This is one of the best all around sites that I have found. It is titled “The MacTutor History of Mathematics Archive.”
http://www-history.mcs.st-and.ac.uk/~history/
This is an award-winning site that links to all sorts of mathematics information.
http://archives.math.utk.edu
Galois:
http://www-history.mcs.st-and.ac.uk/~history/Mathematicians/Galois.html
Cauchy:
http://www-history.mcs.st-and.ac.uk/~history/Mathematicians/Cauchy.html
Fourier:
http://www-history.mcs.st-and.ac.uk/~history/Mathematicians/Fourier.html