An early report on `` The International Radio-Telegraphic Convention '' in the January 12 , 1907 Electrical World said that `` Vessels in distress use the special signal , SOS , repeated at short intervals . '' An early report on `` The International Radio-Telegraphic Convention '' in the January 12 , 1907 Electrical World stated that `` Vessels in distress use the special signal , SOS , repeated at short intervals . ''