they were made that way. ours today are very even because we use a different process (layer of molten glass on a layer of molten tin, makes a perfectly smooth sheet of glass) They did not have our technology back then. So their sheets had uneven thickness. Also, some windows are thicker on top, not t the bottom, because they happened to be mounted that way and they did not change shape.
What's the explanation for windows looking like they're melting then?
they were made that way. ours today are very even because we use a different process (layer of molten glass on a layer of molten tin, makes a perfectly smooth sheet of glass) They did not have our technology back then. So their sheets had uneven thickness. Also, some windows are thicker on top, not t the bottom, because they happened to be mounted that way and they did not change shape.