For example, see D. Landes, Revolution in Time: Clocks and the Making of the Modern World, Harvard University Press, Cambridge, Mass., 1983.
Our current standards of time are no longer precisely associated with the movements of the Earth around the sun or the turning of the Earth but on atomic oscillations at the quantum level which define the second. This standard, in turn, determines other measuring yardsticks such as those for distance which derive from the speed light travels in a second.
Once again, however, those wanting an in-depth discussion of such issues would probably wish to try elsewhere. For example, an excellent recent compilation is R. Flood and M. Lockwood (eds), The Nature of Time, Basil Blackwell, Oxford, 1986.