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.
The drill, which dates back to the Stone Age, was first used to start fires. A slender piece of wood was rotated between the hands to create a flame, through friction. This device became the bow drill by the addition of a bow-shaped stick and a simple cord attachment that allowed for increased rotation.
As early as the eighth century B.C., drills were used by the Greeks for hole-cutting, and this remains their primary purpose today. By the third century B.C., the Chinese found that drills could be used to bore through the earth to tap oil deposits. Heavy drilling through rock was accomplished by means of metal or weighted attachments to systematically pound and penetrate.
Drills developed little until well into the nineteenth century. They were most extensively used in clockmaking, an application which required only that the drill bit be sharp enough to puncture thin metal. The clockmaker's drill press was operated either by hand crank or foot treadle. In 1835, Joseph Whitworth, a British mechanical engineer, introduced a heavy-duty vertical drill that represented a huge advance over previous presses in both speed and stability. Innovations that followed included the portable electric drill, the radial drill (for aligned drilling over large surfaces), and the pneumatic drill (especially useful for tunneling work).
Lightweight cordless drills have severed the link to the electrical outlet and offer easy use in almost any situation. Improvements in the nickel-cadmium battery technology used in these tools, and other design refinements have made the cordless drill the most popular of cordless tools.
Drill bits typically contain spiral-shaped grooves, though some bits have straight cutting edges. These grooves enable waste material to be channeled away from the cutting surface. Closely related to the drill is the boring machine. Together these two machine tools facilitate the manufacture and assembly of countless objects of varying shape, size, and use.