File:Elements of astronomy with explanatory notes, and questions for examination (1855) (14759558706).jpg

Identifier: elementsofastro00broc (find matches)
Title: Elements of astronomy ... with explanatory notes, and questions for examination
Year: 1855 (1850s)
Authors: Brocklesby, John, 1811-1889
Subjects: Astronomy
Publisher: New York, Farmer, Brace & co.
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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ertainthe dimensions of a stick of timber he does so by meansof a rule, the length of which he knows, and thus heobtains the solidity of the log in feet and inches. When, likewise, we wish to determine the speed of alocomotive, we measure by the aid of a watch the timetaken to pass over a known number of miles. Thus un-known magnitudes and motions are ascertained by com-paring them with such as are known. In astronomical investigations we pursue a like course,and begin with determining the size, motions, and formof the Earth, with other important particulars that arewithin our reach. We thus obtain fixed standards of 1. Asteroids. From two Greek words, aster, a star, and eidos, like.Like a star, because all these planets are very small. 2. Orbit means the path of a planet about the sun. So called from theLatin word, orbis, a circle, a circuit. What are the Asteroids, and where situated 1 Explain the figure. In what mannerare astronomical investigations conducted 7 16 ASTRONOMY.FIG. 1.
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SOLAR SYSTEM. EXPLANATORY CHAPTER. 17 measurement, whereby we are enabled to push our in-quiries beyond the earth, and to compute the distances,times, motions, and velocities of many of the bright orbs1that glitter about us, and the extent of the vast spacesthrough which they move. In the study of Astronomyour attention is, therefore, directed First to the Earth inits relation to the rest of the heavenly bodies. Secondly,to the Solar System. Thirdly, to the Starry Heav-ens, of which this system is a part. EXPLANATORY CHAPTER. 10. In learning Astronomy it is necessary for thepupil at the outset to know the meaning of certainmathematical and philosophical terms and expressions,which are constantly occurring in the discussion of as-tronomical subjects. These must be mastered in orderto obtain a clear understanding of the science, and yetthey are by no means difficult to comprehend. Themost important of these are explained in the presentchapter. The meaning of other terms and phrases will

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