I do not know. Perhaps because the towers are huge and costly and don't move too fast. Perhaps it is not worthwhile to the Estoryans to capture many. As for their knowledge, I think they got it from their ancestors. It was their great-great-great-and-then-some-grandfathers who originally built Estorya in the middle of the plain and protected it from being crushed by these islands by placing these many towers all around their city. But it cost them much wood and time, and perhaps they lost interest after that." Miran indicated a castle inked in beside the red spot.