accurate measurements of distance , mass and so on were made much before accurate measurement of time became possible why?
the swing of a pendulum gradually decreases with time . however , even then it is regarded as a reliable time keeping device
Length and mass were the earliest measurements made mankind.Measurement of time was done in terms of distance and mass.Position of sun, moon and star give idea of days, months and years.Now a days atomic clock measures time accurate upto nano seconds by measuring waves emitted by Cesium clock in terms of speed of light and frequency.So we can say that over the time improvements, the measurement of distance and mass help in measuring time with more accuracy and precision.
Any phenomenon that repeats itself regularly can serve as a measure of time.A pendulum is ideally free from damping, it swings continuously without changing its time period.In this, one second was defined as the time taken by a simple pendulum of length one meter in going from one extreme position to other extreme position. So pendulum was considered as a time keeping device.