An Elementary Treatise on Astronomy: In Four Parts. Containing a Systematic and Comprehensive Exposition of the Theory, and the More Important Practical Problems; with Solar, Lunar, and Other Astronomical Tables. Designed for Use as a Text-book in Colleges and Academies

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Wiley & Putnam, 1839 - 373 pages
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Page 78 - The areas described by the radius vector of a planet are proportional to the times. 2░. The orbit of a planet is an ellipse of which the center of the sun is one of the foci, 3░.
Page 15 - LONGITUDE of a place, in geography, is an arch of the equator, intercepted between the first meridian and the meridian passing through the...
Page 26 - ... or 7% 7, &c. according to its apparent relative distance from the wire. This kind of observation must be made at each of the five wires, and a mean of the whole taken, which will represent the time of the star's passage over the mean or meridional wire. The utility of having five wires instead of the central one only, will be readily understood, from the consideration that a mean result of several observations is deserving of more confidence than a single one ; since the chances are, that an...
Page 24 - ... motion to the Y before spoken of, and consequently to the pivot of the axis which it carries. Having thus again bisected the object, reverse the axis as before, and if half the error was correctly estimated, the object will be bisected upon the telescope being directed to it; if not quite correct, the operation of reversing and correcting half the error, in the same manner, must be gone through again, until, by successive approximations, the object is found to be bisected in both positions of...
Page 82 - NODE, (1) in astronomy, the two points in which the orbit of a planet intersects the plane of the ecliptic; the one through which the planet passes from the south to the north side of the. ecliptic being called the ascending node, and the other the descending node.
Page 106 - Any two bodies in the universe attract each other with a force that is directly proportional to their masses and inversely proportional to the square of their distance apart...
Page 24 - Y's, and replace it with the axis reversed ; point the telescope again to the same object, and if it be still bisected, the collimation adjustment is correct; if not, move the wires one half the error, by turning the small screws which hold the diaphragm near the eye-end of the telescope, and the adjustment will be accomplished ; but, as half the deviation may not be correctly estimated in moving the wires, it becomes necessary to verify the adjustment by moving the telescope...
Page 23 - One of the grooves is horizontal, the other vertical, so that, by means of screws, one end of the axis may be pushed a little forwards or backwards, and the other end may be either slightly depressed or elevated. Which two small* movements are necessary, as it will be soon explained, for two adjustments of the telescope. Let E be called the eastern pillar, W the western. On the eastern end of the axis is fixed (so that it revolves with the axis) an index n, the upper part of which, when the telescope...
Page 135 - XIII, by the omission of 10 nominal days after the 4th of October, 1582, so that the next day was called the 15th and not the 5th. This change was immediately adopted in all Roman Catholic countries, but tardily in the countries of Protestantism. In England, the change of style...
Page 365 - Art. 243, p. 101), we may vary the enunciation of Kepler's problem, and state its object to be the finding of the true anomaly in terms of the mean. Besides the mean and true anomalies, there is a third called the Eccentric Anomaly, which is...

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