In re-building London , after the fire in 1666, no other timber than oak was allowed to be used in roof, door, window frames or cellar floor of any house. - Eleventh Report of the Commissioners Appointed to Enquire into the State and Conditions of the Woods, Forests and Land Revenues of the Crown, 1792.
In the beginning there were no windows. When we lived in trees they weren't really appropriate and caves just had a cavemouth. The iron age round house might typically have had wattle and daub walls and a big thatched roof but what little light got in had to make do with the doorway and a hole in the top that let smoke out as well as light (and rain) in. The central Asian ger or yurt, still lived in by thousands of Mongolians and trendy holiday-makers in England, is similarly window-less. Glass is pretty modern stuff. Well, cast glass vessels were made in Egypt from at least 1500BC and some glass has been found in Mesopotamia a thousand years earlier. The Romans developed a glass industry big time in the first century BC, but most glass was for containers and the rest was more ornament than use. It seems that glass blowing was invented in the Syria or Palestine region and the technique introduced to Rome around the mid first century BC. And then, in the first century AD, they invented the windowpane. Glass panes were used mostly in the windows of bath houses, with examples of both cast and blown glass having been found. They were not at all clear and transparent so it seems they were more for illumination and draught stopping than for the view, but that's appropriate enough for a bathroom. There are some finds of Roman window glass from Britain, mostly of cast glass but it seems that this was being superseded by blown glass in the third century. The northernmost example comes from the Scottish fortress at Inchtuthil.
After the Roman era we had the Dark Ages, so called because windows went seriously out of fashion. Well, perhaps not fashion so much as abject poverty. At best, houses had holes in the walls which were blocked during inclement weather by wooden shutters. Because of the cost of glass, for all but the super-rich and the Church, the Dark Ages actually lasted right through the Medieval Period and only gradually through the 16th and 17th centuries did the humbler hovels get glass in their windows. It was very difficult to make sheets of vaguely flat and clear glass more than a few inches across so windows were made up of lots of little square or diamond shaped pieces held together by H-shaped strips of lead, called came. The whole lot was held together in either an iron frame, common in stone and brick buildings, or a wooden frame, more common in timber houses. These 'leaded lights', born of expedient to necessity, turned out to be regarded as very pretty and so continued to be used for ever, the style being given a particular boost by William Morris and his pre-Raphaelite chums in the 19th century, and most recently seen in the habit of the uPVC glazing industry gluing strips of lead, or even plastic that looks almost like lead, onto their double glazed sealed units. How sad.
Back to the Tudors, while most windows just didn't open, there were basically two ways of opening and closing a window. Either the sash swung on hinges, in which case it is called a casement window, or one sash slid past another, and it can then, sensibly, be called a sliding sash window. With a sliding sash there is a choice of sliding vertically or horizontally. Horizontally, being simpler and less gravity defying, probably came first. Such windows in England are generally called Yorkshire Sashes, doubtless because they are particularly common in Yorkshire. Usually the window is about square, divided into two oblong sashes arranged portrait fashion. One is fixed and the other slides sideways in front, on the indoors side, of the fixed one. It runs between a couple of strips of beading that stop it falling out, except that the beading is not quite long enough so that if the sash is slid all the way it can be removed allowing the outside of the window to be cleaned easily from indoors. There are no moving mechanisms to break, no expensive metal fittings, the sashes don't get in anyone's way when open and the big area that opens allows lots of lovely fresh air when you want it. It really was a very smart design for a window. But because it is simple and cheap it lacked snob-appeal and so remained popular mostly up north, (Yorkshire). Elsewhere, Yorkshire sashes are mostly found round the back of houses or in outbuildings and farmsteads. A larger variant is window about half as long again as it is wide with three sashes. Either the central third is fixed and there are sliding sashes to either side, or the central third slides to right or left in front of fixed sashes at each end.
Then someone had the smart idea of turning the window round, portrait fashion. This allowed more light in without increasing the lintel size and corresponding structural weakening of the wall. The sashes would now have to slide vertically, which is where anti-gravity devices had to be introduced. This started simply with a prop or a wedge to keep the upper sash up, but as anyone with a broken sash cord knows, this is not really satisfactory except where the windows are very small and the sashes therefore not very heavy. Sashes came to be suspended by cords or, with large heavy sashes, by chains, over pulleys and counterbalanced by iron or lead weights housed in a box along each side of the window. Such windows are called top hung or box sashes. Sometimes they are called double hung, to emphasise that both sashes are hung and can slide. Sometimes the can't, with only the top sash being hung and the bottom one just has to be propped if you want to open it. The upright oblong shape of the window that such technology allowed, is a central feature of much Georgian and Victorian architecture. They were probably a Dutch invention, perhaps late in the 16th century. The avid window-spotter is recommended a trip to Delft.
