SCRAPER

in music, percussion instrument consisting of a serrated surface that is rasped with a stick. Known since the Stone Age, it is often associated with magical powers and ritual, and is widely distributed geographically. Scrapers are commonly made of bonee.g., the Aztec omichicahuaztli used in memorial rites; gourd, such as the guiro of Mexican, Cuban, and Brazilian folk music and Latin-American dance bands; wood, as in the Chinese y, or wooden tiger, used in Confucian ritual; horn, as in the charrasca (also called guiro) of Venezuelan folk music; and shell. They are sometimes resonated over a hole or a gourd. The cog rattle, or ratchet, is a more complex scraper, consisting of a cog wheel set in a frame to which a flexible tongue is attached; when the wheel revolves on its axle, the tongue scrapes the cogs. Found in Europe and Asia, cog rattles often served as signal instruments (in World War II, to warn of gas attack) or had ritual use (in medieval Roman Catholic services during the week before Easter). They are now common as toys and as festive noisemakers (a remnant of practices of creating a clamour to frighten away evil spirits). Richard Strauss scored for cog rattle in his symphonic poem Till Eulenspiegel (1895) and Igor Stravinsky for guiro in The Rite of Spring (1913). in engineering, machine for moving earth over short distances (up to about two miles) over relatively smooth areas. Either self-propelled or towed, it consists of a wagon with a gate having a bladed bottom. The blade scrapes up earth as the wagon pushes forward and forces the excavated material into the wagon. When the wagon is filled, the gate is closed, and the material is carried to the place of disposal. The scraper is the dominant tool in highway construction.