About the middle of the thirteenth century there began to appear on the decks of vessels almost everywhere in Europe, a little instrument that is of the greatest importance in the history of the boat. This was the _mariner's compass_. The use of the magnetic needle was known in China (Fig. 13) a thousand years before it was known to the Europeans, but in this, as in many other instances, the Chinese did not profit by their knowledge. Sailors have always sailed at night by the North star; but before the use of the compass was understood they could little more than guess their way when the night was dark and the stars could not be seen. With a mariner's needle on board they can tell the direction they are going no matter how dark the night. We can easily understand that sailors prized very highly the discovery of the compass. With the appearance of this faithful guide they became bolder and bolder and were soon venturing out upon the trackless expanse of the ocean. It was the compass that led to the discovery of the new world, for without it no sailor could have held his course due west long enough to reach the American coast. After men had learned to carry their burdens on the broad back of the ocean, boat-building took on new life. All the great nations of Europe wanted a share in the new world that had just been found; but no nation could hope to profit greatly by the discovery of Columbus if its vessels were not swift and strong. So there arose a grim contest for the mastery of the Atlantic, just as in ancient times there had been a struggle for the mastery of the Mediterranean. Spain, France, Portugal, Holland and England all joined in the battle. When we see the kind of boats she sent out upon the oceans we are not surprised that England won. Compare the heavy, angular galley of the first century with the graceful ship of the sixteenth century and we see at once the progress the boat made in the Middle Ages (Fig. 14). [Illustration: FIG. 14.--THE GREAT HARRY.] The log, the raft, the galley, the sailing-ship, these were the steps in the development of the boat up to the end of the seventeenth century. In the eighteenth century another step was taken. You remember that in that century inventors were everywhere trying to make a steam carriage. They were at the same time trying to make a steam boat. Their efforts to use steam to drive boats were rewarded with success earlier than were their efforts to use it to draw carriages. This was to be expected. Boat-building has always moved along faster than carriage-building. Men were gliding about in well-built canoes before they had even the clumsiest of carts. The Londoners who gazed with admiration upon the _Great Harry_ as it sailed on the Thames, had never seen as much as a lumbering coach. And so with the steamboat; it had crossed the Atlantic before the locomotive could carry passengers from one town to the next.