When they made the first clocks, how did they know whether they were accurate?

Question

They had nothing to compare the clocks against, and I don’t think the stars and the sun would have made an useful target for comparison.

In: 17

Answer 1

With a stationary (and properly filtered!) telescope you can quite easily track the sun’s motion. A clock could be adjusted to show noon at the precise momemt the edge or middle of the sun touches the crosshair in a properly oriented telescope.

You could check again the next day without moving the telescope and compare times.