In Retrospect

Radio Record, Volume II, Issue 16, 2 November 1928, Page 4

In Retrospect

1831-Faraday succeeded in obtaining electrie currents by Moving’ pa. Wire across a magnetic field, 1864--Clerk-Maxwell investigated ‘the fundamental nature of magnetism and electricity and predicted the possibility. of producing electro-magnetic waves in the ether. : , 1888---Hertz succeeded in producing such waves. 1889-Lodge invented the coherer and discovered the principles of electric tuning. 1897-Marconi invented the elevated transmitting and receiving aerial, 1901-First wireless signals sent across the Atlantic. 1904-Fleming invented the twoelectrode valve. 1906-Dunwoody discovers the rectifying action of -carborundum crystal. 1907-De Forest adds the. grid to Fleming valves. 1915-First trans-Atlantic speech by wireless. 1920-Broadcasting.