How did newton grind his lenses?

Question

I read in an article about Newton that he ground his own optical lenses. I wonder how people in the 1700's would go about that. How does one make a lens without any precision machinery?

Answer 1

Even today, amateur astronomers grind their own mirrors and lenses -- using the exact same techniques and most of the same materials they had centuries ago.

Here is a place that sells whole kits of materials and instructions for how to do it just like Newton did.

http://www.newportglass.com/achromat.htm

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Answer 2

Believe it or not, machinery with it's patterns has a harder time grinding a superb telescope mirror than a human sitting at a table rubbing 2 glass discs with grinding grit between them against each other.  Google "telescope mirror grinding" and if you're the type, prepare for a new hobby.