Page 51 - BBC History The Story of Science & Technology - 2017 UK

7 Overturning the 8 Explaining how

old astronomers the body works

Galileo explores the heavens William Harvey

reveals the circulation
with his telescope
Italy, 1609 of the blood
Chosen by Professor Colin Russell, The Open University England, 1628

Chosen by Dr Allan Chapman,
When Galileo became the first picture of the universe. It fitted University of Oxford
person to turn a telescope to nicely with biblical data, so for
the skies, it changed our view hundreds of years it remained the
of the universe. He discovered accepted view. However, scripture The circulation of the blood might sound like
new facts about the Sun, Moon (unless interpreted woodenly) can something we all accept but, in fact, it wasn’t
and planets, which were totally also be compatible with Coperni- discovered until 1628. Before that it was believed that
incompatible with the old theory canism. Galileo recognised this in blood came from food in your liver, then entered the
that the sky above Earth was a letter he wrote in 1615. But a heart, where it was heated before it shot out into the
unchanging and perfect. Instead scientific proof of Copernicanism veins, not the arteries. This is why Shakespeare and
they strongly supported the rival had to wait until 1838! At the trial, people like that talk about the blood “coursing
and newer heliocentric theory Galileo was found guilty and it through their veins” instead of their arteries.
of Copernicus. wasn’t until the 20th century that William Harvey was the physician to James I.
Galileo’s telescope stimulated the Vatican finally came to agree Through a meticulous study of what you might call
him to write his contentious book with him. the plumbing of the chest he came to the conclusion
Dialogue Concerning the Two that the heart didn’t heat the blood, it pumped it into
Chief World Systems (1632), the arteries. He knew from Fabricius that the veins
which more than anything else had stepladder valves in them, which Harvey realised
helped to establish Copernican- Colin Russell was helped the blood get back to the heart, completing
ism. It also led to his trial and co-author of The the circuit. Harvey was working before the micro-
impeachment before the Roman Rise of Scientific scope and didn’t know how the blood got from the
Catholic church. The old system Europe 1500–1800 arteries to the veins, but he made a very bold guess
Galileo discredited had been (Hodder, 1991). that this was done by tiny vessels so small he
almost unthinkingly adopted by He died in 2013 couldn’t see them. He was perfectly right, of course,
the church and built into their and we call them capillaries.
It was a discovery of colossal importance.
Galileo’s scientific There have been numerous advances since, but I’d
instruments, suggest that circulation was so crucial because
including his without it the others wouldn’t have emerged. You
telescope, couldn’t undertake modern surgery or give an
in Florence’s injection without circulation and can you imagine any
Galileo museum modern medical discovery without the knowledge of
the blood pumping from the heart?
Harvey’s theory was published in 1628 in a book
called On the Motion of the Heart and Blood and you
might think that he would have been inundated with
patients afterwards. Yet it almost ruined his career as
a doctor. In those days, doctors were very conserva-
tive and wouldn’t make innovations – this was
associated with quacks. Good doctors, it was
thought, dispensed medicine and diagnosed purely
in accordance with the way the ancients had taught.
So, curiously enough, the greatest medical discovery
of all time caused a considerable amount of financial
distress to its discoverer!

Allan Chapman is the author of
AKG IMAGES England’s Leonardo: Robert Hooke and the
Seventeenth-Century Scientific Revolution
(Taylor & Francis, 2004)

The Story of Science & Technology 51