The first automatic radiobeacon in the United States began service in 1928. Radiobeacons are still in use today, although most have recently been decommissioned as improved electronic navigational aids have become available. An automatic time clock for operating electric range lights came into use in 1926, and by 1933, a photo electric-controlled alarm device had been developed to check the operation of the unwatched electric light. A lightship staffed by remote control was equipped by the Lighthouse Bureau in 1934. It included a light, fog signal, and radiobeacon, all controlled by radio signals. A battery-powered buoy which gradually replaced the older acetylene buoys, was introduced in 1935. Because of the technological improvements mentioned above, and in particular the radio beacon direction finder, the United States rose from sixth in shipping safety in 1920 to second in 1935, with only the Netherlands holding a better safety record.