Charles
Thomson Rees Wilson
Scotland
and Manchester
On
14th February 1869, Charles Thomson Rees Wilson was
born in Glencourse near Edinburgh. He came from a family
of Scottish farmers, but when he was four his father
died and the family moved to Manchester.
Wilson
was educated at Greenheyes Collegiate School in Manchester,
where no science was taught. At age 15 he went to Owen's
College, which later became the University of Manchester.
He registered as a medical student, but began by studying
science subjects, and graduated first class when he
was eighteen. He spent one more year in Manchester before
being applying to Cambridge. In 1888 won a scholarship
to Sidney Sussex College.
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Student
at Cambridge
It
was at Cambridge that Wilson became keenly interested
in the physical sciences. He took his degree in 1892
and was the only graduating physicist that year. He
began working as a demonstrator and private tutor of
physics, and spent a short time as science master for
Bedford Grammar School. When the Cavendish began teaching
physics to medical students Wilson returned to Cambridge
as a supervisor of practical work.
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The
Cloud Chamber
Wilson
is most famous for his cloud
chamber, a piece of apparatus described by Ernest
Rutherford as "the most original and wonderful
instrument in scientific history". The cloud chamber
allows the tracks of ionising particles to be seen,
and was the primary detector of particles in nuclear
physics for over forty years. The inspiration for the
cloud chamber came in September 1894, when Wilson was
working as a temporary meteorological observer at the
top of Ben Nevis. He reported that "the wonderful
optical phenomena shown when the sun shone on the clouds
surrounding the hill-top, and especially the coloured
rings surrounding the sun (coronas) or surrounding the
shadow cast by the hill-top or observer on mist or cloud
(glories), greatly excited my interest and made me wish
to imitate them in the laboratory."
Wilson
produced clouds in the laboratory by expanding moist
air, a method devised by the Scottish engineer John
Aitken in 1880. Aitken had found that air needed to
contain dust for clouds to form, but when Wilson repeated
the experiments he found that large expansions would
repeatedly produce clouds, even in dust-free air. He
published his results in 1895, and soon showed that
the clouds were forming on charged particles in the
air. Wilson continued to improve on the designs of cloud
chambers until 1935, and left his original Cloud Chamber
to the Museum at
the Cavendish Laboratory.
In
1896 Wilson was appointed as Clerk Maxwell Student at
Cambridge, which gave him three years to devote entirely
to research. He then continued his research for a year
at the Meteorological Council, demonstrating the atmospheric
electricity that was due to the ions he had detected
in air.
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Fellow
and Professor
In
1900 Wilson was elected as a Fellow of the Royal Society,
a Fellow of Sidney Sussex College and appointed as a
University Lecturer and Demonstrator on a combined salary
of £150 a year. He continued his experiments,
hoping that the track of ionising particles could be
made visible and photographed when they caused condensation
in the cloud chamber. In 1911 he completed his apparatus
and was able to see the paths of individual alpha- and
beta-particles and electrons.
Wilson's
account of his discovery was presented to the Royal
Society the following year. His discoveries were incredibly
important to science, making visible phenomena which
had previously only been deduced from measurements of
the particle's electrical properties.
After
the First World War, Wilson moved from the Cavendish
to the Solar Physics Observatory in West Cambridge.
He continued his work with the cloud chamber, taking
hundreds of photographs of the tracks of X-rays, alpha
and beta particles. Many of Wilson's original photographs
are still featured in physics books today.
Wilson
was in charge of the Third Year experimental class in
the Cavendish for several years, and known for setting
projects to his class which were more engaging and rewarding
than the stereotyped experiments offered in other teaching
laboratories at the time. Wilson also lectured in the
Cavendish, as Sir Lawrence
Bragg later described: "the manner of delivery
was not perhaps ideal; the blackboard heard more sometimes
than we did. But his way of loooking at a problem was
fascinating, and I confess I've used the notes of his
lectures for my own ever since."
Besides
the cloud chamber and condensation nuclei, Wilson did
research into the conductivity of air, atmospheric electricity
and thunderstorms. In 1925 he was appointed as Jacksonian
Professor of Natural Philosophy, which he remained until
his retirement in 1934.
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Retirement
In
1936 Wilson returned to Scotland where he continued
to do research into thunderstorms at Edinburgh. In 1955,
on learning the meteorological students at the university
were being taken on flights by the Royal Air Force,
Wilson was 'taken off the ground for the first time
in 86 years', and given the opportunity to see and feel
the insides of the thunderclouds which he had been studying
all his life.
Throughout
his life Wilson won many awards, including the Hughes
Medal (1911), Royal Medal (1922) and Copley Medal (1935)
from the Royal Society, and the Nobel Prize for Physics,
shared with A.H. Compton, in 1927. In 1908 he married
Jessie Fraser Dick, and together they had a son and
two daughters.
Wilson
died on 15th November 1959 after a brief illness. His
biographer Blackett described him as gentle and serene,
indifferent to prestige and honour, a man whose work
had come from an intense love of the natural world,
and a delight in its beauties.
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