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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 ellipse epoch equal equator equinoctial equinox error exact excentricity fixed globe greater heavens heliocentric horizon inclination increase inequality instance instrument interval Jupiter latitude latter length 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
الصفحة 229 - 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.
الصفحة 541 - 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...
الصفحة 284 - 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...
الصفحة 16 - ... 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...
الصفحة 541 - 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...
الصفحة 587 - 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.
الصفحة 84 - ... 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...
الصفحة 348 - 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".