>>Thank you for joining me in the History
of Science Collections of the University of
Oklahoma Libraries. Let's look at a few treasures
from the vault that throw light on the story
of Stonehenge.
On this geological map of England and Wales,
prepared by William Smith in 1815, Stonehenge
seems to rise up out from the earth on the
Salisbury Plain - right between the "A" and
"I" in the word "plain". Stonehenge lies less
than 10 miles due north of Salisbury.
To enter the world of the people who made
Stonehenge, we need to get away from our streetlights,
look up at the stars, and make ourselves at
home in the starry heavens. Here is Cygnus
the Swan flying above the river of the Milky
Way. This atlas by Johann Bode, printed in
1801, represents a high level fusion of artistic
beauty and science. Bode plotted more than
17 thousand stars and 25 hundred nebula among
the figures of the constellations. Few atlases
are larger or more beautiful. After Bode's
monumental effort, scientific star atlases
became more specialized or dispensed all together
with the artistic depiction of constellation
figures. Until recently, evening hours, day
after day, were filled with the beauty of
the nighttime sky. But most of us today would
find one night spent under truly dark skies
an unforgettable experience.
On this page, we can see the constellations
of Gemini, Orion, and Taurus - Orion the Hunter,
and Taurus the Bull, Gemini the Twins. These
are three of the most prominent constellations
of the winter hexagon. Many constellations,
including these three, are of Babylonian origin.
88 constellations are officially recognized
today.
Here is the constellation of Orion the Hunter.
This beautiful work was written as an introduction
to the nighttime sky as a delightful dialogue
between a mother and her daughter. Another
plate shows a striking depiction of the full
moon against the backdrop of a completely
dark sky. And my favorite is at the very front,
a foldout plate that shows the constellations
of Corvus, Crater and Hydra. Whitwell's 400-page
book includes 23 engraved plates, four of
them hand-colored.
Flashcards are a great way to become acquainted
with the constellations. This set, titled
Urania's Mirror, was published in 1823 by
Jehoshaphat Aspin. Holes in the cards for
the stars, allow you to look through the card
at a light and see the constellation pattern
appear. Here's the card for the big dipper,
the big bear - Ursa Major. We can see the
big dipper inside the hindquarters of the
bear. Four stars make the bowl and three stars
make the handle. Only the most imaginative
can see a bear surrounding the big dipper.
His nose is located far off to the side. The
handles of the big and little dippers represent
the tails of the big and little bears on ancient
star maps even though modern bears don't have
tails. The big bear was regarded as a bear
before Homer, and an ancient Greek story explains
why the big and little bears have their tails
stretched out. Many star patterns look like
dippers, triangles or squares in the sky.
There are very few that actually resemble
bears or people. Yet constellations were named
to honor particular characters in ancient
stories, not because the star pattern actually
looked like the character being honored. It
took imagination to invent the constellation
figures a long time ago, and it takes imagination
to learn them now.
This is Sagittarius the Archer, a centaur,
another constellation dating to Babylonian
times. If we track the motion of the sun around
the constellations over the course of a year,
we'll find that the sun follows the same path
year after year, over and over again. The
sun's path is called the ecliptic, and any
constellation that includes the ecliptic is
called a zodiac constellation. Zodiac means
circle of animals, since all but one of the
zodiac constellations are named after living
beings, either animal or human or some kind
of hybrid. The planets never stray far from
the ecliptic. So an unexpected bright star
in any zodiac constellation might be a planet
wandering through on its journey around the
sky.
The entire sky can be represented by the ecliptic
and the equator on an armillary sphere, like
this one. With an armillary sphere, we can
track the apparent motions of the sun, moon,
and planets along the ecliptic. The great
circle of the ecliptic shown here in brass
lies at an angle of 23 and a half degrees
from the circle of the celestial equator.
This fact was reported by Plato in his dialogue
the Timaeus.
This 18th century book by Benjamin Martin
explains how to use the armillary sphere.
Other fundamental, astronomical instruments
include a celestial globe, a terrestrial globe
(because the geography of the earth and the
cartography of the skies coincides), and an
orrery, which is a piece of clockwork to model
the motions of planets. Martin operated an
instrument shop in London, and he wrote more
than 60 different catalogs and manuals to
promote popular understanding of astronomy
and interest in scientific instruments.
Have you noticed the days growing shorter
in the fall and longer in the spring? Have
you noticed how the sun rises at different
locations on the eastern horizon depending
on the time of year? At Stonehenge and other
stone circles, preliterate cultures used giant
stones or megaliths as their armillary spheres,
charting seasonal intervals by arranging sunrise
markers sided toward the eastern and western
horizons. Let's say we're facing due east
along the horizon. So, we need a horizon.
And we're watching the sun rise in Leo the
Lion. And a megalith, of Stonehenge, is right
there along the horizon. Twice a year the
sun will rise directly above this megalith.
In the early morning hours, as the sun rises,
the megalith can point to the location of
the sun. The two days each year when the sun
rises due east, it also sets due west, and
those are the equinoxes where the lengths
of the day and the night are equal. But on
the other dates through the year, the sun
does not rise due east. Rather, we see the
sun rise at points running north or south
of due east - maybe over here, or over here.
The position of the sun changes its rising
point along the eastern horizon like a pendulum
swinging back and forth through the year.
