 They were used worldwide in astronomical observatories, naval observatories, and as primary standards for electrical time dissemination services, which delivered time signals by telegraph wire.Riefler clocks had internal switch contacts for this purpose, which delivered a 1 Hz time signal to external equipment.The first time standard for the United States, provided by the Bureau of Standards (now NIST), was from 1904 to 1929 generated by Riefler clocks.