Image: Post Office Engineers

Description: British Post Office engineers inspect Guglielmo Marconi's wireless telegraphy (radio) equipment, during a demonstration on Flat Holm island, 13 May 1897. This was the world's first demonstration of the transmission of radio signals over open sea, between Lavernock Point and Flat Holm Island, a distance of 3 miles. In the background is the spark-gap transmitter, an induction coil (right) that generates high voltage pulses that create sparks between the balls of the Righi spark gap (left), which excites oscillating currents in a wire antenna suspended aloft by the pole seen in the center, ratiating radio waves. Information is transmitted by switching the transmitter on and off rapidly using a switch called a telegraph key (not visible), spelling out text messages in Morse code.
Title: Post Office Engineers
Credit: Cardiff Council Flat Holm Project
Author: Cardiff Council Flat Holm Project
Permission:   This work is free and may be used by anyone for any purpose. If you wish to use this content, you do not need to request permission as long as you follow any licensing requirements mentioned on this page. Wikimedia has received an e-mail confirming that the copyright holder has approved publication under the terms mentioned on this page. This correspondence has been reviewed by an OTRS member and stored in our permission archive. The correspondence is available to trusted volunteers here. If you have questions about the archived correspondence, please use the OTRS noticeboard. Ticket link: https://secure.wikimedia.org/otrs/index.pl?Action=AgentTicketZoom&TicketID=1608324
Usage Terms: Creative Commons Attribution 3.0
License: CC BY 3.0
License Link: http://creativecommons.org/licenses/by/3.0
Attribution Required?: Yes