The Scientific Library; Or, Repository of Useful and Polite Literature: Comprising Astronomy, Geography, Mythology, Ancient History, Modern History, and Chronology ...S. Wood & Sons, 1818 |
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Página 22
... lunar eclipse which is not total , the obscure part is always bounded by a circular line , it is evident that the earth , which occasions that shadow , must be a spher- ical body . The most important objections ever brought against this ...
... lunar eclipse which is not total , the obscure part is always bounded by a circular line , it is evident that the earth , which occasions that shadow , must be a spher- ical body . The most important objections ever brought against this ...
Página 32
... lunar and the true solar year . Indeed , the defects of the ancient calendar were so obvious , that they afforded subject of ridicule in the Greek comedies , and induced several mathematicians to propose a reform to the Roman senate ...
... lunar and the true solar year . Indeed , the defects of the ancient calendar were so obvious , that they afforded subject of ridicule in the Greek comedies , and induced several mathematicians to propose a reform to the Roman senate ...
Página 34
... lunar months , which consist of about twenty - nine days and a half . That the odd six hours we have al- ready mentioned , might not be lost , an addi- tional day was introduced every fourth year , by reckoning the 24th of February ...
... lunar months , which consist of about twenty - nine days and a half . That the odd six hours we have al- ready mentioned , might not be lost , an addi- tional day was introduced every fourth year , by reckoning the 24th of February ...
Página 58
... practised , we shall close this chapter with a few remarks on the degree of accuracy which we may expect in the result of our lunar observations , or from our taking the distance either between the sun and moon , or 58 ASTRONOMY .
... practised , we shall close this chapter with a few remarks on the degree of accuracy which we may expect in the result of our lunar observations , or from our taking the distance either between the sun and moon , or 58 ASTRONOMY .
Página 59
... lunar distance within less than half a minute of the truth , and this joined to the above mentioned error , will occasion in the whole a mistake of three minutes in time , or three quarters of a degree of longitude . A greater degree of ...
... lunar distance within less than half a minute of the truth , and this joined to the above mentioned error , will occasion in the whole a mistake of three minutes in time , or three quarters of a degree of longitude . A greater degree of ...
Términos y frases comunes
aberration of light altitude annual revolution apparent motion appear Aries ascer ascertain astronomers called cause celestial centre circle comets computed consequently course darkness days and nights degree 15 degree 30 diameter discovered distance diurnal motion diurnal rotation divide Dominical letter earth earth's shadow east eastern side epact equa equal equator equinoctial equinox exactly extends from degree fixed stars full moon golden number gree half happen heavenly bodies heavens horizon isphere Julius Cæsar latitude less Libra light longitude luminary lunar lunar eclipses magni millions of miles minutes month moon's orbit nodes noon north or south north pole northern occasioned opposite parallel passes between degree phere planets Principal star quadrant Rectify the globe refraction satellites seasons second magnitude shadow falls situated solar eclipse south pole southern hemis southern hemisphere southern side sun and moon sun-dial sun's place supposed tides time-piece tion tude turn twelve western young readers
Pasajes populares
Página 13 - Amid the radiant orbs, That more than deck, that animate the sky, The life-infusing suns of other worlds ; Lo ! from the dread immensity of space Returning, with accelerated course, The rushing comet to the Sun descends ; And as he sinks below the shading earth, With awful train projected o'er the Heavens, The guilty nations tremble.
Página 100 - For I perceived that, if Light was propagated in Time, the apparent Place of a fixed Object would not be the same when ' the Eye is at Rest, as when it is moving in any other Direction, than that of the Line passing through the Eye and the Object ; and that, when the Eye is moving in different Directions, the apparent Place of the Object would be different.
Página 99 - March, 1726, the star was found to be 20" more southwardly than at the time of the first observation. It now, indeed, seemed to have arrived at its utmost limit southward, because, in several trials made about this time, no sensible difference was observed in its situation. By the middle of April it appeared to be returning back again towards the north ; and about the beginning of June it passed at the same distance from the zenith as it had done in December when it was first observed. From the quick...
Página 100 - For I perceived that, if light was propagated in time, the apparent place of a fixed object would not be the same when the eye is at rest, as when it is moving in any other direction than that of the line passing through the eye and...
Página 79 - Eclipses of the sun are more frequent than those of the moon, because his ecliptic limits are greater ; and yet we have more visible eclipses of the moon than of the sun, which is owing to their being seen from all parts of the earth where the moon is above the horizon when the eclipse happens ; whilst those of the sun can only be observed on that small portion of the hemisphere, on which the moon's shadow falls. The greatest number of eclipses, of both luminaries, which can happen in a year, is...
Página 99 - I then endeavoured to find out the cause of them. I was already convinced that the apparent motion of the stars was not owing to a nutation of the earth's axis. The next thing that offered itself was an alteration in the direction of the plumb-line, with which the instrument was constantly rectified; but this upon trial proved insufficient. Then I considered what refraction might do; but here also nothing satisfactory occurred.
Página 26 - ... if the earth's axis were perpendicular to the plane of its orbit, and the excessive variation which would result if the axis were nearly parallel to that plane.