« Waxing lyrical | Main | Pots of fun »
Glass roots
Several of you write to tell us that Jonathon Allport’s point that glass is a fluid is a myth.
‘The reason that the glass in old windows is thicker at the bottom is to do with the process used to manufacture them,’ says Gavin Sinclair. ‘One end was always thicker than the other and it makes sense to install the thick end at the bottom. The glass itself isn’t flowing anywhere.’ Which is a relief.
‘It’s estimated that it takes about 10 million years for the glass at the bottom to be just five per cent thicker,’ adds Barry Wickett, at Techniquest.
‘Windows that are thicker at the top have been found, probably because the workers put them in upside down,’ says Ricky Paltz, at Microdec – which just goes to show that even hundreds of years ago, the best and the brightest didn’t install windows for a living.
Post a comment