International time signals. Transmitted by radio, this system of timing signals allowed synchronisation of clocks around the world using a standard repetition of signals over a four-minute time period. These four minutes are shown at top (numbers 56 to 59) and represent the four minutes preceding the previous signal. This system was used by the Bureau International de l'Heure (International Time Bureau), established at the Paris Observatory following an international conference in October 1912. Photograph published in 'La Telegraphie Sans Fil' (Wireless Telegraphy, 1914), by the French geophysicist Alphonse Berget (1860-1934).