The boys could not distinguish one tower from another at that distance. "What kind of mill is it?" asked Will. "A flour-mill." "Are all these flour-mills?" "Oh no! There are saw-mills, colza-oil mills, mustard-mills, flax-mills, and other kinds I don't remember." It was now nearly supper-time, and the little group returned home. The next morning, the whole party--four grown-up people, four youngsters, and four boats (the "Wilhelmina," the "Gouda," the "America," and the "Columbus")--were all taken up the Zaan River in a row-boat for about three miles, and then up a small stream to the mill where they were to spend the day. The first thing in order was the inspection of the mill, which was unlike anything they had ever seen in America. The tower was of brick. It was three stories high, over a basement. In the basement were the stables and wagon-house; over this was the granary, and flour and meal store; above this were the bolting-rooms, the ground wheat running through spouts to the store-rooms below. On the next floor above were the mill-stones, and the simple machinery that turned them. And, above all, at the very top of the tower, was the main shaft of the great wings outside. These wings caught the winds, and compelled them to work the machinery with such force as to make the strong tower tremble. There were balconies around the first and third stories of the mill. It was quite a picturesque object standing among low trees on a pretty, quiet stream, the banks of which were higher and more uneven than was usual in that part of the country. The miller lived in a small house near the mill with his wife and his little daughter Hildegarde, the latter of whom was near Greta's age. The boys did not take as much interest in the miller's house as their parents took; but when they were shown into a large outer room, and were told it was the cow-stable, they had no words with which to express their astonishment. They would have said it was the show-room of the place. There was not a speck on the whitewashed walls; the pine ceiling was so clean it fairly glistened; there were crisp, white muslin curtains at the windows. The raised earthen floor was covered with pure white sand, arranged in fancy designs. There were some small round tables standing about, and on them were ornaments of china and silver, and a variety of knick-knacks. During the summer the cows were in the pasture day and night, but in the winter they occupied this room. Then the tables were removed, but the place was kept very neatly. This was necessary, for the stable adjoined the house, and the party passed into the barn through a door in the cow-stable. All except the two boys. Will hung back and motioned to Martin not to go into the barn. "I am tired of this sort of thing," he said. "Let us go and sail our boats." "Very well," said Martin, "I'll call the girls."