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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Page 48
... altitude of any object ( which may be found by the quadrant , ) is its greatest altitude for that day ; and when the sun is on the meridian , it is precisely 12 o'clock by the dial . The sun's meridian altitude is its hoon - day ...
... altitude of any object ( which may be found by the quadrant , ) is its greatest altitude for that day ; and when the sun is on the meridian , it is precisely 12 o'clock by the dial . The sun's meridian altitude is its hoon - day ...
Page 49
... altitude of the sun or a star on the meridian , and either of those objects be in the equinoctial , that altitude subtracted from 90 degrees will show the latitude of the place ; but if the sun be not in the equinoc- tial , it will be ...
... altitude of the sun or a star on the meridian , and either of those objects be in the equinoctial , that altitude subtracted from 90 degrees will show the latitude of the place ; but if the sun be not in the equinoc- tial , it will be ...
Page 50
... altitude is performed in the same manner as the deter- mination of our latitude ; for if an observer turn his back to the pole , and look towards the equator , he concludes that he is in a north- ern latitude , if the celestial bodies ...
... altitude is performed in the same manner as the deter- mination of our latitude ; for if an observer turn his back to the pole , and look towards the equator , he concludes that he is in a north- ern latitude , if the celestial bodies ...
Page 97
... , contrived an nstrument for ascertaining its quantity at ifferent altitudes , but this phenomenon baf ed all his endeavours . He attributed his ill VOL . I. 8 success to the gross vapours which float in the atmosphere ASTRONOMY . 97.
... , contrived an nstrument for ascertaining its quantity at ifferent altitudes , but this phenomenon baf ed all his endeavours . He attributed his ill VOL . I. 8 success to the gross vapours which float in the atmosphere ASTRONOMY . 97.
Page 98
... altitude , and proved that they diminish from the hori- zon to the zenith . As the state of the atmosphere is extremely variable , and the quantity of refraction is not always the same at the same altitude , no rule can be laid down for ...
... altitude , and proved that they diminish from the hori- zon to the zenith . As the state of the atmosphere is extremely variable , and the quantity of refraction is not always the same at the same altitude , no rule can be laid down for ...
Common terms and phrases
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
Popular passages
Page 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.
Page 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.
Page 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...
Page 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...
Page 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...
Page 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.
Page 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.