The two days each year when the sunrises reach
their extreme northerly and extreme southerly
reaches on the horizon, when the sun seems
to stand still before turning back and going
the other way, are called the solstices. So
the summer solstice and the winter solstice
can be marked on the horizon with additional
megaliths.
The changing horizon points of sunrises and
sunsets and similar patterns for the moon
are obvious astronomical phenomena that were
observed by preliterate cultures using stone
circles like Stonehenge. Perhaps preliterate
cultures knew more about the motions of the
sun and moon along the horizon than most 21st
century Americans. Some astronomers will go
further and say that Stonehenge was the first
astronomical observatory. But we need to be
cautious of such claims, which involve additional
assumptions.
In a well-known book, astronomer Gerald Hawkins
claimed that the circle of Aubrey holes were
used to predict lunar eclipses, Stonehenge
decoded. The astronomer Fred Hoyle came up
with a different method by which he could
use the same structures to predict eclipses
as well. But the exercises of Hawkins and
Hoyle are largely beside the point because
we have little evidence that the structures
were actually used by the builders of Stonehenge
in that way. Any 10 stones in a rough circle
will display a number of alignments with significant
astronomical points on the horizon simply
due to chance. Such rational reconstruction
is not history.
There is also the inherent difficulty of determining
alignments. Should one site from the left
or from the right side of the selected stones?
Or even crossover, siting from one side of
the near stone toward the opposite side of
the far stone? Should one aim for the first
gleam of sunrise? The midpoint of the solar
disc? Or the first moment when we can see
the full face of the sun?
A host of writers on Stonehenge fall prey
to rational reconstruction, or writing history
backwards. Their enthusiasm for reading present
day knowledge back into the past clouds their
historical sensibility. So rational reconstruction,
sometimes called Whig history or presentism,
all mean writing history backwards. Evaluating
the past in terms of present knowledge. Interpreting
Stonehenge as if it were a modern astronomical
observatory. Certainly there were no telescopes
at Stonehenge. And who is to say that Stonehenge
was an observatory instead of a temple? Who
is to say that it was designed for cooly rational
scientists instead of hot-blooded priests?
Who says astronomy and priestcraft were incompatible
at that time anyway?
Rational reconstruction obscures many interesting
questions. It undermines our historical sensibility
and projects modern perspectives onto the
past in a way that hinders our understanding
of the way they saw their own world. So what
do we really know of the actual people who
created Stonehenge? Not much. There are no
inscriptions, no writings, no books in which
they explained for our benefit what they were
doing and why they did it. Just a heap of
stones. This is why historians sometimes say
that history begins at Sumer in ancient Mesopotamia,
rather than with archaeology and archeoastronomy,
as valuable and as interesting as those disciplines
are. But there's another way Stonehenge entered
written historical texts, and that is the
story of how Stonehenge has been interpreted.
How have people understood Stonehenge? Throughout
most of the period covered by this course,
residents of Britain seemed satisfied with
the explanation that giants had built Stonehenge
or perhaps Merlin constructed it by his strange
magic arts. During the 16th and 17th centuries,
however, a variety of writers became interested
in the study of Britain's past and searched
for new evidence that might help them explain
Stonehenge as a part of human history.
Here is a study of Stonehenge written by Walter
Charleton, an important English atomist and
a member of the Royal Society of London. This
copy is unbound and untrimmed, stitched together
just as it was issued by the London publisher
in 1663. The title is Chorea Gigantum: or,
the most famous antiquity of Great Britain
vulgarly called Stone-Heng, standing on Salisbury-Plain,
restored to the Danes. There's a wonderful
foldout plate that is the most striking early
depiction of Stonehenge on which you can see
the massive trilithon stones, the three stones
resembling a lintel, all arranged in a circular
pattern. Charleton had background knowledge
of the history of Danish artifacts and pointed
out that the Danes had occupied southern England
in the 8th century. By comparison with Danish
monuments, Charleton argued that the Danes
built Stonehenge as a parliamentary meeting
place and a site for inaugurating kings. By
investigating the past, and recovering what
he believed to be the original purpose of
Stonehenge, Charleton thought he was restoring
his own King Charles II to an ancient throne.
So how are we to know the purpose for which
Stonehenge was built? If astronomers like
Hawkins are tempted to project their own knowledge
of astronomy back into the story of Stonehenge,
we see that Charleton's efforts were similarly
limited by the historical evidence available.
Yet once Charleton framed the question in
historical terms, the story of Stonehenge
could be pursued as a constant search for
new evidence, of any kind, interpreted in
an open-ended process. History is like that.
History is open-ended.
The lesson for us is this: to understand Stonehenge,
we will need to combine science and history.
We will need all the resources at our disposal,
and we'll need to be constantly on the lookout
for new evidence. On the one hand, our grasp
of astronomy must be equal to that of the
people who made it. But on the other hand,
to know astronomy is not enough to understand
Stonehenge. To avoid speculation and rational
reconstruction, we also need a historical
sensibility that alerts us to how people in
the past were different from us in interesting
and unexpected ways. So this book by Charleton
represents the beginning of the quest to interpret
Stonehenge with a historical perspective.
We may follow Charleton by avoiding rational
reconstruction, not only with respect to Stonehenge,
but in all of our investigations of the story
of science from Stonehenge to the age of Newton.
Science is a story. What stories do you want
to hear and tell about Stonehenge?
