Amerigo Vespucci was an Italian explorer, financier, navigator and cartographer who lived from March 9, 1454 to February 22, 1512.  He was the first to demonstrate that Brazil and the West Indies were not, after all, the eastern boundaries of Asia but a separate land mass from the Old World.  This New World came to be known as the Americas deriving from Vespucci’s first name.

Through the intrigues of Bishop Juan Rodriguez de Fonseca, Castile broke it’s deal with Columbus in April of 1495.  Thereafter, it handed out licenses to other navigators for the West Indies.  One of these was given to Giannotto Berardi who passed away before fulfilling his contract to provide 12 vessels to voyage to the Indies.  Vespucci was executor for Berardi’s estate.  As such, he stepped up to fulfill this obligation.  Following this he continued as a provision contractor for expeditions to and from the Indies.

Between  1499 and 1502, at the invitation of King Manuel I of Portugal, Vespucci participated as an observer on several voyages that explored the east coast of South America.  On these voyages it was discovered that South America extended further than had been thought.  In the process, accounts that may or may not have been written by Vespucci were published culminating in Martin Waldseemuller’s publishing a world map giving the new continent its name, America.

Vespucci’s account may be read here:

http://www.bartleby.com/43/3.html

Alternatively, you may listen to his letter in audiobook format here: