Crown glass is either of two kinds of glass. The physics definition of a glass is a uniform amorphous solid material, usually produced when a suitably viscous molten material cools very rapidly, thereby not giving enough time for a regular crystal lattice to form. ...

One type comes from the way window glass was first made. Glass was blown into a crown or hollow globe that is then flattened and cut. It is flattenned by reheating and spinning out the bowl-shaped piece of glass (bullion) into a flat disk by centrifugal force, up to 5 or 6 feet in diameter. The glass is then cut into the size required, because of the manufacturing process the best, thinnest, glass is in a band at the edge of the disk, with the glass becoming thicker and more distorting towards the centre. Due to the distribution of the best glass, in order to fill large window spaces many small diamond shapes would be cut from the edge of the disk and these would be mounted into a lead lattice work and fitted in the window.

Crown glass was one of the two most common processes for making glass for windows up until the 19th century, the other was blown plate. The process was first perfected by French glassmakers in the 1320s, notably around Rouen. The process was kept a careful trade secret, for example the first crown glass made in London was not until 1678. Compare to polished plate, cylinder sheet, rolled plate, and float glass. Location within France Rouen (pronounced in French, sometimes also ) is the historical capital city of Normandy, in northern France, and presently the capital of the Upper Normandy région. ... Float glass is made by melting glass and feeding a thin layer onto a tank of molten tin in a nitrogen atmosphere. ...

The second use of the phrase is for a type of optical glass used in compound lenses. This Crown glass is produced from a special alkali-lime silicate incorporating a high amount of phosphorus pentoxide, it has a low refractive index and low dispersion (high Abbe number). A lens is a device for either concentrating or diverging light, usually formed from a piece of shaped glass. ... The refractive index of a material is the factor by which electromagnetic radiation is slowed down (relative to vacuum) when it travels inside the material. ... In optics, dispersion is a phenomenon that causes the separation of a wave into spectral components with different frequencies, due to a dependence of the waves speed on its frequency. ... In physics and optics, the Abbe number, also known as the V-number or constringence of a transparent material is a measure of the materials dispersion (variation of refractive index with wavelength). ...

The first recorded use of crown glass in windows was at the Banqueting House at the Palace of Whitehall, London, in 1685. Highly decorative Window in a Japanese Onsen in hakone A window is an opening in an otherwise solid, opaque surface through which light can pass. ... Banqueting House, Whitehall, London The Banqueting House at Whitehall is a famous London building, formerly part of the Palace of Whitehall, designed by architect Inigo Jones in 1619, and completed in 1622, with assistance from John Webb. ... The Palace of Whitehall was the main residence of the English monarchs in London from 1530 until 1698 when all except Inigo Jones 1622 Banqueting House was destroyed by fire. ... Greater London and the Regions of England. ... Events February 6 - James Stuart, Duke of York becomes King James II of England and Ireland and King James VII of Scotland. ...