World-wide Telephony

Abstract

AT the International Electrical Congress recently held in Paris, several important papers were read on telephony. B. Gherardi and F. B. Jewett discussed ‘world telephony’. The history of the subject illustrates how great discoveries occur at various intervals of time. Each of them causes a revolution in practice and between the intervals the process of applying the new inventions goes on continuously in the economic field. Such epoch-making discoveries were the invention of the thermionic tube, the permalloy series of nickel-iron alloys, and the discovery of paragutta. The use of paragutta has reduced the transmission losses to one-thirtieth of their former value. Many difficulties remain for engineers to overcome. For telephony between North America and Europe, ‘long’ radio waves are most suitable, but there is the fundamental restriction that there are in practice only twenty ‘ways’ available owing to the limited breadth of the band of frequencies that can be utilised. With ‘short’ wave-lengths, the best wave-length to use depends on the hour of the day and the season of the year. Hence three wave-lengths are usually assigned to each circuit, and this limits the number of ways. Short-wave transmission is still in the first stage of its evolution; interruptions due to the vanishing of signals and to magnetic storms occur not infrequently, especially when the waves go through polar regions. The difference in local time between many large towns is a great inconvenience. There may be no overlapping in time between their working days. The language difficulty, although of less importance, is still a hindrance to progress. Many conversations are held between speakers in a language which neither knows well. In this case it is necessary that the clarity of the transmission be much better than when each is speaking his own tongue. Technical progress has now made possible communication between countries and continents. Whether this will be a boon to humanity or not depends on the nature of these communications.