Initially, the day and night cycle was used as a reference.
Attempts to divide the day into smaller periods of time required measuring devices.
Instrumentation:
1. Sundial
2. Water clock
3. Hourglass
4. Pendulum clock
5. Electric clock
6. Quartz watch.
7. Atomic clock
This is a simple list of devices for measuring time in descending order of implementation of the invention.