kW. The frequency used is not known precisely, as Marconi did not measure wavelength or frequency, but it was between 166 and 984 kHz, probably around 500 kHz. After the experiment the original mast layout was not rebuilt, it was replaced with a four mast design, 215 feet (66 m) high and forming a 200-foot (61 m) square. Marconi later used the site for his shortwave experiments, with transmissions by Charles Samuel Franklin to Marconi on the yacht in the Cape Verde Islands in 1923 and in Beirut in 1924. The groundbreaking results of these experiments took the world by surprise and quickly resulted in his development of the Beam Wireless Service for the British General Post Office. The service opened from the Bodmin Beam Station to Canada on 25 October 1926, from the to Australia on 8 April 1927, from the to South Africa on 5 July 1927, to India on 6 September 1927 and shortly afterwards to Argentina, Brazil and the United States. The station closed in 1934 and was demolished in 1937. Six acres (24,000 m2) were given to the National Trust in 1937 with the rest of the site added in 1960. The site has a stone monument pillar, erected in November 1937 by the Marconi Company, and a number of concrete foundations and earth structures also remain. In 2001 the Marconi Centre, a new museum / meeting building, was opened close to the site by the efforts of the Poldhu Amateur Radio Club, the National Trust, and Marconi plc. The substantial building near the site, originally the Poldhu Hotel, built in 1899, is currently a care home. The visitors' book shows that Marconi stayed there in May and August 1901. Marconi also built an earlier, smaller, experimental wireless station nearby at Housel Bay – The Lizard Wireless Station. In popular culture Sherlock Holmes and Dr. Watson are staying in a cottage above Poldhu beach in "The Adventure of the Devil's Foot", a 1910 short story by Arthur Conan Doyle. In the first episode of the 2018 female-led adaptation Miss Sherlock, "Poldhu" is the name of a brand of wireless medical telemetry devices in the form of a capsule that is swallowed by the user, which the murderer exploits as triggers for liquid bombs that destroy the abdominal cavities of her victims. References Beaches of Cornwall Headlands of Cornwall National Trust properties in Cornwall History of