Marconi's first wireless signal (1893) : three dots that made history

In June 1896 a 22-year-old Italian physicist called Guglielmo Marconi, who had settled in London the previous year, called upon the Engineer-in-Chief of the Post Office to demonstrate his new system of 'telegraphy without wires'. He had already approached the Italian government - but it showed no interest.
The Post Office was more receptive and allowed Marconi to set up his transmitter on the roof of the Central Telegraph Office, and a receiver on the roof of a building called 'GPO South' in Carter Lane, 300 yards away.
On July 27 Marconi succeeded in sending the signals between the two locations. It was the world's first recorded wireless message. The following month The Post Office gave Marconi backing to experiment with wireless apparatus on Salisbury Plain and in coastal locations.