Poldhu Wireless Station
The site is famous as the location of Poldhu Wireless Station, Guglielmo Marconi’s transmitter for the first transatlantic radio signal. In 1899, the Royal Navy had purchased three radios for its ships, and several merchant ships followed suit. It was a common belief that radio waves could not travel around the earth’s curvature, but could only travel in straight lines. Marconi was determined to disprove this.
The station’s fifty-acre (200,000 m²) plot was bought in 1900, and construction work ran from October 1900 to January 1901, designed by Marconi’s senior engineer, R N Vyvyan, whilst Professor John Ambrose Fleming designed the transmitter.
Poldhu Hotel seen in relation to the almost complete circular aerial, August 1901
The original 20-mast circular cone-shaped aerial was destroyed in a storm on 17 September 1901.
Scene of devastation, 17th September 1901. The Poldhu circular aerial after the gale.
Seven days later, on Tuesday, the 24th September 1901,
the temporary aerial is erected and used by Kemp.
For Marconi’s experiments, a temporary installation of two 160-foot (48 m) masts with a fan-shaped aerial was built. The transmitter operated with a power of roughly 13 kW and a wavelength usually estimated at 366 metres.
Across the Pond
Marconi and two assistants travelled to Newfoundland in December 1901.
Note: Marconi had previously intended to transmit from Poldhu to Cape Cod, Massachusetts, but prior to the event, both stations were damaged by storms, and Marconi relocated his North American destination to St John’s.
The SS Sardinian on which Marconi, Kemp and Paget travelled to Newfoundland
on the 26th November 1901.
Reception of the Cross-Atlantic Signal
On 12 December 1901, Guglielmo Marconi and his colleagues received an extremely short signal from Poldhu (three dots representing the code letter ‘s’) whilst listening in at Signal Hill, St John’s, Newfoundland and history was made. The full story of this event is detailed below.
Poldhu had been instructed to transmit the Morse code letter ‘S’ (dot, dot, dot) daily from 3.00 pm to 6.00 pm GMT (11.30 am to 2.30 pm, St John’s local time).
The three-dot letter ‘S’ was chosen because the switching arrangements at Poldhu on that occasion were unable to withstand the wear that a long series of dashes would have involved. Also, it ensured that the signal could be read on a Morse inker recorder through atmospherics, which tended to run all the dots and dashes into each other. Under these conditions, a series of three dots (‘S’) was more distinguishable than a series of any letter containing dashes. Similar reasoning applies to aural reception.
An attempt to raise the kite-supported aerial at Signal Hill, December
Note that the lower picture shows Marconi on the left
Fortunately, Kemp’s diary gives an account of what happened on these vital days in December:
11th: “The balloon was partly filled with hydrogen gas and I had great trouble with it. This was due to the strong wind that had suddenly sprung up at 3.00 p.m., which carried away the special mooring line, supplied by Mr Spencer, and, had it been carried away on the mooring side instead of the balloon side, I should have gone with it as its speed was like ashot out of a gun. Mr Marconi tried all the detectors from time to time, while we had the balloon under control, and called me in at intervals to try the receivers. Signals appeared at intervals on a telephone in series, when using our sensitive tube circuit, and, a times, the dots threatened to appear on the tapper.”
It is clear from this that some signals were received, but apparently, they were not definitive ones. Unfortunately, Kemp does not record any details of the circuits or coherers used, but the mention of a tapper suggests that at least one of these was a filings coherer. On the next day Kemp describes the
great triumph:
12th: “We received the three dots or the S signal repeated. We lost the first kite with 2 wires, each 510 ft. long, after it had been the means of giving us one hour for reception which was better than yesterday. Another kite was raised with one wire 500 ft. long, which appeared more in harmony with the earth’s electric medium and the signals from Poldhu Station. We were able to keep this kite up for three hours and it appeared to give good signals.”
Marconi himself was listening and described this as the crowning moment of his life. He wrote:
“Unmistakably, the three sharp little clicks corresponding to three dots, sounded several times in my ear, but I would not be satisfied without corroboration.”
“Can you hear anything, Mr Kemp?’ Isaid, handing the telephone to my assistant.”
