Lavernock

Lavernock is a hamlet in the Vale of Glamorgan in Wales, lying on the coast 7 miles (11 km) south of Cardiff between Penarth and Sully, and overlooking the Bristol Channel.

Marconi and the first radio messages across open sea

Following overland tests at Salisbury Plain during March 1897, on 13 May 1897, the Italian born and recently British based inventor, best known for his development of a radiotelegraph system, Guglielmo Marconi, assisted by George Kemp (who was a Cardiff based Post Office engineer) transmitted and received the first wireless signals over open sea between Lavernock Point and Flat Holm island.

The very first message transmitted in morse code was "ARE YOU READY". This was immediately followed by "CAN YOU HEAR ME" to which the reply was "YES LOUD AND CLEAR". The morse recording slip for the first message is on display in the National Museum of Wales.

Following the initial opening exchange there followed detailed technical messages in both directions indicating each end's equipment settings and receiving sound levels. Marconi indicated that he was using a 20-inch (510 mm) spark on his equipment.