Those that have been edited, reprinted in facsimiles, or transferred to microfilm can be borrowed through E-ZBorrow or Interlibrary Loan if they are not in Tripod. Many of them will be listed in Tripod or WorldCat under subject terms and the word "sources." For example, the search latin america* history sources produces books including:
Books printed in the 17th and 18th centuries are kept in libraries' rare book collections. Sometimes 19th cetury titles are also treated as rare. You can go to Haverford's Special Collections, Bryn Mawr, the University of Pennsylvania, and other local libraries to see examples of these books:
The natvrall and morall historie of the East and West Indies
By Acosta, José de, 1540-1600.
London, Printed by V. Sims for E. Blount and W. Aspley, 1604
H Magill Special Collections E141 A25
Anecdotes of Africans
H Magill Special Collections BX7642 A57