Why do clocks slow down over a long period of time?
In addition to serious magnetic this situation will be faster, mechanical clocks and watches for a long time, most of the situation will happen to slow down.The reason for the slowdown is that the lubricating oil of the movement becomes more and more viscous over time, and the dust inside the movement mixes with the lubricating oil to form the so-called "slime". Because the effect of lubrication is reduced, the surface naturally slows down.