the dawn of amateur radio in the u[1].k.(收音机雏形的诞生)-第1章
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The dawn of amateur radio in the U。K。 and Greece ： a personal view
The dawn of amateur
radio in the U。K。
Norman F。 Joly。
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The dawn of amateur radio in the U。K。 and Greece ： a personal view
Prologue
Thales of Miletus。
Thales； who was born in 640 B。C。； was a man of exceptional wisdom
and one of the Seven Sages of Ancient Greece。 He was the father of Greek；
and consequently of European philosophy and science。 His speculations
embraced a wide range of subjects relating to political as well as to
celestial matters。 One must remember that even up to the 18th century
there was no clear distinction between philosophy and science； both being
products of the human mind in its attempts to explain reality。
Thales had studied astronomy in Egypt so he was able to draw up
accurate tables forecasting when the River Nile would be in flood。 But he
first became widely known by anticipating an eclipse of the sun for May
585 B。C。； which happened to coincide with the final battle of the war
between the Lydians and the Persians。 He had used some tables drawn up
by Babylonian astronomers； but he did not succeed in forecasting the exact
day （May 28th） or the hour of the spectacular event。
It can well be said that Thales was the first man ever recorded to have
cornered the market in a commodity： having foreseen a three…year drought
he bought up large quantities of olive oil and stored it for sale at a later
date。
But who could possibly have imagined that one of Thales' original
speculations would affect the Radio Amateurs of the 20th Century？ He
believed that certain inanimate substances； like lodestones （magnetic rocks）
and the resin amber； possessed psyche （a soul）。
Many centuries had to elapse before this soul was identified as static
electricity and magnetism and harnessed for the generation of mains
electricity which dramatically altered the pattern of life on our planet … and
also led to the creation of our hobby of Amateur Radio。
About 400 years ago an English scientist called William Gilbert
（1544…1603）； who had read about the unexplained observation of Thales；
also became interested in the intangible property and decided to call it
electricity； from the classical Greek word for amber； which is electron。
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The dawn of amateur radio in the U。K。 and Greece ： a personal view
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The dawn of amateur radio in the U。K。 and Greece ： a personal view
CHAPTER ONE
THE DEVELOPMENT OF ELECTRICITY
The phenomenon which Thales had observed and recorded five
centuries before the birth of Christ aroused the interest of many scientists
through the ages。 They made various practical experiments in their efforts
to identify the elusive force which Thales had likened to a 'soul' and which
we now know to have been static electricity。
Of all forms of energy； electricity is the most baffling and difficult to
describe。 An electric current cannot be seen。 In fact it does not exist
outside the wires and other conductors which carry it。 A live wire carrying
a current looks exactly the same and weighs exactly the same as it does
when it is not carrying a current。 An electric current is simply a movement
or flow of electrons。
Benjamin Franklin； the American statesman and scientist born in
Boston in 1706； investigated the nature of thunder and lightning by flying
a child's kite during a thunderstorm。 He had attached a metal spike to the
kite； and at the other end of the string to which the kite was tied he secured
a key。 As the rain soaked into the string； electricity flowed freely down the
string and Franklin was able to draw large sparks from the key。 Of course
this could have been very dangerous； but he had foreseen it and had
supported the string through an insulator。 He observed that this electricity
had the same properties as the static electricity produced by friction。
But long before Franklin many other scientists had carried out
research into the nature of electricity。
In England William Gilbert （1544…1603） had noticed that the powers
of attraction and repulsion of two non…metallic rods which he had rubbed
briskly were similar to those of lodestone and amber … they had acquired
the curious quality we call magnetism。 Remembering Thales of old he
coined the word 'electricity'。
Otto von Guericke （1602…1686） a Mayor of Magdeburg in Germany；
was an amateur scientist who had constructed all manner of gadgets。 One
of them was a machine consisting of two glass discs revolving in opposite
directions which produced high voltage charges through friction。 Ramsden
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The dawn of amateur radio in the U。K。 and Greece ： a personal view
and Wimshurst built improved versions of the machine。
A significant breakthrough occurred when Alessandro Volta （1745…
1827） in Italy constructed a simple electric cell （in 1799） which produced
a flow of electrons by chemical means。 Two plates； one of copper and the
other of zinc； were placed in an acid solution and a current flowed through
an external wire connecting the two plates。 Later he connected cells in
series （voltaic pile） which consisted of alternate layers of zinc and copper
discs separated by flannel discs soaked in brine or acid which produced a
higher electric pressure （voltage）。 But Volta never found the right
explanation of why his cell was working。 He thought the flow of electric
current was due to the contact between the two metals； whereas in fact it
results from the chemical action of the electrolyte on the zinc plate。
However； his discovery proved to be of incalculable value in research； as
it enabled scientists to carry out experiments which led to the discoveries
of the heating； lighting； chemical and magnetic effects of electricity。
One of the many scientists and physicists who took advantage of the
'current electricity' made possible by Volta's cells was Hans Christian
Oersted （1777…1851） of Denmark。 Like many others he was looking for a
connection between the age…old study of magnetism and electricity； but
now he was able to pass electric currents through wires and place magnets
in various positions near the wires。 His epoch…making discovery which
established for the first time the relationship between magnetism and
electricity was in fact an accident。
While lecturing to students he showed them that the current flowing
in a wire held over a magnetic compass needle and at right angles to it
（that is east…west） had no effect on the needle。 Oersted suggested to his
assistant that he might try holding the wire parallel to the length of the
needle （north…south） and hey presto； the needle was deflected！ He had
stumbled upon the electromagnetic effect in the first recorded instance of a
wire behaving like a magnet when a current is passe
