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An Encyclopedia of the History of Technology part 74

An Encyclopedia of the History of Technology part 74. This one of a kind encyclopedia presents the entire field of technology from rudimentary agricultural tools to communication satellites in this first of its kind reference source. Following an introduction that discusses basic tools, devices, and mechanisms, the chapters are grouped into five parts that provide detailed information on materials, power and engineering, transportation, communication and calculation, and technology and society, revealing how different technologies have together evolved to produce enormous changes in the course of history | PART FOUR COMMUNICATION AND CALCULATION Figure 15.2 Three stages in the evolution of the telegraph a Chappe s 1794 semaphore b von Soemmering s 1809 electrolytic telegraph. A station agent telegraphed the page number with his first signal and the number of the word on the page with his second. Phrase and place-name vocabularies each again of 92 by 92 items were developed to distinguish them an initial signal indicated the code the second the page and the third the item on the page. No public excitement over the semaphore system occurred until 1 September 1794 when Condé was recaptured. The Convention then ordered the extension of the line from Lille to Ostend and a second line to be built to Strasbourg which was completed in 1798 with 46 towers at a cost of 176 000 francs. Despite the practical success of these telegraph lines they did not bring in revenue but rather entailed great expense maintenance and service in the eighth year of use cost 712 INFORMATION Figure 15.2 c Cooke and Wheatstone s 1837 5-needle telegraph. 434 000 francs. Napoleon losing enthusiasm for the venture reduced the appropriation to 150 000 francs a year and cancelled a planned Paris-Lyon line. Claude Chappe thought that his system might benefit business as well as give an advantage in war. During the Restoration interest in the telegraph increased and Chappe s dream was at last realized but he committed suicide in 1805 despondent over the slow progress and suffering from bladder trouble. However his brothers continued to perfect the system Abraham worked at overcoming the fog problem anticipating British use of hydrogen fires during the Second World War. Semaphore systems remained in use well into the nineteenth century even after the electric telegraph was developed see p. 714 . Figuier writing in the 1860s claimed that aerial telegraphers could send a dispatch in two minutes from Lille to Paris a distance of 240km 150 miles requiring 22 stations in three minutes from Calais 270km 168 .