What happened 1581 AD in undefined

Germany would enjoy relative peace for the next six decades. On the eastern front, the Turks continued to loom large as a threat, although war would mean further compromises with the Protestant princes, and so the Emperor sought to avoid it. In the west, the Rhineland increasingly fell under French influence. After the Dutch revolt against Spain erupted, the Empire remained neutral, de facto allowing the Netherlands to depart the empire in 1581, a secession acknowledged in 1648. A side effect was the Cologne War, which ravaged much of the upper Rhine.

In 1581, when Galileo was studying medicine, he noticed a swinging chandelier, which air currents shifted about to swing in larger and smaller arcs. To him, it seemed, by comparison with his heartbeat, that the chandelier took the same amount of time to swing back and forth, no matter how far it was swinging. When he returned home, he set up two pendulums of equal length and swung one with a large sweep and the other with a small sweep and found that they kept time together. It was not until the work of Christiaan Huygens, almost one hundred years later, that the tautochrone nature of a swinging pendulum was used to create an accurate timepiece.