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Alton

(Encyclopedia)Alton ôlˈtən [key], city, Madison co., SW Ill., on bluffs of the Mississippi River 5 mi (8.1 km) above its confluence with the Missouri; inc. 1837. Alton is a shipping ...

turquoise

(Encyclopedia)turquoise, hydrous phosphate of aluminum and copper, Al2(OH)3PO4·H2O+Cu, used as a gem. It occurs rarely in crystal form, but is usually cryptocrystalline. Turquoise is opaque and has a waxy luster; ...

automatic tuning control

(Encyclopedia)automatic tuning control (ATC), method or device to keep a radio or television receiver automatically tuned to a desired frequency or channel. Assuming that the receiver is at least approximately tune...

palmtop

(Encyclopedia)palmtop or hand-held personal computer, lightweight, small, battery-powered, general-purpose programmable computer. It typically had a miniaturized full-function, typewriterlike keyboard for input and...

cast-iron architecture

(Encyclopedia)cast-iron architecture, a term used to designate buildings that incorporate cast iron for structural and/or decorative purposes. After 1800 cast-iron supports were exploited as an alternative to mason...

symmetry

(Encyclopedia)symmetry, generally speaking, a balance or correspondence between various parts of an object; the term symmetry is used both in the arts and in the sciences. In art and design, it is often used in a s...

Kent, cities, United States

(Encyclopedia)Kent. 1 Industrial city (1990 pop. 28,835), Portage co., NE Ohio; settled in 1805 as Franklin Mills, combined with Carthage and renamed as Kent 1863, inc. as a city 1920. Machinery and processed foods...

flint, mineral

(Encyclopedia)flint, variety of quartz that commonly occurs in rounded nodules and whose crystal structure is not visible to the naked eye. Flint is dark gray, smoky brown, or black in color; pale gray flint is cal...

Rochelle salt

(Encyclopedia)Rochelle salt, colorless to blue-white orthorhombic crystalline salt with a saline, cooling taste. It is also called Seignette salt after Pierre Seignette, an apothecary of La Rochelle, France, who wa...

prism

(Encyclopedia)prism, in optics, a piece of translucent glass or crystal used to form a spectrum of light separated according to colors. Its cross section is usually triangular. The light becomes separated because d...