Fact Check

The Ptolemy Book

The Sleuth agents are sent to Genoa, Italy to find an ancient geography book used by Columbus. In Italy they discover the book, complete with Columbus notes written in the margins.

Where Did Columbus Get His Information?

Columbus used many books and other documents to help calculate the size of the globe and the distance across the ocean. He taught himself other languages including Portuguese, Spanish, and Latin. He collected books with information from ancient Greek and Roman authors.

The Ptolemy book that Ava finds in Lost Treasure Hunt is based on real life books owned by Columbus, but does not perfectly match any of the books Columbus used.

Who was Ptolemy?

Ptolemy (pronounced with a silent P: “Tol-emy”) was a Greek author who lived in the Roman Empire during the 2nd century AD. He created an extraordinary book about the size and shape of the continents – so extraordinary that it was still being used over a thousand years later by scholars during the time of Columbus.

A copy Ptolemy’s Geography, believed to have been owned by Columbus, still exists today in the Real Academia de la Historia in Madrid, Spain. The book contains the Columbus signature, but does not have notes in the margins.

Notes Written by Columbus in His Own Books

So why does Ava in Lost Treasure Hunt come across a version of the book that has notes in the margin? In fact there is a collection of books owned by Columbus which contain many notes similar to this which most historians believe are handwritten notes by Columbus himself. Among these books with Columbus notes are Il Milione (the Travels of Marco Polo) and Imago Mundi (another geography book which has the most Columbus notes of all of the books). By examining these notes, it is easy to imagine Columbus carefully looking for information that would help prove he could sail to Asia by traveling west. These books can be found today in Seville, Spain.

How Did These Books End Up in Seville?

After Christopher Columbus died, his son Hernando (sometimes called Ferdinand) carefully preserved his father’s collection. Hernando had a great interest in books, and even wrote some as well, including a biography of his father that is one of the most important books we have about Columbus. Unfortunately Christopher Columbus’ grandson Luis, who later inherited Columbus’ books, did not have the same appreciation. Many books were ruined, sold, or lost until the remaining books were given to the Seville Cathedral where they remain to this day as part of the Biblioteca Colombina where visitors can study some of the books once used by Columbus.

Sources and Further Reading


Fernández-Armesto, F. (1991). Columbus. Oxford: Oxford University Press, p.35

Taviani, P. E. (1985). Christopher Columbus: The grand design. London: Orbis, p.449-450

European images of the Americas and the classical tradition. (1994). Berlin: Walter de Gruyter, p.121


* Roop, P., & Roop, C. (2000). In Their Own Words: Christopher Columbus. New York: Scholastic, p.26-32

* Feinstein, S. (2010). Columbus: Opening up the new world. Berkeley Heights, NJ: Enslow, p.41-44.

* Dodge, S. (1991). Christopher Columbus and the first voyages. New York: Chelsea House, p.18, 47-53.


* Young Reader's Selection