When the boys left this Museum, they went to another and saw a wonderful collection of fossil animals, skeletons, birds, minerals, precious stones and other natural specimens, but as they were not learned men, they could only walk about and stare, enjoy the little knowledge of natural history they possessed, and wish with all their hearts they had acquired more. Even the skeleton of the mouse puzzled Jacob. What wonder? He was not used to seeing the cat-fearing little creatures running about in their bones--and how could he ever have imagined their necks to be so queer? Besides the Museum of Natural History, there was Saint Peter's Church to be visited, containing Professor Luzac's Memorial, and Boerhaave's Monument of white and black marble, with its urn and carved symbols of the four ages of life, and its medallion of Boerhaave, adorned with his favorite motto "Simplex sigillum veri." They also obtained admittance to a tea-garden, which in summer was a favorite resort of the citizens, and passing naked oaks and fruit-trees, ascended a high mound which stood in the centre. This was the site of a round tower now in ruins, said by some to have been built by Hengist the Anglo Saxon king, and by others to have been the castle of one of the ancient counts of Holland. As the boys walked about on the top of its stone wall, they could get but a poor view of the surrounding city. The tower stood higher when, more than two centuries ago, the inhabitants of beleaguered Leyden shouted to the watcher on its top their wild, despairing cries--"Is there any help? Are the waters rising? What do you see?" And for months he could only answer--"No help. I see around us nothing but the enemy." Ben pushed these thoughts away; and resolutely looking down into the bare tea-garden, filled it in imagination with gay summer groups. He tried to forget old battle-clouds, and picture only curling wreaths of tobacco-smoke, rising from among men, women and children enjoying their tea and coffee in the open air. But a tragedy came in spite of him. Poot was bending over the edge of the high wall. It would be just like him to grow dizzy and tumble off. Ben turned impatiently away. If the fellow with his weak head knew no better than to be venturesome, why, let him tumble. Horror! what meant that heavy, crashing sound? Ben could not stir. He could only gasp: "Jacob!" "Jacob!" cried another startled voice and another. Ready to faint, Ben managed to turn his head. He saw a crowd of boys on the edge of the wall opposite--but Jacob was not there! "Good Heaven!" he cried, springing forward, "where is my cousin?" The crowd parted. It was only four boys, after all. There sat Jacob in their midst, holding his sides and laughing heartily.