Wireless Telegraphy
Nikola Tesla and other scientists and inventors showed the usefulness of wireless telegraphy, radiotelegraphy, or radio, beginning in the 1890s. Alexander Stepanovich Popov demonstrated to the public his wireless radio receiver, which was also used as a lightning detector, on May 7, 1895. He proudly demonstrated his wireless receiver before a group of reporters on a stormy August evening in 1895. It was attached to a long 30-foot pole that he held aloft to maximize the signal. When asked by one of the reporters if it was a good idea to hold this metal rod in the middle of a storm he replied that all was well. After being struck (and nearly killed) by a bolt of lightning he proudly announced to the world that his invention also served as a "lightning detector".
Albert Turpain sent and received his first radio signal, using Morse code, in France, up to 25 meters in 1895.
Guglielmo Marconi sent and received his first radio signal in Italy up to 6 kilometres in 1896. On 13 May 1897, Marconi, assisted by George Kemp, a Cardiff Post Office engineer, transmitted the first wireless signals over water to Lavernock (near Penarth in Wales) from Flat Holm. Having failed to interest the Italian government, the 22-year-old inventor brought his telegraphy system to Britain and met William Preece, a Welshman, who was a major figure in the field and Chief Engineer of the General Post Office. A pair of masts about 34 metres (112 ft) high were erected, at Lavernock Point and on Flat Holm. The receiving mast at Lavernock Point was a 30-metre (98 ft) high pole topped with a cylindrical cap of zinc connected to a detector with insulated copper wire. At Flat Holm the sending equipment included a Ruhmkorff coil with an eight-cell battery. The first trial on 11 and 12 May failed but on the 13th the mast at Lavernock was extended to 50 metres (164 ft) and the signals, in Morse code, were received clearly. The message sent was "ARE YOU READY"; the Morse slip signed by Marconi and Kemp is now in the National Museum of Wales.
In 1898 Popov accomplished successful experiments of wireless communication between a naval base and a battleship.
In 1900 the crew of the Russian coast defense ship General-Admiral Graf Apraksin as well as stranded Finnish fishermen were saved in the Gulf of Finland because of exchange of distress telegrams between two radiostations, located at Hogland island and inside a Russian naval base in Kotka. Both stations of wireless telegraphy were built under Popov's instructions.
In 1901, Marconi radiotelegraphed the letter "S" across the Atlantic Ocean from his station in Poldhu, Cornwall to St. John's, Newfoundland.
Radiotelegraphy proved effective for rescue work in sea disasters by enabling effective communication between ships and from ship to shore.
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