I was given the original Memoire to translate by a now-deceased amateur astronomer (whose name escapes me). When he passed away, I figured I might as well publish it on my old blog.
Here is the link to Leon Foucault’s original article on making parabolic, silvered telescope mirrors from about 1859:

http://books.google.com/books?id=m6Y3AQAAIAAJ&pg=PA197#v=onepage&q&f=false

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