An Historical Account of the Origin and Progress of Astronomy: With Plates Illustrating, Chiefly, the Ancient Systems
Baldwin and Cradock, 1833 - 520 Seiten
Includes chapters on early constellation observations, ancient astronomers of China and more, €this volume details the history of astronomy from its beginning to the early 1800s.
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according ancient angle appear ascertained assigned astronomer attraction axis bodies called cause celestial bodies centre circle circumference coincide computed concerning consequently considered constellation contained correct described determined diameter direction distance earth eccentric ecliptic Egyptians elements employed epicycle equal equator equinoctial equinox error evident existence expressed fact figure fixed stars follow force formed former given Greeks heavens Hindus Hipparchus hypothesis imagined inequalities interval known latitude latter learned length light longitude lunar manner mean measured mentioned meridian moon moon's motion move movements nature nearly observations obtained opinion opposite orbit origin period phenomena philosopher planets points position present principal probably produced proportion Ptolemy reason relates remarkable represent respect retrograde revolve rising seems setting shew situated solar sphere stars sun's supposed surface tables theory tion true universe variations zodiac
Seite 379 - AE fore the strain at D will be — ~ — x BD. Had the beam been lying horizontally, the strain at D, from the weight W suspended at C, would have been — -—- — X BD. It is therefore diminished in the proportion of AC to AE, that is, in the proportion of radius to the cosine of the elevation, or in the proportion of the secant of elevation to the radius. It is evident, that this law of diminution of the strain is the same whether the strain arises from a load on any part of the rafter, or from...
Seite 28 - Who knows exactly, and who shall in this world declare, whence and why this creation took place ? The gods are subsequent to the production of this world: then who can know whence it proceeded ? or whence this varied world arose ? or whether it uphold [itself], or not ? He who, in the highest heaven, is the ruler of this universe, does indeed know; but not another can possess that knowledge.
Seite 502 - ¡mother, and so contrary to the ideas which had been formed respecting the figure of the terrestrial globe, would seem to indicate great irregularity ; and as there can be little doubt of the accuracy of...
Seite 278 - A lightning rod protects a conic space whose height is the length of the rod, whose base is a circle having its radius equal to the height of the rod, and whose side is the quadrant of a circle whose radius is equal to the height of the rod.
Seite 96 - A solar day is the interval between two successive returns of the sun to the same meridian. The sun moves through 360 degrees of longitude in one tropical year, or 365 days, 5 hours, 48 minutes, and 47 sec« onds. Hence the sun's mean daily motion in longitude is found by the proportion One year : one" day : : 360° : 59
Seite 256 - Previous to his time, the doctrine was held, that the earth is at rest in the centre of the universe, and that the sun, moon, and stars...
Seite 96 - ... so far as we know, be independent of every other ; for it is only in virtue of each being supposed to be an ultimate property or to point to an ultimate property that it has any claim to be taken into the account. Thus, if any two of the properties are found to be joint effects of the same cause or to stand to each other in the relation of cause and effect, they furnish only one argument instead of two.
Seite 215 - This value is greater than the truth by 6™ 13" only; since, according to La Place, the length of the tropical year at that time must have been equal to 365-242215 days, or about 4-2° shorter than in the present age. By such a result much was gained, but Hipparchus, conscious of the uncertainty attending the observations of the solstices, from the smallness of the variations in the lengths of the shadows cast by the gnomon, employed the method of the equinoxes, by observations made with the equatorial...
Seite 29 - ... cum sol igneus sit Océanique alatur umoribus, quia nullus ignis sine pastu aliquo possit permanere, necesse est aut ei similis sit igni, quem adhibemus ad usum atque victum, 41 aut ei, qui corporibus animantium continetur...