xperiments on magnetism and electro- statics, discovering electrostatic repulsion and the fact that the earth acts as a giant magnet. He published his findings in 1600 in a large volume entitled De magnete written in Latin. 4 Newnes Guide to Radio and Communications Technology After this many other researchers added their own contributions to the newly developing science associated with electricity. Volta, for example, discovered that electricity could be produced by using two dissimilar metals separated by a suitable solution. Ampère made significant advances in linking electricity and magnetism by describing the magnetic forces that exist around a current carrying conductor. Georg Ohm is also well known, especially for determining how current flow was governed in a conductor. This culminated in the famous Ohm's law. Many other famous names like Faraday, Oersted and Henry made very significant contributions, laying the foundations for developments in radio that were made in the years to follow. Electricity soon started to find some uses, and became more than just a phenomenon to be demonstrated in the laboratory. The need to communicate swiftly over large distances had long been recognized. The French had set up a system of semaphore towers primarily for military purposes. However, electrical systems were soon introduced. Some early versions were very ambitious. Together Cooke and Wheatsone developed a system of pointers that indicated the required letter. In 1837 the first experimental link was opened between Euston and Camden stations. Although the experiment was a technical success the directors of the company were not impressed and the system was dismantled. Two years later the Great Western Railway Company agreed that a system could be installed between Paddington and West Drayton (not far from where Heathrow Airport stands to the west of London). Two years later this was extended to Slough, allowing communication between the stations. The initial systems required five wires, and as wire production was very