. His own photograph of the equipment he had set up can be
seen in the Deutsches Museum in Munich.

To detect the electromagnetic waves Hertz employed a simple form
of oscillator, which he termed a resonator. But it was not sensitive
enough to detect waves at any great distance. Before wireless
telegraphy could become practicable, a more delicate detector was
necessary.

Credit is due to Edouard Branly (1844-1940) of France for
producing the first practical instrument for detecting Hertzian waves,
the coherer. It consisted of two metal cylinders with leads attached,
fitted tightly into the interior of a glass tube containing iron or
steel filings. The instant an electric discharge of any sort occurred
the coherer became conductive, and if it was tapped lightly its
conducting property was immediately destroyed. In practice the
tapping was done automatically by a tapper which came into action the
moment the coherer became conductive.

In Russia the physicist Aleksandr Popov (1859-1905) had used a
coherer while engaged in the investigation of the effects of lightning
discharges. He suggested that such discharges could possibly be used
for signaling over long distances. Old timers may remember that
about 50 years ago Russian amateurs used to send out a QSL card with a
drawing of Popov and a caption which claimed that he was 'the inventor
of radio'.

In Italy, a young 22-year-old electrician became interested in
electromagnetic radiation after reading papers by Professor Augusto
Righi (1850-1921). It was Guglielmo Marconi (1874-1937), the son of a
well-to-do landowner who lived in Bologna, and who was married to
Annie Jameson of the well known Irish Whiskey family. Guglielmo, their
second son, had his early education at a private school in Bedford,
England, and later at Livorno and Florence in Italy. When he read
about the experiments of Heinrich Hertz and about Popov's suggestion,
he saw the possibility of using these waves as a means of signaling.
His first transmitter, shown in the accompanying photograph, did not
radiate very far. When he folded the metal plate into a cylinder and
placed it on a pole 30 feet above the induction coil and connected to
it by a vertical wire, he was able to detect the radiation nearly two
kilometres away. Marconi realised that his signaling system would be
most useful to shipping, and in those days England possessed the
world's greatest navy and the world's bi