【明報專訊】Before the development of the electric telegraph (電報) in the 19th century revolutionised how information was transmitted across long distances, ancient civilisations such as those in China, Egypt and Greece used drumbeats (鼓聲) or smoke signals to exchange information between far-flung (遙遠的) points. However, such methods were limited by the weather and the need for an uninterrupted line of sight between receptor points.