An Historical Account of the Origin and Progress of Astronomy: With Plates Illustrating, Chiefly, the Ancient SystemsBaldwin and Cradock, 1833 - 520 Seiten |
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Seite xi
... longitude and latitude , is rendered still further variable ; besides these , the tables contain the variable distances of the earth and planets from the sun , the movements of the apsides and nodes of their orbits , and all the ...
... longitude and latitude , is rendered still further variable ; besides these , the tables contain the variable distances of the earth and planets from the sun , the movements of the apsides and nodes of their orbits , and all the ...
Seite 10
... longitude and - latitude of Arcturus be obtained from astronomical formula for the year 900 B. C. , it will be found , by computation , that the heliacal rising of this star took place about eighteen days before the autumnal equinox ...
... longitude and - latitude of Arcturus be obtained from astronomical formula for the year 900 B. C. , it will be found , by computation , that the heliacal rising of this star took place about eighteen days before the autumnal equinox ...
Seite 82
... longitude passing through the star Regulus , probably because , when they chose the summer solstice for the commencement of one division of their agricultural year , that star was nearly in conjunction with the sun . If we suppose the ...
... longitude passing through the star Regulus , probably because , when they chose the summer solstice for the commencement of one division of their agricultural year , that star was nearly in conjunction with the sun . If we suppose the ...
Seite 83
... longitude 10 or 15 degrees , respectively , from the sun when it first , in Egypt , becomes disengaged from the rays of that luminary before his rising . At the former of these epochs , the longitude of Regulus was 86 degrees , and at ...
... longitude 10 or 15 degrees , respectively , from the sun when it first , in Egypt , becomes disengaged from the rays of that luminary before his rising . At the former of these epochs , the longitude of Regulus was 86 degrees , and at ...
Seite 85
... longitude by one of those degrees : after a more correct length of the year had been ascertained , a perception of the advantages of that division , arising from the many simple divisors contained in the number 360 ( which rendered it ...
... longitude by one of those degrees : after a more correct length of the year had been ascertained , a perception of the advantages of that division , arising from the many simple divisors contained in the number 360 ( which rendered it ...
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according Almagest ancient angle apogeum appear apsides Arabians ascertained ascribed assigned astronomer attraction axis Bailly cause celestial bodies centre Chaldeans Christ circle circumference coincide comets commencement computed consequently considered constellation Copernicus degrees described determined diameter direction earth eccentric ecliptic Egypt Egyptians elements epicycle epoch equal equator equinoctial points equinox Eudoxus evident fixed stars formed former gnomon Greeks heavens heliacal heliacal rising Hindus Hipparchus horizon hypothesis inequalities inferior planets instruments interval Jupiter Kepler known latitude latter length longitude luminary lunar mean distance mean motion mentioned Mercury meridian moon's movements nearly Newton nodes obliquity observations obtained opinion orbit parallax period phenomena philosopher planetary planets Plutarch pole precession probably Ptolemy respect retrograde revolution revolve right ascension rising Saturn shew shewn sidereal solar solstice sphere sun and moon sun's superior planets supposed surface theory tion Tycho Brahe variations velocity Venus vernal equinox zodiac
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Seite 387 - 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 32 - 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 510 - ¡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 286 - 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 100 - 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 262 - 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 98 - ... 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 221 - 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 33 - ... 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...
Seite 415 - ... repugnat enim, ut putemus id quod cogitat, eo ipso tempore quo cogitat, non existere. Ac proinde haec cognitio, ego cogito, ergo sum, est omnium prima et certissima, quae cuilibet ordine philosophanti occurrat.