Heidegger notes that the disparity between two alike objects (simliar in function) from the technological time gap between them. For example, he states "A radar station is of course less simple than a weather vane," inferring to the huge technological gap between the two alike metrological instruments. More importantly, he states that that in order for the construction of a radar station, technological developments and production must mesh together. He maintains that a sawmill and hydroelectric plant are different technologically, but their purpose to generate hydropower via a large turbine influenced by water current is virtually unchanged throughout the centuries.