Here are a couple of Youtube clips on making spectacles from scratch..... AS you will have seen....having spare spectacles is much easier than making them from scratch from raw materials. I am fortunate in being slightly long sighted...I can get by with magnifying spectacles for close range work.
after heating in the kiln for several days... I wonder how much glasses cost in 1800 if compared to today's money
The classic way to grind a lens uses two round glass blanks. the lower blank is spun while the top blank is moved across and back at a regular rate. Some sort of abrasive fluid is used between them. Over time one will be come concave and the other convex. There used to be a great video on this, but I can't find it. This one uses one preformed blank and a piece of ceramic to polish it in orcer to make a telescope reflector, but follows the same basic process: And this one shows the same process with manual rotation by periodically moving the glass blank. Seems you could use a treadle type pottery wheel if you needed rotation but didn't have power.
