"Observing the positions of the sun and moon, and of certain stars with relation to each other. That is done with the quadrant and sextant; and then they use a chronometer, or clock, that tells exactly what the time is at Greenwich. Then, you see, this book is full of figures that look like multiplication-tables; and with these figures they 'work out their position;' that is, they find out where they are. Greenwich is near London, and all the tables are calculated from there." "But suppose a sailor was dropped down here suddenly, without knowing what ocean he was in; could he find out where he was without anybody telling him?" [Illustration: WORKING UP A RECKONING.] "Certainly; with the instruments I have named, the tables of figures, and a clear sky, so as to give good observations, he could determine his position with absolute accuracy. He gets his latitude by observing the sun at noon, and he gets his longitude by the chronometer and by observations of the moon. When he knows his latitude and longitude, he knows where he is, and can mark the place on the map." Fred opened his eyes with an expression of astonishment, and said he thought the science of navigation was something wonderful. The others agreed with him; and while they were discussing the advantages which it had given to the world, there was a call that sent them on deck at once. "Land, ho!" from the lookout forward. "Land, ho!" from the officer near the wheel-house. "Land, ho!" from the captain, as he emerged from his room, just aft of the wheel. "Where away?" "Dead ahead, sir," replied the officer. "'Tis Fusiyama, sir." The boys looked in the direction indicated, but could see nothing. This is not surprising, when we remember that sailors' eyes are accustomed to great distances, and can frequently see objects distinctly long before landsmen can make them out. But by-and-by they could distinguish the outline of a cone, white as a cloud and nearly as shadowy. It was the Holy Mountain of Japan, and they recognized the picture they had seen so many times upon Japanese fans and other objects. As they watched it, the form grew more and more distinct, and after a time they no longer doubted that they looked at Fusiyama. "Just to think," Fred exclaimed, "when we left San Francisco, we steered for this mountain, five thousand miles away, and here it is, right before us. Navigation is a wonderful science, and no mistake." As the ship went on, the mountain grew more and more distinct, and by-and-by other features of Japanese scenery were brought into view. The western horizon became a serrated line, that formed an agreeable contrast to the unbroken curve they had looked upon so many days; and as the sun went down, it no longer dipped into the sea and sank beneath the waves. All on board the ship were fully aware they were approaching land. [Illustration: VIEW IN THE BAY OF YEDDO.]