Claudius Ptolemaeus or Ptolemy lived in Alexandria, Egypt from approximately 87 -150 AD. He was an astronomer, mathematician and geographer.

One of his major works was Geographia, a thesis totaling eight books. It attempted to map the known world giving coordinates of the major places in terms of latitude and longitude. Unfortunately, Ptolemy’s maps were incorrect in many places because of a lack of accurate data. For example, by extending the coast of China southward, his maps limited the awareness of the Pacific Ocean.

However, Ptolemy’s maps were used by travelers for hundreds of years and it is believed that Christopher Columbus sailed with them when he discovered America in 1492 in his mistaken belief that he had pioneered a new route to India.

 

Courtesy of the Wikipedia encyclopedia http://en.wikipedia.org/wiki/Ptolemy