The Librarian Who Measured the Earth

This is one of my favorite books when it comes to have a story hour with children 8-12 years old (and not 4-8, even though younger children can still be fascinated by the story, the logic here and kind of information requires more maturity!).
This nice biography for children just shows that all this knowledge we have is a heritage of those past great minds. This book talks about a curious and intelligent child who becomes the "librarian who measured the earth". It shows how a library can be the perfect place for curious people to gather information and think and how inter-disciplinary thinking and learning is important. There is science, maths, geography, and much more: the imagination and logic of this great man: Erastothenes.

This book contains a cursory biograph of his life and a good discussion of the measurement technique used by Eratosthenes. The story was captivating for my 6 year-old son.
Through the text and wonderful pictures, the book shows the scientific method used by Eratosthenes to measure the circumference of the earth. The book is a little heavy on theory (lost on a young child). As a science teacher, I would have used this in my earth science classroom to spark discussion with students.

I'd just like to repeat what the other middle school reviewers are saying about this book--namely that it works with kids. Beautifully illustrated, concise, great for a multi-disciplinary lesson. It covers history in an engaging way and makes students think. I wish publishers would get more books to us history teachers like this one. Teachers who liked this might want to check out Joy Hakim's new science "textbook" which covers early science and math. Every time I look at it I like it more.

"The Librarian Who Measured the Earth" by Kathryn Lasky

This book is one of my most treasured possessions. It is a children's book, but it does contain the mathematics and geometry by which Eratosthenes measured the circumference of the earth to within 2% of the accurate measurement accepted by modern scientists. Eratosthenes did this in the 3rd Century B.C.E. when he was the head librarian in Alexandria, Egypt, ruled by the Ptolemaic kings. [The Ptolemaic Kings were the Hellenic successors to Alexander the Great's empire, after his death].

The book is in a large format, and the color illustrations are lovely, and they enhance the text. The author, Kathryn Lasky has done an excellent job of assimilating vast amounts of technical and historical data and reducing it to form that is appreciated by those without deep grasp of geometry and mathematics. I've looked into some of the geometry which Eratosthenes drew upon to make his determinations and it can be very technical.

It may be that some learned people were well acquainted with the proof of Eratosthenes and that this knowledge was possessed by Christopher Columubs, even as he was pleading with monarchs Ferdinand and Isabella of Spain, during the very period when their courtiers were developing "Mad Queen Chess" which is the game we play today.

One of the fun things to do, particularly to enhance the learning experience, is to copy the data from this book and enlarge upon it. That Eratosthenes was able to do this fascinates me to no end.