Outlines of AstronomyLea & Blanchard, 1849 - 620 pages |
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Page 11
... sidereal to the solar day affected by precession . Incommensurability of the day and year . Its incon- venience . How obviated . The Julian Calendar . Irregularities at its first introduction . Reformed by Augustus . Gregorian ...
... sidereal to the solar day affected by precession . Incommensurability of the day and year . Its incon- venience . How obviated . The Julian Calendar . Irregularities at its first introduction . Reformed by Augustus . Gregorian ...
Page 73
... sidereal day , and is divided into 24 sidereal hours , and these again into minutes and seconds . A clock which marks sidereal time , i . e . which goes at such a rate as always to show Oh . Om . Os . when the equinox comes on the ...
... sidereal day , and is divided into 24 sidereal hours , and these again into minutes and seconds . A clock which marks sidereal time , i . e . which goes at such a rate as always to show Oh . Om . Os . when the equinox comes on the ...
Page 93
... days , a sidereal and a solar ; and if , instead of the sun , we observe the moon , we find a third , much longer than either , a lunar day , whose average duration is 24h 54m of our ordinary time , which last is solar time , being of ...
... days , a sidereal and a solar ; and if , instead of the sun , we observe the moon , we find a third , much longer than either , a lunar day , whose average duration is 24h 54m of our ordinary time , which last is solar time , being of ...
Page 95
... sidereal days , as it pervades every part of astronomy , requires to be early introduced , and never lost sight of . It is , as already observed , the mean or average length of the solar day , which is used in the civil reckoning of ...
... sidereal days , as it pervades every part of astronomy , requires to be early introduced , and never lost sight of . It is , as already observed , the mean or average length of the solar day , which is used in the civil reckoning of ...
Page 157
... sidereal time , at any other , B , it will be just so much sidereal time in error as the difference of longitudes of ... day in his reckoning of time . He will enter the day of his arrival in his diary , as Monday , for instance , when ...
... sidereal time , at any other , B , it will be just so much sidereal time in error as the difference of longitudes of ... day in his reckoning of time . He will enter the day of his arrival in his diary , as Monday , for instance , when ...
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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 greater heavens heliocentric horizon inclination increase inequality instance instrument interval Jupiter latitude latter less light longitude lunar magnitude mass mean measure meridian micrometrical moon moon's motion nearly nebula node normal force nutation object observed orbit parallax parallel perigee perihelion period perturbations planet planetary pole portion position precession proper motions proportion recede recess reckoned refraction remarkable rendered respect result revolution right ascension rotation round satellites Saturn seen sidereal sidereal day situation solar sphere spherical stars station sun's suppose surface syzygies tangential force telescope tion Uranus variation velocity visible volume whole zenith
Popular passages
Page 231 - 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 70 - 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 543 - This earth ? reciprocal, if land be there, Fields and inhabitants. Her spots thou seest As clouds, and clouds may rain, and rain produce Fruits in her soften'd soil, for some to eat Allotted there ; and other suns, perhaps, With their attendant moons, thou wilt descry, Communicating male and female light, Which two great sexes animate the world, Stored in each orb, perhaps, with some that live...
Page 286 - When we contemplate the constituents of the planetary system from the point of view which this relation affords us, it is no longer mere analogy which strikes us, no longer a general resemblance among them, as individuals independent of each other, and circulating about the sun, each according to its own peculiar nature, and connected with it by its own peculiar tie. The resemblance is now perceived to be a true family likeness ; they are bound up in one chain — interwoven in one web of mutual...
Page 18 - ... adverse to notions he may have previously formed for himself, or taken up, without examination, on the credit of others. Such an effort is, in fact, a commencement of that intellectual discipline which forms one of the most important ends of all science. It is the first movement of approach towards that state of mental purity which alone can fit us for a full and steady perception of moral beauty as well as physical adaptation. It is the 'euphrasy and rue' with which we must ' purge our sight...
Page 543 - In such instances, the larger star is usually of a ruddy or orange hue, while the smaller one appears blue or green, probably in virtue of that general law of optics, which provides that, when the retina is under the influence of excitement by any bright...
Page 589 - Every year whose number is not divisible by 4 without remainder, consists of 365 days ; every year which is so divisible, but is not divisible by 100, of 366 ; every year divisible by 100, but not by 400, again of 365 ; and every year divisible by 400, again of 366.
Page 86 - ... part of an inch ; a quantity requiring a powerful microscope to be discerned at all. Let any one figure to himself, therefore, the difficulty of placing on the circumference of a metallic circle of such dimensions (supposing the difficulty of its construction surmounted...
Page 350 - The projection of this ray ... to so enormous a length, "in a single day, conveys an impression of the intensity of "the forces acting to produce such a velocity of material "transfer through space, such as no other natural phenom"enon is capable of exciting. It is clear that if we have to deal "here with matter, such as we conceive it (viz. possessing "inertia), at all, it must be under the dominion of forces "incomparably more energetic than gravitation, and quite of "a different nature".