-
1 Ravenscroft, George
[br]b. 1632 Alconbury, Huntingdonshire, Englandd. 7 June 1683 Barnet, Hertfordshire, England[br]English inventor of lead-crystal glass.[br]George's father James was a successful lawyer and merchant, engaging in overseas trade.A devout but necessarily circumspect Catholic, James sent his sons to the English College at Douai, now in northern France. Leaving there in 1651, George began to learn his father's business and spent some fifteen years in Venice. He took an increasingly important part in it, doubtless dealing in Venice's leading products of lace and glass. By 1666 he was back in England and, perhaps because the supply of Venetian glass was beginning to decline, he started to manufacture glass himself. In 1673 he set up a glassworks in the Savoy in London and succeeded so well that in the following year he petitioned the King for the grant of a patent to make glassware. This was granted on 16 May 1674, stimulating the Glass Sellers' Company to enter into an agreement with Ravenscroft to buy the glassware he produced. Later in 1674 the company allowed Ravenscroft to establish a second glasshouse at Henley-onThames. At first his ware was beset with "crizzling", i.e. numerous fine surface cracks. The Glass Sellers probably urged Ravenscroft to cure this defect, and this he achieved in 1675 by replacing crushed flint with increasing amounts of lead oxide, rising finally to a content of 30 per cent. He thereby obtained a relatively soft, heavy glass with high refractive index and dispersive power. This made it amenable to deep cutting, to produce the brilliant prismatic effects of cut glass. At about the same time, the Duke of Buckingham, a considerable promoter of the glass industry, agreed that Ravenscroft should manage his works at Vauxhall for the making of plate glass for mirrors. Ravenscroft terminated his agreement with the Glass Sellers in 1678, the date of the last evidence of his activities as a maker of crystal glass, and the patent expired in 1681. His new glass had immediately rivalled the best Venetian crystal glass and has been a valued product ever since.[br]Further ReadingR.F.Moody, 1988, The life of George Ravenscroft', Glass Technology 29 (1):198–210;Glass Technology 30(5):191–2 (additional notes on his life).LRD -
2 Chemical technology
-
3 Photography, film and optics
See also: INDEX BY SUBJECT AREA[br]Ding HuanGabor, DennisKlic, KarolLippershey, HansMarton, LadislausTournachon, Gaspard FélixBiographical history of technology > Photography, film and optics
См. также в других словарях:
Ravenscroft, George — ▪ English glassmaker born 1618 died 1681 English glassmaker, developer of flint glass, a heavy, blown type (shaped by blowing when in a plastic state) characterized by both brilliance and dark shadow. Ravenscroft was commissioned by… … Universalium
George Ravenscroft — (1632 7 June 1683) was an English businessman in the import/export and glass making trades. He is primarily known for his work in developing clear lead crystal glass (also known as flint glass) in England.Personal lifeLittle is known about… … Wikipedia
Ravenscroft — is a surname, and may refer to* Edward Ravenscroft, an English dramatist * Edward James Ravenscroft (1816 1890), author of Pinetum Britannicum * George Ravenscroft (1632 1683), developer of lead crystal glass in England * John Ravenscroft *… … Wikipedia
George Baker (actor) — Infobox actor bgcolour = name = George Baker imagesize = caption = birthname = birthdate = birth date and age|1931|04|1 location = Varna, Bulgaria deathdate = deathplace = occupation = Actor spouse = Louie Ramsay (1993 Present) Sally Home (1974… … Wikipedia
John Stark Ravenscroft — (1772 1830) was the first Bishop of the Episcopal Diocese of North Carolina. LifeBorn near Blandford in Prince George County, Virginia in 1772, his early life was spent in Scotland. Ravenscroft did not decide on any profession until he was 27,… … Wikipedia
Thurl Ravenscroft — Infobox actor bgcolour = silver name = Thurl Ravenscroft caption= Ravenscroft s 1970 gospel album Great Hymns in Story and Song imagesize = birthdate = birth date|1914|2|6|mf=y location = Norfolk, Nebraska, U.S. height = deathdate = death date… … Wikipedia
Edward Ravenscroft — (1654? ndash;1707), English dramatist, belonged to an ancient Flintshire family. He was entered at the Middle Temple, but devoted his attention mainly to literature. Among his pieces are * Mamamouchi , or The Citizen turned Gentleman (Dorset… … Wikipedia
Lead glass — Swarovski flacon. Lead glass is a variety of glass in which lead replaces the calcium content of a typical potash glass.[1] Lead glass contains typically 18–40 weight% lead(II) oxide (PbO), while modern lead … Wikipedia
glassware — /glas wair , glahs /, n. articles of glass, esp. drinking glasses. [1705 15; GLASS + WARE1] * * * Introduction any decorative article made of glass, often designed for everyday use. From very early times glass has been used for various… … Universalium
flint glass — Optics. an optical glass of high dispersion and a relatively high index of refraction, composed of alkalis, lead oxide, and silica, with or without other bases, sometimes used as the diverging lens component of an achromatic lens. [1665 75] * * * … Universalium
industrial glass — Introduction solid material that is normally lustrous and transparent in appearance and that shows great durability under exposure to the natural elements. These three properties lustre, transparency, and durability make glass a favoured… … Universalium
