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Telegraph Transmissions, Lavernock Point
Lavernock Point, Penarth, Vale of Glamorgan, Wales, UK
Telegraph Transmissions, Lavernock Point
associated engineer
William Henry Preece
Guglielmo Marconi
date  1892, May 1897
era  Victorian  |  category  Telecommmunications  |  reference  ST186681
photo  Jane Joyce
Making telecommunications history in 1897, Guglielmo Marconi transmitted the first radio signal across open sea between Lavernock Point in the Vale of Glamorgan, south Wales, and Flat Holm Island in the Bristol Channel. A few days later he sent radio signals from Lavernock Point to the Somerset coast, then a record distance. William Henry Preece had used the same spot to experiment in 1892.
Italian inventor Guglielmo Marconi (1874-1937) was an electrical engineer and pioneer of radio. He realised that reliable long-range wireless communications had commercial and military value, and applied himself to developing such a system, based on electrical waves known as Hertzian waves, named after physicist Heinrich Hertz (1857-1894).
In 1896, aged 21, Marconi moved to Britain. A letter of introduction from electrical engineer Alan Archibald Campbell Swinton (1863-1930) led to a meeting with William Henry Preece (1834-1913). Preece was the Post Office’s engineer-in-chief, and had harnessed the power of electromagnetic inductance to transmit wireless Morse code telegraph signals across bodies of water — Coniston Water in Cumbria (1889), the Bristol Channel from here at Lavernock Point (1892), and Kilbrannan Sound in south west Scotland (1894).
Preece allowed Marconi to use Post Office facilities in London for his experiments, and he began transmitting messages from the roof of the building he was using to other government buildings.
On 2nd June 1896, Marconi applied for a British patent for Improvements in Transmitting Electrical Impulses and Signals, and in Apparatus Thereof, in which he stated: "I believe that I am the first to discover and use any practical means for effective telegraphic transmission and intelligible reception of signals produced by artificially-formed Hertz oscillations".
In early 1897, he sent Morse code radio signals across Salisbury Plain in Wiltshire. In doing so, he proved that overland wireless communications were viable. The next step was radio transmission over sea.
Lavernock Point on the south Wales coast was selected as the test location, with transmission to Flat Holm Island 5.3km to the south east in the Bristol Channel — the same route that Preece had used for his telegraphy five years previously. Marconi's trusted assistant George Stephen Kemp (1857-1933), a Cardiff Post Office engineer, kept a diary of events.
A pole was erected at Lavernock, 27.4m tall and topped by a cylindrical cap of zinc 1.8m long and 910mm in diameter. An insulated copper wire connected the cap to the detector, from which a wire was trailed down the cliff into the sea. The equipment had a spark gap transmitter, which produced a spark over 500mm long.
On Flat Holm, apparatus was erected to verify both Marconi's and Preece's experiments, enabling a direct comparison. Marconi remained at Lavernock Point, at a cliff top site some 18m above sea level, while Kemp and his nephew Herbert went to the island.
Preece's apparatus on Flat Holm was tested and on 10th and 11th May 1897, Marconi’s team repeated the original electromagnetic transmission experiments.
Initially, Marconi's radio telegraphs equipment did not record intelligible signals. However, by moving the Lavernock apparatus to the foot of the cliff, connecting it to the pole above with an additional 18.3m of wire, the aerial length was increased to 45.7m. This simple modification made all the difference.
Testing was conducted over several days, with the trials on 13th and 14th May observed by Preece and other officials. On 13th May 1897, Marconi transmitted the first radio message in Morse code — "CAN YOU HEAR ME". Shortly afterwards, Kemp transmitted a reply — "YES LOUD AND CLEAR". The original message recording slip is now in the National Museum of Wales.
The success of the tests encouraged Marconi to try transmitting over a greater distance. His Flat Holm equipment was relocated to Brean Down Fort (ST280592) near Weston Super Mare on the Somerset coast, 14km from Lavernock Point. The aerial consisted of a kite wire attached to a mast approximately 100m tall. On 18th May, successful radio transmissions were made over a then record distance.
In June 1897, Preece concluded a lecture to the Royal Institution by remarking, "… Marconi has produced, from known means, a new electric eye more delicate than any known electrical instrument and a new system of telegraphy which will reach places hitherto inaccessible".
On 2nd July 1987, Marconi's British patent (No.12039) was granted and he applied for an American one (No.674846, received 21st May 1901).
On 20th July, he founded the Wireless Telegraph & Signal Company Ltd (renamed Marconi's Wireless Telegraph Co. Ltd in 1900), with Kemp as head of engineering development. Their involvement with the Post Office ended — as a public servant, Preece could not involve the government-run Post Office in a commercial venture — and the patent rights for Marconi’s radio discoveries were vested in the new company.
Marconi went on to establish the first radio link across the Atlantic Ocean (1901), and shared the 1909 Nobel Prize for Physics with Karl Ferdinand Braun (1850-1918) for "contributions to the development of wireless telegraphy".
In 1948, a bronze plaque commemorating Marconi and Kemp’s achievements was unveiled in the churchyard of St Lawrence in Lavernock. It reads, "NEAR THIS SPOT THE FIRST RADIO MESSAGES WERE EXCHANGED ACROSS WATER BY GUGLIELMO MARCONI AND GEORGE KEMP BETWEEN LAVERNOCK & FLAT HOLM 11th MAY, LAVERNOCK & BREAN DOWN 18th MAY 1897".
Lavernock Point is now a nature reserve, managed by the Wildlife Trust of South and West Wales. It is tempting to imagine the small masonry tower that stands on the cliff not far from the church as the location for Marconi's transmitting equipment. However, we have not discovered any evidence that it was used by either Preece or Marconi.
Research: ECPK
"Voices from the Ether: The History of Radio" by Gordon Bathgate, Girdleness Publishing, Aberdeen, 2012
"The Worldwide History of Telecommunications" by Anton A. Huurdeman, John Wiley & Sons, Hoboken, New Jersey, 2003
"The Science of Radio" by Paul J. Nahin, Springer Science & Business Media, 2001
"The Early British Radio Industry" by Rowland F. Pocock, Manchester University Press, 1988

Telegraph Transmissions, Lavernock Point