Lake Titicaca is the largest body of water on the surface of the globe at an elevation exceeding twelve thousand feet, and probably the most elevated lake navigated by steam. Before the introduction of steamboats the only mode of water transit was upon balsas, or rafts, made of the tortora or rushes already mentioned; the lake is liable to be swept by sudden winds, and the party who ventures upon it in one of these frail craft runs a good chance of a wetting. The steamboats have not by any means driven the balsa from the lake, but they have rendered it less obligatory on strangers to trust themselves to its limited accommodations and its certainty of discomfort. It was after dark when the steamer reached Titicaca Island, and ran into a little bay where there was a shelter from the wind. As nothing could be seen on the land, during the night, it was decided to sleep on board, and make an early visit to the shore in the morning. The Doctor and the youths made a hearty supper from their provisions and some hot tea, and then spread their beds on the floor of the cabin, which had no berths or other sleeping accommodations. Several balsas came from shore in the morning, and afforded means for landing on the sacred island of Peru. Titicaca Island is about six miles long by four in width; it is high and rugged, and the shores are deeply indented in many places. It contains the ruins of a Temple of the Sun, a palace of the Incas, and several other buildings, which have sadly gone to decay. Frank and Fred ascended the steep acclivity at the landing-place, closely followed by the Doctor, and were soon at a little village near by, where they obtained a guide to show them through the ruins. [Illustration: CLOSED DOORWAY, TITICACA ISLAND.] Near the village there were the remains of a building; tradition says it was the place where pilgrims to the sacred islands were required to remain for several days after their arrival in order to go through certain ceremonies of purification. There was a broad platform in front of the building, the latter being divided into two parts, measuring thirty-five feet one way by twenty-seven the other. The upper part of the walls had fallen, but the lower portion was well preserved. The walls were of limestone, carefully cut, and set in tough clay, which seems able to resist the ravages of the climate. [Illustration: PALACE OF THE INCA.] About half a mile from the landing-place is "the Palace of the Inca" on a cliff overlooking the lake. Its walls are broken at the top, but enough remains to show the style of the ancient architecture, and the forms of the windows and doorways. Frank wondered that the earthquakes had not destroyed the palace long ago; the Doctor said this part of Bolivia is rarely visited by disturbances of the earth, the whole basin of Titicaca being singularly free from them. The home of the South American earthquake is practically confined to the western side of the Andes.