Show shouting from post to post to relay messages until about 60 years year sago ago almost no use was made for the purposes of communication at a distance of the simplest most direct and most effective medium for the expression and transmission of thought I 1 the human voice true it is recorded that when the persians invaded greece in B C they established a line of sentinels who by shouting from post to post relayed messages between athens ns and susa in 48 hours the ancient bauls used a similar communication muni cation system for military purposes alexander the great is said to have employed a gigantic speaking trumpet which could project the voice voice a distance of 12 miles other devices similar to the megaphone and still others following the principle of the speaking tube have been used from time to time but all of these were relatively ineffective in extending the normal range of the voice not until the invention of the telephone in 1876 was the spoken word set free from the limitations ot of distance |