The Coming of Age of Long-Distance Wireless Telegraphy and some of its Scientific Problems1

Abstract

IT is just twenty-one years since Senatore Marconi began to equip with wireless apparatus a station at Poldhu in Cornwall for the first attempt at transatlantic wireless telegraphy. Until then only appliances of a laboratory type had been used to signal to distances of about 100 miles. This first attempt at long-distance working necessitated the conversion of these appliances into engineering plant employing large power. Although at first the spark system, in which the electric waves are generated by discharges of large electric condensers, was used at Clifden in Ireland and Glace Bay in Nova Scotia, and developed by Senatore Marconi ultimately into the timed spark continuous wave system in the great wireless stations at Carnarvon, N. Wales, New Jersey, U.S.A., and Stavanger, Norway, the usual practice of late years has been to employ either the Poulsen electric arc generator, the high-frequency alternator, or, more recently, the thermionic valve generator. At the recently projected gigantic wireless stations, such as those at St. Assise, near Paris, and Long Island, U.S.A., the high-frequency alternators of LatourBathenod and of Alexanderson are to be employed. At the first Imperial wireless station at Leafield, Oxfordshire, erected by the General Post Office to correspond with one at Cairo, the Elwell-Poulsen arc generator is used. The arc generator has, however, the disadvantage that the waves emitted are a mixture of wave-lengths, and not a single pure wave or monochromatic. Important installations of large valve transmitters have recently been made by the Marconi Wireless Telegraph Company at Clifden, Ireland, and at their great Carnarvon station in N. Wales.