Drilling old glass?

[plutoniumJoe]

Originally Posted by bvlester

Glass is always in motion although very slow ove time glass from the top of a window runs down to the bottom,

Bill

This is a common misunderstanding. Often people state that glass is not solid but a super cooled liquid. Silica's melting point is around 1200C and temperatures between 10-even as high as 40C are so far away that even if Glass was not truly crystallized the time it would take for glass to flow to a noticeable difference is beyond a human time frame. The better explanation for thicker glass at the bottom of old buildings or ancient churches is the actual glass production process and glaziers preferences of setting glass with the heavier side at the bottom.