“Kemp heard the same thing as I and I knew then that I had been absolutely right in my calculations. The electric waves which were being sent out from Poldhu had traversed the Atlantic, serenely ignoring the curvature of the earth which so many doubters considered would be afatal obstacle, and they were now affecting my receiver in Newfoundland.”
Marconi himself gave further details of what happened in his statement on the 23rd December to the Chairman and Directors of his Wireless Telegraph Company:
“…On Thursday the 12th., a successful attempt was made to rise (sic) one aerial by means of a kite, and at 12.30, 1.10, and 2.20, the pre-arranged signals from Poldhu were received in a manner which left no room to doubt their authenticity by myself and Mr. Kemp, on the telephone receiver, but not on the ordinary receiver. Signals were also received, but less distinctly, on Friday the 13th. On Saturday, the 14th., a strong gale from the northwest made it impossible to elevate either kites or balloons.”
Marconi pictured at Signal Hill, Newfoundland, just after receiving the
first wireless signal to cross the Atlantic on the 12th December 1901.
Back at Poldhu
The original mast layout was not rebuilt, but was replaced with a four-lattice wooden mast design, 215 feet (66 m) high and forming a 200-foot (61 m²) by early 1902.
Prince of Wales and Princess Mary of Teck (later King George V and Queen Mary)
visiting Poldhu on 18 July 1903.
Experiments were carried out for several years to establish a regular telegram service with Glace Bay, Nova Scotia, in Canada, but in 1906, a powerful low-frequency station was built near Clifden, Co Galway in the Connemara region in the west of Ireland to communicate with a similar one at Glace Bay.
Poldhu continued to communicate with deep-sea shipping using the callsign MPD and also transmitted a regular nightly Morse code news bulletin using the callsign ZZ. This was used by liners to print daily newspapers, whose owners paid for the copyright.
In 1910, Dr Hawley Harvey Crippen boarded the SS “Montrose” bound for Quebec with his mistress, Ethel le Neve, having murdered his wife, Cora, in London. However, Inspector Dew of Scotland Yard contacted the Captain via the new-fangled radio and, taking a faster ship, SS “Laurentic” intercepted the couple on the St Lawrence River.
The RMS Titanic
In 1912, Marconi was given a free ticket to travel on the wonderful new ocean liner RMS “Titanic” but was too busy at the time and ironically travelled on the RMS “Lusitania” (torpedoed off the Old Head of Kinsale on 7 May 1915).
RMS Titanic
Although too many lives were lost when the “Titanic” sank on 15 April 1912, those saved had the Marconi radio to thank. Communications were made between the ship and both the Marconi Station at Chatham, Massachusetts, and directly with RMS “Carpathia“, which came to pick up survivors.
Titanic Sinking
International law changed after this event. Radio watches were on hand 24 hours a day and vessels had to carry enough lifeboats for all on board.
The Poldhu Station in Later Years
The station was taken over by the Royal Navy during the First World War.
After the war, Marconi used the site for his shortwave experiments, with transmissions by Charles Samuel Franklin to Marconi on the yacht “Elettra” in the Cape Verde Islands in 1923 and near Beirut in 1924. The results of these experiments took the world by surprise and quickly resulted in the development of the Beam Wireless Service for the British General Post Office.
The service opened from the Bodmin Beam Station beaming to Canada on 25 October 1926, followed by the Tetney Beam Station to Australia, opened on 8 April 1927, the Bodmin Beam Station to South Africa on 5 July 1927, the Dorchester Beam Station to India on 6 September 1927 and shortly afterwards to Argentina, Brazil and the United States.
Poldhu continued to operate as a research station until 1933. The site was cleared in 1935, and six acres (24,000 m²) of cliff top were donated to the National Trust in 1937, with the remainder of the area added in 1960. A granite monument was erected in November 1937 by the Marconi Company, and a number of concrete foundations and earth structures also remain. On the centenary of the first transatlantic transmission, the Marconi Centre was opened close to the site by the combined efforts of the Poldhu Amateur Radio Club, National Trust and Marconi PLC.
The more substantial building near the site, originally the Poldhu Hotel, built in 1898 to house Marconi’s workers, is currently a care home.
Other Information
Please see our information on Visiting the Marconi Centre and How to Find Us.