The following sites will help you through your research of Thales and his Accomplishments.
Thales
http://www-gap.dcs.st-and.ac.uk/~history/Mathematicians/Thales.html
The Internet Encyclopedia of Philosophy: Thales
http://www.utm.edu/research/iep/t/thales.htm
The Life of Thales
http://www2.forthnet.gr/presocratics/thaln.htm#Kirk