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spectroheliograph

(Encyclopedia)spectroheliograph, device for photographing the surface of the sun in a single wavelength of light, usually one corresponding to a chief element contained in the sun, e.g., hydrogen or calcium; the re...

peritonitis

(Encyclopedia)peritonitis pĕrˌĭtənīˈtĭs [key], acute or chronic inflammation of the peritoneum, the membrane that lines the abdominal cavity and surrounds the internal organs. It is caused by invasion of bac...

plaid

(Encyclopedia)plaid, a long shawl or blanketlike outer wrap of woolen cloth, usually patterned in checks or tartan figures. Now a distinctive feature of the Highland costume, it was formerly worn in all parts of Sc...

pleurisy

(Encyclopedia)pleurisy plo͝orˈĭsē [key], inflammation of the pleura (the membrane that covers the lungs and lines the chest cavity). It is sometimes accompanied by pain and coughing. The inflammation may be dry...

bloodletting

(Encyclopedia)bloodletting, also called bleeding, practice of drawing blood from the body in the treatment of disease. General bloodletting consists of the abstraction of blood by incision into an artery (arterioto...

colloid

(Encyclopedia)colloid kŏlˈoid [key] [Gr.,=gluelike], a mixture in which one substance is divided into minute particles (called colloidal particles) and dispersed throughout a second substance. The mixture is also...

rudder

(Encyclopedia)rudder, mechanism for steering an airplane or a ship. In ships it is a flat-surfaced structure hinged to the stern and controlled by a helm. When the ship is on a straight course, the rudder is in lin...

Chrysophyta

(Encyclopedia)Chrysophyta krəsŏfˈətə [key], phylum (division) of unicellular marine or freshwater organisms of the kingdom Protista consisting of the diatoms (class Bacillariophyceae), the golden, or golden-br...

opal

(Encyclopedia)opal ōˈpəl [key], a mineral consisting of poorly crystalline to amorphous silica, SiO2·nH2O; the water content is quite variable but usually ranges from 3% to 10%. Common opal is usually colorless...

stratification

(Encyclopedia)stratification (Lat.,=made in layers), layered structure formed by the deposition of sedimentary rocks. Changes between strata are interpreted as the result of fluctuations in the intensity and persis...