During the French Revolution French postal services progressively became a fully public service. Directors of post offices lost their privileges in 1789 and their position became subject to universal suffrage. The "ferme générale" was abolished two years later and post offices started to be directly administered by the state. As a reaction to commonplace opening of letters by the royal authorities, an oath of confidentiality became compulsory for post employees in 1790. The first French mail coach appeared in 1793 and the first telegram in the world was delivered in 1794 with the Chappe optical transmitter on the Paris-Lille line.