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.
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1508-1555
Dutch mathematician and mentor of Gerhard Mercator (1512-1594) who provided the first published illustration of a camera obscura, and who advanced attempts at solving the longitude problem. At that time, navigators were still many years away from finding a means of easily and accurately measuring longitude, a challenge that literally posed a life-and-death problem to sailors at sea. Frisius's De principiis astronomiae cosmographicae (1530) discussed a method for finding longitude using a clock and astrolabe. During the 1530s, he trained Mercator, and in 1545 published De radio astronomico et geometrico, which discusses his observations of a solar eclipse the preceding January. The book included a drawing of the camera obscura, a dark, enclosed chamber that was a forerunner of the modern camera.