Essays

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Read Books, 2008 - Education - 616 pages
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1902 Excerpt: ...earth. r' = radius of moon, or other body. P = moon's horizontal parallax = earth's angular semidiameter as seen from the moon. f = moon's angular semidiameter. Now = P (in circular measure), r'-r = r (in circular measure);.'. r: r':: P: P', or (radius of earth): (radios of moon):: (moon's parallax): (moon's semidiameter). Examples. 1. Taking the moon's horizontal parallax as 57', and its angular diameter as 32', find its radius in miles, assuming the earth's radius to be 4000 miles. Here moon's semidiameter = 16';.-. 4000::: 57': 16';.-. r = 400 16 = 1123 miles. 2. The sun's horizontal parallax being 8"8, and his angular diameter 32V find his diameter in miles. ' Am. 872,727 miles. 3. The synodic period of Venus being 584 days, find the angle gained in each minute of time on the earth round the sun as centre. Am. l"-54 per minute. 4. Find the angular velocity with which Venus crosses the sun's disc, assuming the distances of Venus and the earth from the sun are as 7 to 10, as given by Bode's Law. Since (fig. 50) S V: VA:: 7: 3. But Srhas a relative angular velocity round the sun of l"-54 per minute (see Example 3); therefore, the relative angular velocity of A V round A is greater than this in the ratio of 7: 3, which gives an approximate result of 3"-6 per minute, the true rate being about 4" per minute. Annual ParaUax. 95. We have already seen that no displacement of the observer due to a change of position on the earth's surface could apparently affect the direction of a fixed star. However, as the earth in its annual motion describes an orbit of about 92 million miles radius round the sun, the different positions in space from which an observer views the fixed stars from time to time throughout the year must be separated ...

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About the author (2008)

Known primarily as the leader of the philosophical movement transcendentalism, which stresses the ties of humans to nature, Ralph Waldo Emerson, American poet and essayist, was born in Boston in 1803. From a long line of religious leaders, Emerson became the minister of the Second Church (Unitarian) in 1829. He left the church in 1832 because of profound differences in interpretation and doubts about church doctrine. He visited England and met with British writers and philosophers. It was during this first excursion abroad that Emerson formulated his ideas for Self-Reliance. He returned to the United States in 1833 and settled in Concord, Massachusetts. He began lecturing in Boston. His first book, Nature (1836), published anonymously, detailed his belief and has come to be regarded as his most significant original work on the essence of his philosophy of transcendentalism. The first volume of Essays (1841) contained some of Emerson's most popular works, including the renowned Self-Reliance. Emerson befriended and influenced a number of American authors including Henry David Thoreau. It was Emerson's practice of keeping a journal that inspired Thoreau to do the same and set the stage for Thoreau's experiences at Walden Pond. Emerson married twice (his first wife Ellen died in 1831 of tuberculosis) and had four children (two boys and two girls) with his second wife, Lydia. His first born, Waldo, died at age six. Emerson died in Concord on April 27, 1882 at the age of 78 and is buried in Sleepy Hollow.

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