The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
Anemometers are devices which measure the velocity of the wind. The type most commonly in use today consists of three or four cups radiating from the top of a spindle; the cups catch the wind from any direction. The wind speed is either displayed on a dial at the base of the spindle or is recorded at a remote location on a clock-driven drum (anemograph). The earliest anemometers date from the 1400s and consisted of a swinging plate suspended from an axis. The plate would swing vertically in a quarter-circle across a fixed indicator as the wind would blow against it. Other types of anemometers developed were the normal-plate anemometer which used a spring-balanced plate. There was also the pressure-tube anemometer--wind blowing into the lower open end of the tube would move mercury upward in the closed end, which had indicating marks much like a thermometer. A type of anemometer employing this principle but using water was made by Dr. James Lind of England in 1776. Robert Hooke, an English scientist, developed the first practical recording anemometer with a rotating drum in 1644. It was part of a "weather clock" which also recorded the temperature, rainfall, humidity, and barometric pressure. All anemometers, old and current, share a common principle: an indicator reacting physically or electronically to a mechanical device subjected to pressure from air movement.