There was a section on my textbook on history of theories of sun's energy source.
It talks about how the Meteorite Theory was dismissed, as it would decrease the period of Earth's orbit by 2 seconds per year due to increased mass of the Sun.
This theory was dismissed due to disagreeing with observation. And the textbook says the change in period is "easily measurable"
My question is how is 2 seconds difference easily measurable in Nineteenth Century?