The Naval Observatory time‐service has undergone in recent years an interesting development and expansion. This has been brought about by a demand for increased accuracy in the time‐signals. The task of sending regular signals of sufficient accuracy to meet the needs of navigation and every‐day life is, of course, relatively simple. When, however, the signals are to be used by longitude‐parties and radio laboratories and are to be subjected to comparison with similar signals emanating from foreign observatories, the highest obtainable degree of accuracy becomes de