What was the fusee that brought about such a change? Not much to look at, surely—merely a short cone with a spiral groove running about it, and a cord, or chain, wound in this groove and fastened at the large end of the core. Its principle and its action were very simple, and that is why it was a great invention. Some one has said that anyone can invent a complicated machine to do a piece of work, but it takes real brains to make a _simple_ machine _that will do the same work_. [Illustration: _Stackfreed_ _Mainspring Barrel and Fusee_] The shaft of the fusee was attached to the great wheel which drove the gears, and the other end of the cord was fastened to the mainspring barrel. This is the way in which it worked: The mainspring slowly turned the barrel; this gradually unwound the cord from the fusee and caused the fusee to turn. When the fusee turned, the wheels also were forced to turn, and the watch was running. At the start, the cord would unwind from the small end where the leverage was least, but as the tension of the mainspring grew slowly less, the leverage of the cord grew slowly greater and, consequently, the power applied to the wheels was always of the same degree of strength. This invention gave a great impulse to Swiss watchmaking; several centuries later it worked to the disadvantage of English manufacturers, for they continued to use it after other countries had found still better methods of power equalization. The fusee was invented about the year 1525, at a time when the world was fairly alive with new ideas. People in Europe were just beginning to realize that they were living on a sphere and not upon a flat surface, and that there was a vast new land on the other side of the ocean. Columbus had crossed the Atlantic but a few years before and now explorers were making new voyages of discovery in every direction. Printing, invented by Gutenberg, about a century before, was becoming common enough to be a real power in the world, bringing the thoughts of men before the eyes of thousands without the slow and expensive process of hand-copying. The first printed copy of the Bible had made its appearance and Caxton had set up his first printing-press—all within the lifetime of people then living—and printing shops were being established in many places. Many people were learning to read—a thing that could be said of very few in the Middle Ages. They were finding out something about the wonderful forgotten civilization of ancient times. Everywhere people's minds were stirring. We call it the time of the _Renaissance_, or the _rebirth_ of civilization, but in some respects it was more like the awakening of the world after a long sleep. Just as a person on waking looks first at his clock or watch, so now the world, preparing to be busy and modern, needed some better means of telling time. It therefore was both natural and necessary that the watch should have received such a great improvement as the fusee at just this period.