“Zetetic Astronomy – Earth Not a Globe! An Experimental Inquiry Into the True Figure of the Earth, Proving It a Plane, Without Orbital or Axial Motion, and the Only Known Material World” (They liked really long titles back in the 19th century) by Dr. Samuel Rowbotham was the most famous and influential flat Earth book of its time. Here it is in its entirety:

http://www.sacred-texts.com/earth/za/