It didn't take Greta and Anna long to climb the narrow, winding stairs. From the top of the lighthouse they could see for many miles over the ocean and over the land. Heavy waves beat upon the beach, and even as they looked, the sand hills kept shifting, for the wind from the North Sea was very strong. Not far away was the harbor, and in its quiet waters some of the fishermen had fastened their sailboats. Near by they had hung up their nets to dry. Each net was carefully spread over a rope that was fastened to stakes in the ground. Other fishing boats, with sails full spread, were far out at sea. [Illustration: THERE ARE MANY BOATS IN THE HARBOR] "Anna, do you see those people way down the beach? I wonder what they are looking for." Greta pointed to two women who were evidently searching for something along the shore. "I haven't any idea. Shall we go help them with their search? Look, Greta. Your father is motioning to us to come down. I think Chouse wants us, too." Greta's father had to go on to the next village, but he told the girls that they could stay here until he came back. "Chouse will take good care of you while I'm gone," he said, "that is, if he doesn't run off and get into some kind of mischief himself." Greta and Anna were curious about the women they had seen down the beach, so they decided to join them. With Chouse jumping and barking at their heels, they ran along the water's edge. The tide was coming in, and every now and then a large wave almost caught them. As they went farther from the harbor, they found more and more sand dunes: gently rolling hills with long blades of grass poking up here and there through the sand. Along this part of the beach there were many summer cottages, with fences around them to keep the sand from covering them completely. [Illustration: ALMOST EVERY FARM HAS ITS WINDMILL] "Have you lost something?" asked Anna as they came near the two women. "We'll be glad to help you look for it." "No, we haven't lost anything," answered one of the women. "We thought we might find some amber along the beach." "Amber?" asked Greta in surprise. "I didn't know it was found here." "Oh, certainly. We have often found some very fine pieces of amber on this very beach." "Is amber a stone?" asked Greta. "Of course I know what it looks like, but what is it made of?" "It has taken thousands of years to form the lovely clear yellow material that we call amber," explained the second woman. "It was once the sticky, yellowish fluid given off by the pine trees. As time went by, those trees were buried under the ground or under the water. The sticky fluid gradually became hard as stone. It is those stone-like pieces that we sometimes dig up along the beach of the North Sea." [Illustration: CHOUSE LIKES TO PLAY] "They are very valuable, aren't they?" asked Anna. "Yes, some of them are. Those that are perfectly clear and have no flaws always bring a good price." "We'll help you look," said Greta.