Medieval glass, as we have noted, was made in very small pieces, but gradually the techniques of the industry developed and larger sheets were made. There were three fundamentally different methods of making a sheet of glass, which produced plate, crown, and cylinder glass. Plate glass is really the oldest as this, in a crude form, was the Roman bathroom stuff. Molten glass was poured o to a flat slab of stone of sand covered timber, rolled flat and then , when cooled, the surfaces were laboriously polished. Plate glass got bigger and smoother and flatter as the technology developed until, in the 19th century, very large sheets could be produced. But it was always fabulously expensive and only found in the grandest house windows. Plate glass was the material of choice for mirrors as it did not distort ones face, fairground-fashion.
Crown glass, perhaps first produced in Britain at Crutched Friars in London, in 1557, was made extensively in the 17th and 18th centuries, but is no longer produced on a commercial scale. A mouth blown ball of glass was opened out and flattened into a circular disk by spinning it around. Small sheets could then be cut from the disc leaving a 'bulls eye' or bullion in the centre which was re-melted or sometimes used as glazing in unimportant outhouses and semi-basements. A couple of centuries later fanciful folk put pretend bullions in the windows of pubs and mock-Georgian homes. Old crown glass is a rare and valuable material, interesting to look at with its concentric rings of distortion, it should be cherished with care and affection.
Cylinder glass has almost as long a history as plate, but it was difficult to produce large sheets, flat and of an even thickness. Again, the techniques developed and by the middle of the 19th century sheets its manufacture had been automated so that three feet square with only the slightest of wobbles in them could be produced on an enormous scale to feed the great explosion of urban housing. Small quantities of cylinder glass are still made at factories in France, Germany and Poland by the traditional method of blowing a ball of glass, swinging it around until it elongates into cylinder, cutting it open and allowing it to unroll into a rectangular sheet. It is sold as 'antique glass' and, with the character of its slight imperfections and distortions, looks much more beautiful than the cheaper alternatives.
In Tudor houses, where wealth allowed, quite extensive area came to be glazed. Large stone-mullioned windows in brick and stone houses and casements that occupied the whole space between vertical timbers in framed houses became quite an architectural feature. Craftsmen seemed to get quite carried away at times with the ornamentation of wrought hinges, sash fasteners and stays. Where timber was used oak was the material of choice. It was left unpainted, allowed to weather to a silvery grey gradually darkening over the years. Its strength and durability is proved by the survival of 500 year old window frames, still in serviceable condition.
In the 17th and 18th centuries, supplies of oak gradually dwindled and were replaced by pine imported from Scandinavia. As the 'Georgian' type top hung sash windows replaced the casements so pine replaced oak. It was a timber of considerable durability, being slowly grown with a count of twenty or more growth rings to the inch, quite unlike the 'whitewood' found in the modern DIY sheds. Nevertheless, its introduction coincided with that of paint. And this was linseed oil paint with lead pigment, a tough , flexible, durable yet breathable material that provided a much better timber protection than the paints inn common use today. The small glass pieces used in leaded lights gave way to larger rectangles of crown glass held by wooden glazing bars. These started quite robust and plain with windows of the Queen Anne period often having glazing bars of 35 or 40 mm width. A trend to narrower glazing bars developed with a decorative moulding on the inside and a narrow wedge of putty to fix the glass on the outside. Bars were reduced to around 18mm and when chrome pigments were produced in the early 19th century dark green paint replaced the earlier white to make the glazing bars all but invisible from a distance.
The source of our word window is a vivid metaphor. Window comes to us from the Scandinavian invaders and settlers of England in the early Middle Ages. Although we have no record of the exact word they gave us, it was related to Old Norse vindauga, “window,” a compound made up of vindr, “wind,” and auga, “eye,” reflecting the fact that at one time windows contained no glass. The metaphor “wind eye” is of a type beloved by Norse and Old English poets and is called a kenning; other examples include oar-steed for “ship” and whale-road for “sea.” Answers.com
Thus rises on high the deep bosomed vault, borne above
triple voids below; and through five-fold openings, pierced in its back, filled
with thin plates of glass, comes the morning light scattering sparkling rays.
Paul the Silentiary, Ode to S. Sophia recited at the dedication of
the Constantinople church in AD 563.
1845 Abolition of Glass Tax
1851 Abolition of Window Tax
1905 Belgium. Emile Fourcault vertically drew a continuous sheet of glass of a consistent thickness from the tank. Commercial production of drawn sheet glass using the Fourcault process started in 1914.
1914 Belgium. Emil Bicheroux developed a process whereby molten glass was poured directly through two rollers. Such rolled glass also produced an even thickness, and made grinding and polishing easier and more economical.
1910 France. Edouard Benedictus patented laminated glass with a layer of celluloid between two sheets of glass with the name ‘Triplex’.
1917 USA. Colburnat at glass-makers Libbey-Owens, improved the drawn glass sheet process and went into commercial production.
1928 USA. Pennvernon at the Pittsburgh Plate Glass Company (PPG), combined and enhanced the Fourcault and Libbey-Owens processes.
1959 England. Pilkington introduced the float process in, combined the brilliant finish of sheet glass with the optical qualities of plate glass. Molten glass was poured across a surface of molten tin and drawn horizontally in a continuous ribbon.
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