"It was Birger Jarl who built the first walls and towers to protect the city," spoke Gerda. "I remember learning it in my history lesson." "Yes," her father replied; "good old Earl Birger, who ruled the Swedes in the thirteenth century, saw how important such fortifications would be, and so he locked up the Mälar Lake from hostile fleets by building walls and towers around one of the islands and making it his capital." "There is an old folk-song in one of my books which always reminds me of the Vikings," said Birger. "Let us hear it," suggested his father, and Birger repeated:-- "Brave of heart and warriors bold, Were the Swedes from time untold; Breasts for honor ever warm, Youthful strength in hero arm. Blue eyes bright Dance with light For thy dear green valleys old. North, thou giant limb of earth, With thy friendly, homely hearth." "There is another stanza," said Gerda. "I like the second one best," and she added:-- "Song of many a thousand year Rings through wood and valley clear; Picture thou of waters wild, Yet as tears of mourning mild. To the rhyme Of past time Blend all hearts and lists each ear. Guard the songs of Swedish lore, Love and sing them evermore." "Good," said Lieutenant Ekman; "isn't there a third stanza, Birger?" But Birger was at the other end of the boat. "Come here, Gerda," he called. "We can see Waxholm now." Then, as the boat slipped past the great fortress and began to thread its way in and out among the islands in the fjord, the twins stood at the rail, pointing out to each other a beautiful wooded island, a windmill, a rocky ledge, a pretty summer cottage nestling among the trees, a fisherman's hut with fishing nets hung up on poles to dry, an eagle soaring across the blue sky, or a flock of terns flying up from the rocks with their harsh, rattling cry. There was a new and interesting sight every moment, and the sailors in their blue uniforms nodded to each other with pleasure as Gerda flitted across the deck. "She is like a little bluebird," they said; and like a bird she chirped and twittered, singing snatches of song, and asking a hundred questions. "I like those old fancies that the Vikings had about the sea and the sky and the winds," she said at last, stretching her arms wide and dancing from end to end of the deck. "They called the sea the 'necklace of the earth,' and the sky the 'wind-weaver.'" "I wish I had the magic boat that Loki gave to Frey," answered Birger lazily, lying flat on his back and looking up into the "wind-weaver." "If I had it, I would sail over the whole long 'necklace of the earth,' from clasp to clasp." But Gerda was already out of hearing. She had gone to sit beside her father and watch the course of the boat through the thousands of rocky islands that stud the coast.