10 A: I was able to accurately measure the circumference of the earth.. Ptolemy III an ancient Egyptian ruler papyrus type of paper invented in ancient Egypt scrolls pieces of paper ro
Trang 11 Q: Where were you born?
2 A: I was born in Cyrene, Greece (which is present-day Libya),
in 276 BC Both of my parents were Greek
3 Q: Did you have any nicknames growing up?
4 A: I did have one; my friends called me Beta, which is the
second letter of the Greek alphabet They teased me, saying I fell just short of first place (which was occupied
by Archimedes) Later in my life, I received the nickname
Pentathlos It’s funny, because literally this word refers
to an athlete who participated in five sporting events, but eventually was used to describe someone who was well rounded, or good at several different things
5 Q: What was your childhood like?
6 A: My parents told me that I had always been a curious baby, sticking my hands into new and foreign objects, typical
baby behavior But as I grew older, I asked thousands of
questions that nobody could answer I was fascinated by
the sky, because it was something that I could not reach and touch I wondered how far away the sun was, what
it was made of, where the winds came from, and how the stars moved When I was about six years old, I began to
go to the gymnasium, which is a school I learned reading, writing, arithmetic, music, and poetry I was very strong in math, but geography was by far my favorite subject
nicknames informal names that are different from people’s actual names Archimedes an ancient Greek mathematician and scholar
foreign unknown
Eratosthenes
Ask Questions What
other information do
you want to know
about Eratosthenes’
nicknames? Ask him a
question about them
How do you think
Eratosthenes would
answer?
Reading
Strategy
Content
Mathematics
Reading 2
The world as known
to Eratosthenes,
200 BC
Trang 27 Q: What were the turning points of your life?
8 A: Well, I sailed to Athens to study there Somehow I made
myself so known in several fields that Ptolemy III of Egypt
invited me to Alexandria There I tutored his son Philopater
and became the librarian for the great Alexandrian
University That completely changed my life It was the most
exciting place to be, because it was considered the center
of all learning The library and museum were the best in
the world In the library at Alexandria, there were 700,000
papyrus scrolls and 40 librarians.
9 Q: What were your major accomplishments?
10 A: I was able to accurately measure the circumference of
the earth And I, being the list maker that I am, worked on
figuring out the dates of literary and political events, a list
called a chronology I wrote some books as well—one on
comedy, one on history, and one on the constellations.
Ptolemy III an ancient Egyptian ruler
papyrus type of paper invented in ancient Egypt
scrolls pieces of paper rolled into a circular shape
circumference distance around something circular
chronology list of events in the order they happen
constellations groupings of stars that look like objects
Ask Questions Think
of another question
to ask Eratosthenes about his work as a librarian Do research
to see if you can find the answer to your question
Reading Strategy
Reading Check ✓
1 Recall details
Where did Eratosthenes grow up? What is the name of that country today?
2 Make inferences
Why was Eratosthenes given the nickname Pentathlos?
3 Draw conclusions
Did Eratosthenes enjoy being a librarian? Explain
Library of Alexandria, 300 BC
Trang 311 Q: How did you measure the circumference of the earth?
12 A: Well in order to find a circumference, I made two assumptions: that the earth was round and that the sun’s rays were essentially parallel because the sun was so
far away I imagined that a section of the earth ran from Alexandria to Syene, and if I could figure out the distance, and measure the inside of the section they created, I would
be able to calculate the earth’s circumference I picked Syene because I heard from a caravan passing through Alexandria that on the twenty-first day of June at precisely
midday, the sun would shine directly down a certain well in
Syene, lighting up the well but casting no shadows on its
walls I supposed the earth was like a giant grapefruit; if I could find the distance of one section of the arc, I could find out how many of these same-size sections it would take to make up the whole grapefruit Since a circle is made up of
360 degrees, with the inside angle I could figure out how many inside angles make up 360,
and then the whole circumference
13 The circumference of the earth calculated by Eratosthenes was only
200 miles off from the modern-day
figure, and considering the magnitude
of the numbers, it can be considered
the first accurate measurement After
his discovery, he provided the first mathematically based map of the world His Geographica, geography book of the world,
was finally complete
assumptions beliefs that something is true essentially just about
calculate figure out using math caravan group of people making a trip together precisely exactly
casting throwing magnitude great size
Ask Questions
Eratosthenes tells
how he calculated
the circumference of
the earth Ask three
questions about the
method he used
Reading
Strategy
Cairo Memphis
Antinoopolis
Nile River
Ptolemais
Syene
Heliopolis
Alexandria
Eratosthenes made his calculations based on the distance between Alexandria and Syene.