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 25
... complete rotation every twenty - four hours , and only half of it can be illuminated at a time ; it necessarily follows that any par ticular tract of country must sometimes be turned towards the sun and sometimes from it , and of course ...
... complete rotation every twenty - four hours , and only half of it can be illuminated at a time ; it necessarily follows that any par ticular tract of country must sometimes be turned towards the sun and sometimes from it , and of course ...
Page 39
... complete revolution before it can come into the same position with the sun that it had the preceding day . To illustrate this , we suppose both the hands of a watch or time- piece to set off together , at 1 o'clock , ASTRONOMY . 39.
... complete revolution before it can come into the same position with the sun that it had the preceding day . To illustrate this , we suppose both the hands of a watch or time- piece to set off together , at 1 o'clock , ASTRONOMY . 39.
Page 40
... complete circle before it can overtake the hour hand , or , in other words , before they will again exhibit the same rela tive position . Thus it is evident from observa- tion , that the sidereal days are shorter than the solar ones ...
... complete circle before it can overtake the hour hand , or , in other words , before they will again exhibit the same rela tive position . Thus it is evident from observa- tion , that the sidereal days are shorter than the solar ones ...
Page 42
... complete revolution , to bring the meridian of any place to the sun again ; and , by the same rule , the shortest day would be when the earth moved slowest in her orbit . These inequalities , together with those re sulting from the ...
... complete revolution , to bring the meridian of any place to the sun again ; and , by the same rule , the shortest day would be when the earth moved slowest in her orbit . These inequalities , together with those re sulting from the ...
Page 65
... completing one revolution in the course of a lunation , our globe would be constantly over the same meridian of the moon , if the motion of that satellite in her journey round the earth were also equable ; but she , like the other ...
... completing one revolution in the course of a lunation , our globe would be constantly over the same meridian of the moon , if the motion of that satellite in her journey round the earth were also equable ; but she , like the other ...
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.