The role of metal in the building
The most primitive form of window openings from the slightest change in the form of, its role is to withstand harsh outdoor lighting and weather at this time of the window material is very rich, from the goatskin parchment, horn linseed oil to thin paper - in fact, Any kind of translucent, light-permeable material can be used for windows .11 century with the construction of Christian churches and the application of a large number of stained glass, the role of windows to become decorative art to render the mystery of religion. before, "grilles" restricted glass production, are correspondingly small pieces of glass embedded into the contour grid fan of it. so this time window function is to shelter from the storm and prevent thieves invasion. until the 17th century late stage, progress with the times, glass industrial production, changes in the relationship between man and nature, people realized that the windows should be purely functional - not only a simple lighting, scenic, shelter from bad weather in the role. during the British disclosure straight edge of formula casement window (i.e. casement); Dutch invention the sash (i.e., pulling up and down the window), the vertical hanging direction of the slide ledge means controlled from a pulley marks. " The birth of window hardware system ".
