Darkwater: Voices from Within the Veil

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Read Books, 2007 - Literary Collections - 288 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 (2007)

Civil rights leader and author, William Edward Burghardt Du Bois was born in Great Barrington, Massachusetts on February 23, 1868. He earned a B.A. from both Harvard and Fisk universities, an M.A. and Ph.D. from Harvard, and studied at the University of Berlin. He taught briefly at Wilberforce University before he came professor of history and economics at Atlanta University in Ohio (1896-1910). There, he wrote The Souls of Black Folk (1903), in which he pointed out that it was up to whites and blacks jointly to solve the problems created by the denial of civil rights to blacks. In 1905, Du Bois became a major figure in the Niagara Movement, a crusading effort to end discrimination. The organization collapsed, but it prepared the way for the founding of the National Association for the Advancement of Colored People (NAACP), in which Du Bois played a major role. In 1910, he became editor of the NAACP magazine, a position he held for more than 20 years. Du Bois returned to Atlanta University in 1932 and tried to implement a plan to make the Negro Land Grant Colleges centers of black power. Atlanta approved of his idea, but later retracted its support. When Du Bois tried to return to NAACP, it rejected him too. Active in several Pan-African Congresses, Du Bois came to know Fwame Nkrumah, the first president of Ghana, and Jono Kenyatta the president of Kenya. In 1961, the same year Du Bois joined the Communist party, Nkrumah invited him to Ghana as a director of an Encyclopedia Africana project. He died there on Aug. 27, 1963, after becoming a citizen of that country.

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