Popular science -- the origin of mechanical clocks
Clocks can keep the results of time measurement, which is called "punctuality", and the tool of punctuality is usually the clock. After water clock and sand clock, people invented mechanical clock. From ancient wall clocks to delicate quick pendulum watches, there is a pendulum. Only a moving pendulum can indicate the time and make the clock go accurately.
Who invented pendulum? How was the first clock in the world to measure time with the vibration of a pendulum made? Let's get to know it with Xiaobian~
In 1583, in Pisa, Italy, a young man named Galileo went to church. He saw a copper lamp hanging under the roof by a rope, which was blown by the wind, and the lamp slowly swung back and forth. This swing is a common natural phenomenon, which has not attracted people's attention for a long time, but Galileo grasped this phenomenon: the swing is stable and uniform, and is the time of each swing the same? There was no clock at that time, so it was impossible to compare.
Later, in class, the teacher said, "generally speaking, the number of people's pulse is stable." This gave Galileo enlightenment: can we use the pulse to measure the swing period of the chandelier? When he went to church again, he silently counted the number of times by pressing his pulse with his fingers, and carefully observed the swing of the chandelier. He found that the time of the light swing was always the same. Although the amplitude of the swing will become smaller and smaller until it is completely stationary, the time taken for one swing does not become smaller. The experiment also found that the shorter the rope, the shorter the time of each swing. He finally found that the swing period of the pendulum has nothing to do with the amplitude, which is the isochronous law of the swing of the simple pendulum.
Galileo wanted to use a pendulum to indicate time. Because of the prevalence of religion in those days, the dissemination of scientific truth was imprisoned, and Galileo failed to do so.
In 1656, Huygens, a Dutch scientist, made further research on the isochronous law of a single pendulum discovered by Galileo and created the world's first clock that measured time with the vibration of the pendulum. This pendulum clock is roughly divided into two structures: the swinging part and the counting part. The counting part usually adopts pointer and dial digital display, and the mechanical clock made by using this principle has been used in the world for more than 300 years.
Why does the pendulum swing? This is related to the gravity of the earth. When the pendulum loses balance in position, gravity and the tension of the line are not in a straight line, resulting in a force that makes the pendulum return to the balanced position, causing the pendulum to swing. The period of a simple pendulum is related to the attraction of the earth. Therefore, a pendulum can be isochronous only if it is in the same place and the attraction of the earth's center is the same.
Early mechanical clocks were made of relatively large ones. There is a huge clock in the parliament building in London, England - Big Ben. Big Ben has four clock faces, one on each side of the quadrangular tower. The diameter of each clock face is 8 meters, its minute hand is 3.5 meters long, the number on the clock face is 75 cm high, and the pendulum weighs 200 kg.
In order to improve the clock and make it more delicate, people thought of an elastic object, because the swing of a simple pendulum is a kind of vibration, and the spring can also vibrate freely. People found that if a certain spring is constructed, its frequency is always constant. According to this principle, the balance wheel hairspring is made. The hairspring is a spiral spring, one end is installed on the pendulum shaft, the other end is installed on a fixed metal sheet, The balance wheel is pushed to the left or right, and the hairspring is sometimes rolled tightly and sometimes loosened. With the balance wheel hairspring, people made pocket watches and watches.