Outlines of Astronomy |
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Page 32
... interval a Db , by measure- ment ; then it is clear that D , the visible horizon of both , will lie just half - way between them , and if we suppose a Db to be the sphere of the earth , and C its centre in the figure CD b B , we know Db ...
... interval a Db , by measure- ment ; then it is clear that D , the visible horizon of both , will lie just half - way between them , and if we suppose a Db to be the sphere of the earth , and C its centre in the figure CD b B , we know Db ...
Page 47
... intervals of time , ad infinitum . ( 55. ) Now , in this we have a lively picture of that grand phenomenon , the most ... interval of twenty - four hours is the first instance we encounter of that great law of periodicity , ' which , as ...
... intervals of time , ad infinitum . ( 55. ) Now , in this we have a lively picture of that grand phenomenon , the most ... interval of twenty - four hours is the first instance we encounter of that great law of periodicity , ' which , as ...
Page 49
... interval , as the night advances , he will not fail to perceive that they have changed their places , and advanced , as by a general movement , in a west- ward direction ; those towards the eastern quarter appearing to rise or recede ...
... interval , as the night advances , he will not fail to perceive that they have changed their places , and advanced , as by a general movement , in a west- ward direction ; those towards the eastern quarter appearing to rise or recede ...
Page 52
... interval . In this situation , no part of the heavens is concealed from his successive view . In a night of twelve hours ( supposing such a continuance of darkness possible at the equator ) the whole sphere will have passed in review ...
... interval . In this situation , no part of the heavens is concealed from his successive view . In a night of twelve hours ( supposing such a continuance of darkness possible at the equator ) the whole sphere will have passed in review ...
Page 56
... interval which separates the stars from the earth . If an observer walk round a circle not more than a few yards in diameter , and from different points in its circumference measure with a sextant or other more exact instrument adapted ...
... interval which separates the stars from the earth . If an observer walk round a circle not more than a few yards in diameter , and from different points in its circumference measure with a sextant or other more exact instrument adapted ...
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Common terms and phrases
altitude amount angle angular appear apsides ascertained astronomers axis bright calculation celestial centre circle comet curve described diameter difference direction disc distance disturbed body disturbing force diurnal diurnal motion double stars earth ecliptic effect elements ellipse epoch equal equator equinoctial equinox error exact excentricity fixed globe gravity greater heavens heliocentric horizon inclination increase inequality instance instrument interval Jupiter latitude latter length less light longitude lunar magnitude mass mean measure meridian moon moon's motion nearly nebula node normal force nutation object observed orbit parallax parallel perigee perihelion period perpendicular perturbations planet planetary pole portion position precession precisely proper motions proportion recede recess reckoned refraction remarkable respect result revolution right ascension rotation round satellites Saturn seen sidereal sidereal day situation solar sphere spherical stars station sun's suppose syzygies tangential force telescope tion Uranus variation velocity visible whole zenith
Popular passages
Page 211 - ... of those great deposits of dynamical efficiency which are laid up for human use in our coal strata. By them the waters of the sea are made to circulate in vapour through the air, and irrigate the land, producing springs and rivers.
Page 20 - Admission to its sanctuary, and to the privileges and feelings of a votary, is only to be gained by one means, sound and sufficient knowledge of mathematics, the great instrument of all exact inquiry, without which no man can ever make such advances in this or any other of the higher departments of science as can entitle him to form an independent opinion on any subject of discussion within their range.
Page 236 - that every particle of matter in the universe attracts every other particle, with a force whose direction is that of the line joining the two, and whose magnitude is directly as the product of their masses, and inversely as the square of their distances from each other.
Page 211 - The sun's rays are the ultimate source of almost every motion which takes place on the surface of the earth. By its heat are produced all winds, and those disturbances in the electric equilibrium of the atmosphere which give rise to the phenomena of lightning, and probably also to terrestrial action and the aurora.
Page 204 - The part of the sun's disc not occupied by spots is far from uniformly bright. Its ground is finely mottled with an appearance of minute, dark dots, or pores, which, when 'attentively watched, are found to be in a constant state of change. There is nothing which represents so faithfully this appearance as the slow subsidence of some flocculent chemical precipitates in a transparent fluid, when viewed perpendicularly from above...
Page 64 - Ocean, the first thing which strikes us is, that, the north-east and south-east monsoons, which are found the one on the north and the other on...
Page 281 - As to getting correct notions on this subject by drawing circles on paper, or, still worse, from those very childish toys called orreries, it is out of the question.
Page 514 - It is not easy for language to convey a full impression of the beauty and sublimity of the spectacle which this nebula offers, as it enters the field of view of a telescope fixed in Right Ascension, by the diurnal motion, ushered in as it is by so glorious and innumerable a procession of stars, to which it forms a sort of climax," and in a part of the heavens otherwise full of interest.
Page 281 - On such planets giants might exist, and those enormous animals which on earth require the buoyant power of water to counteract their weight, might there be denizens of the land.
Page 516 - ... inches of reflecting aperture, up to perfectly separated stars like the Milky Way, and clustering groups sufficiently insulated and condensed to come under the designation of irregular, and in some cases pretty rich clusters. But besides those, there are also nebulse in abundance, both regular and irregular ; globular clusters in every state of condensation ; and objects of a nebulous character quite peculiar, and which have no analogue in any other region of the heavens.