Measuring Time

Core concept

Historically, before modern clocks, people relied on natural events like the position of the Sun, or devices like a simple pendulum, whose regular back-and-forth swing (at a fixed time period for a given length) formed the basis of early mechanical clocks. Galileo first noted that a pendulum's swing period depends on its length, not its weight, a discovery that led to the invention of the pendulum clock, a major improvement in timekeeping accuracy.