Circumference by Nicholas Nicastro
(from the book jacket)
How do measure the size of the planet you’re standing on?
This is the story of what happened when one man asked himself that question. Nicholas Nicastro brings to life one of history’s greatest experiments – how the ancient Greek named Eratosthenes accurately determined the distance around the earth for the first time. In this fascinating narrative history, Nicastro takes a look at a deceptively simple but stunning achievement made by a single individual millennia ago, with only the simplest of materials at his disposal. How was he able to calculate the circumference of our planet at a time when the measure of distance was more a matter of a shrug and a guess? How could he be so confident in two key assumptions that underlay his calculations: that the earth was round and the sun so far away that its rays struck the ground in parallel lines? Was it luck or pure scientific genius?
Nicastro brings readers on a trip into a long-vanished world that prefigured modernity in many ways, where neither Eratosthenes’ reputation, nor the validity of his method, nor his leadership of the Great Library of Alexandria were enough to convince all his contemporaries about the dimensions of the earth. Eratosthenes’ results were debated for centuries, and only vindicated almost two thousand years after his death, during the great voyages of exploration.
This is a very readable account of the times of Eratosthenes. It is filled with a lot of information, not just about Eratosthenes but about the times and the state of science. I sometimes don’t read the preface but this time I’m glad I did. It gave me some insight into how the author approached the topic that I thought it was useful to have. Even though I did find all the information I was reading interesting I did start to wonder when Eratosthenes was going to show up in this book but when he did it became apparent why all the information that came before was necessary. It sets the stage for the feat that Eratosthenes accomplishes. And understanding the world around him and having him firmly placed in a well-defined setting helps you to understand Eratosthenes better. You get to see how Eratosthenes went against convention and popular thought in his pursuit of science and how he was an original thinker in a lot of ways. And you see the impact of his work on those that came after him. Not much in known about Eratosthenes but Nicastro manages to give the reader a wonderful idea of who the man was and why he has been remembered through history.