Page 28 - BBC History The Story of Science & Technology - 2017 UK

Ideas & Inventions / Objects

7 CROOKES’ TUBE
The mysterious glowing
apparatus in which
electrons were discovered

It’s the 1870s. Imagine the bewilderment
of scientists gazing at this glowing electric
tube. Inside, it contains only gas at a very
low pressure, so what could be producing
that eerie green luminosity? The strong
shadow of a Maltese cross suggests that
this is an optical phenomenon, but
another experiment shows that something
– but what? – is strong enough to push
a little cart along some miniature rails.
Could it be a stream of particles, or
perhaps some mysterious rays?
This apparatus was developed by
William Crookes (1832–1919), an ingenious
British physicist who created movement
and shadows to back up his claims that
a strange substance is being emitted by
one of the electric plates in his tube.
Crookes suggested that spiritualism may
be behind the effect, and after several
prominent mediums survived his rigorous
tests without being caught cheating, some
eminent scientists believed that it really
was possible to contact the dead.
Sceptics accused them of being duped
by charlatans, but Crookes suggested
that radio might have a human analogy,
so that people with especially sensitive
organs can tune in to vibrations carried
through space. Crookes’s evidence was
persuasive, and he was partially vindi-
Alessandro Volta’s drawing of the world’s first electric battery (1800) cated when his rays were shown to be
electrons. His séance experiences have
never been fully explained.
6 VOLTA’S PILE Crookes’ tube led some
The prototype battery that its inventor scientists to believe that it’s
perfected by giving himself electric shocks possible to contact the dead

Alessandro Volta (1745–1827) was frogs’ legs – was identical to artificial
a sharp operator. Based in Italy, he electricity produced in a laboratory.
consolidated his international Volta was as interested in
reputation by cultivating scientific defeating his rivals – especially his
friendships all over Europe and fellow Italian Luigi Galvani – as in
pledging his allegiance to Napoleon. providing solid evidence. His article
In 1800, he chose British journals for was a rhetorical masterpiece,
launching his revolutionary instru- convincing his readers by describing
ment that provided a new source of his results at length yet managing to
power – current electricity. avoid the awkward questions.
To make this prototype battery,
Volta piled up discs on vertical glass
rods, alternating two different metals
and separating them with cardboard Volta was as
soaked in salty water. Incorporating
himself as an experimental subject, interested in
Volta placed one hand in the basin of
water at the bottom, and the other on defeating his
the metal plate at the top. Sometimes
he even used his tongue as a rivals as in ALAMY/SCIENCE PHOTO LIBRARY
detector. The shocks he received
were, he claimed, proof that animal providing solid
electricity – the kind already
observed in electric eels or twitching evidence

28 The Story of Science & Technology